Types#
MuJoCo defines a large number of types:
Two primitive types.
C enum types used to define categorical values. These can be classified as:
Enums used in mjModel.
Enums used in mjData.
Abstract visualization enums.
Enums used by the openGL renderer.
Enums used by the mjUI user interface package.
Note that the API does not use these enum types directly. Instead it uses ints, and the documentation/comments state that certain ints correspond to certain enum types. This is because we want the API to be compiler-independent, and the C standard does not dictate how many bytes must be used to represent an enum type. Nevertheless, for improved readiblity, we recommend using these types when calling API functions which take them as arguments.
C struct types. These can be classified as:
Main structs:
Auxillary struct types, also used by the engine.
Structs for collecting simulation statistics.
Structs for abstract visualization.
Structs used by the openGL renderer.
Structs used by the UI framework.
Structs used by engine plugins.
Several Function types for user-defined callbacks.
Notes regarding specific data structures that require detailed description.
Primitive types#
The two types below are defined in mjtnum.h.
mjtNum#
This is the floating-point type used throughout the simulator. If the symbol mjUSEDOUBLE is defined in
mjmodel.h, this type is defined as double, otherwise it is defined as float. Currently only the
double-precision version of MuJoCo is distributed, although the entire code base works with single-precision as well.
We may release the single-precision version in the future for efficiency reasons, but the double-precision version
will always be available. Thus it is safe to write user code assuming double precision. However, our preference is to
write code that works with either single or double precision. To this end we provide math utility functions that are
always defined with the correct floating-point type.
Note that changing mjUSEDOUBLE in mjtnum.h will not change how the library was compiled, and instead will
result in numerous link errors. In general, the header files distributed with precompiled MuJoCo should never be
changed by the user.
#ifdef mjUSEDOUBLE
typedef double mjtNum;
#else
typedef float mjtNum;
#endif
mjtByte#
Byte type used to represent boolean variables.
typedef unsigned char mjtByte;
Enum types#
Model#
The enums below are defined in mjmodel.h.
mjtDisableBit#
Constants which are powers of 2. They are used as bitmasks for the field disableflags of mjOption.
At runtime this field is m->opt.disableflags. The number of these constants is given by mjNDISABLE which is
also the length of the global string array mjDISABLESTRING with text descriptions of these flags.
typedef enum mjtDisableBit_ { // disable default feature bitflags
mjDSBL_CONSTRAINT = 1<<0, // entire constraint solver
mjDSBL_EQUALITY = 1<<1, // equality constraints
mjDSBL_FRICTIONLOSS = 1<<2, // joint and tendon frictionloss constraints
mjDSBL_LIMIT = 1<<3, // joint and tendon limit constraints
mjDSBL_CONTACT = 1<<4, // contact constraints
mjDSBL_PASSIVE = 1<<5, // passive forces
mjDSBL_GRAVITY = 1<<6, // gravitational forces
mjDSBL_CLAMPCTRL = 1<<7, // clamp control to specified range
mjDSBL_WARMSTART = 1<<8, // warmstart constraint solver
mjDSBL_FILTERPARENT = 1<<9, // remove collisions with parent body
mjDSBL_ACTUATION = 1<<10, // apply actuation forces
mjDSBL_REFSAFE = 1<<11, // integrator safety: make ref[0]>=2*timestep
mjDSBL_SENSOR = 1<<12, // sensors
mjDSBL_MIDPHASE = 1<<13, // mid-phase collision filtering
mjDSBL_EULERDAMP = 1<<14, // implicit integration of joint damping in Euler integrator
mjNDISABLE = 15 // number of disable flags
} mjtDisableBit;
mjtEnableBit#
Constants which are powers of 2. They are used as bitmasks for the field enableflags of mjOption.
At runtime this field is m->opt.enableflags. The number of these constants is given by mjNENABLE which is also
the length of the global string array mjENABLESTRING with text descriptions of these flags.
typedef enum mjtEnableBit_ { // enable optional feature bitflags
mjENBL_OVERRIDE = 1<<0, // override contact parameters
mjENBL_ENERGY = 1<<1, // energy computation
mjENBL_FWDINV = 1<<2, // record solver statistics
mjENBL_INVDISCRETE = 1<<3, // discrete-time inverse dynamics
// experimental features:
mjENBL_MULTICCD = 1<<4, // multi-point convex collision detection
mjENBL_ISLAND = 1<<5, // constraint island discovery
mjNENABLE = 6 // number of enable flags
} mjtEnableBit;
mjtJoint#
Primitive joint types. These values are used in m->jnt_type. The numbers in the comments indicate how many
positional coordinates each joint type has. Note that ball joints and rotational components of free joints are
represented as unit quaternions - which have 4 positional coordinates but 3 degrees of freedom each.
typedef enum mjtJoint_ { // type of degree of freedom
mjJNT_FREE = 0, // global position and orientation (quat) (7)
mjJNT_BALL, // orientation (quat) relative to parent (4)
mjJNT_SLIDE, // sliding distance along body-fixed axis (1)
mjJNT_HINGE // rotation angle (rad) around body-fixed axis (1)
} mjtJoint;
mjtGeom#
Geometric types supported by MuJoCo. The first group are “official” geom types that can be used in the model. The
second group are geom types that cannot be used in the model but are used by the visualizer to add decorative
elements. These values are used in m->geom_type and m->site_type.
typedef enum mjtGeom_ { // type of geometric shape
// regular geom types
mjGEOM_PLANE = 0, // plane
mjGEOM_HFIELD, // height field
mjGEOM_SPHERE, // sphere
mjGEOM_CAPSULE, // capsule
mjGEOM_ELLIPSOID, // ellipsoid
mjGEOM_CYLINDER, // cylinder
mjGEOM_BOX, // box
mjGEOM_MESH, // mesh
mjGEOM_SDF, // signed distance field
mjNGEOMTYPES, // number of regular geom types
// rendering-only geom types: not used in mjModel, not counted in mjNGEOMTYPES
mjGEOM_ARROW = 100, // arrow
mjGEOM_ARROW1, // arrow without wedges
mjGEOM_ARROW2, // arrow in both directions
mjGEOM_LINE, // line
mjGEOM_LINEBOX, // box with line edges
mjGEOM_FLEX, // flex
mjGEOM_SKIN, // skin
mjGEOM_LABEL, // text label
mjGEOM_TRIANGLE, // triangle
mjGEOM_NONE = 1001 // missing geom type
} mjtGeom;
mjtCamLight#
Dynamic modes for cameras and lights, specifying how the camera/light position and orientation are computed. These
values are used in m->cam_mode and m->light_mode.
typedef enum mjtCamLight_ { // tracking mode for camera and light
mjCAMLIGHT_FIXED = 0, // pos and rot fixed in body
mjCAMLIGHT_TRACK, // pos tracks body, rot fixed in global
mjCAMLIGHT_TRACKCOM, // pos tracks subtree com, rot fixed in body
mjCAMLIGHT_TARGETBODY, // pos fixed in body, rot tracks target body
mjCAMLIGHT_TARGETBODYCOM // pos fixed in body, rot tracks target subtree com
} mjtCamLight;
mjtTexture#
Texture types, specifying how the texture will be mapped. These values are used in m->tex_type.
typedef enum mjtTexture_ { // type of texture
mjTEXTURE_2D = 0, // 2d texture, suitable for planes and hfields
mjTEXTURE_CUBE, // cube texture, suitable for all other geom types
mjTEXTURE_SKYBOX // cube texture used as skybox
} mjtTexture;
mjtIntegrator#
Numerical integrator types. These values are used in m->opt.integrator.
typedef enum mjtIntegrator_ { // integrator mode
mjINT_EULER = 0, // semi-implicit Euler
mjINT_RK4, // 4th-order Runge Kutta
mjINT_IMPLICIT, // implicit in velocity
mjINT_IMPLICITFAST // implicit in velocity, no rne derivative
} mjtIntegrator;
mjtCone#
Available friction cone types. These values are used in m->opt.cone.
typedef enum mjtCone_ { // type of friction cone
mjCONE_PYRAMIDAL = 0, // pyramidal
mjCONE_ELLIPTIC // elliptic
} mjtCone;
mjtJacobian#
Available Jacobian types. These values are used in m->opt.jacobian.
typedef enum mjtJacobian_ { // type of constraint Jacobian
mjJAC_DENSE = 0, // dense
mjJAC_SPARSE, // sparse
mjJAC_AUTO // dense if nv<60, sparse otherwise
} mjtJacobian;
mjtSolver#
Available constraint solver algorithms. These values are used in m->opt.solver.
typedef enum mjtSolver_ { // constraint solver algorithm
mjSOL_PGS = 0, // PGS (dual)
mjSOL_CG, // CG (primal)
mjSOL_NEWTON // Newton (primal)
} mjtSolver;
mjtEq#
Equality constraint types. These values are used in m->eq_type.
typedef enum mjtEq_ { // type of equality constraint
mjEQ_CONNECT = 0, // connect two bodies at a point (ball joint)
mjEQ_WELD, // fix relative position and orientation of two bodies
mjEQ_JOINT, // couple the values of two scalar joints with cubic
mjEQ_TENDON, // couple the lengths of two tendons with cubic
mjEQ_FLEX, // fix all edge lengths of a flex
mjEQ_DISTANCE // unsupported, will cause an error if used
} mjtEq;
mjtWrap#
Tendon wrapping object types. These values are used in m->wrap_type.
typedef enum mjtWrap_ { // type of tendon wrap object
mjWRAP_NONE = 0, // null object
mjWRAP_JOINT, // constant moment arm
mjWRAP_PULLEY, // pulley used to split tendon
mjWRAP_SITE, // pass through site
mjWRAP_SPHERE, // wrap around sphere
mjWRAP_CYLINDER // wrap around (infinite) cylinder
} mjtWrap;
mjtTrn#
Actuator transmission types. These values are used in m->actuator_trntype.
typedef enum mjtTrn_ { // type of actuator transmission
mjTRN_JOINT = 0, // force on joint
mjTRN_JOINTINPARENT, // force on joint, expressed in parent frame
mjTRN_SLIDERCRANK, // force via slider-crank linkage
mjTRN_TENDON, // force on tendon
mjTRN_SITE, // force on site
mjTRN_BODY, // adhesion force on a body's geoms
mjTRN_UNDEFINED = 1000 // undefined transmission type
} mjtTrn;
mjtDyn#
Actuator dynamics types. These values are used in m->actuator_dyntype.
typedef enum mjtDyn_ { // type of actuator dynamics
mjDYN_NONE = 0, // no internal dynamics; ctrl specifies force
mjDYN_INTEGRATOR, // integrator: da/dt = u
mjDYN_FILTER, // linear filter: da/dt = (u-a) / tau
mjDYN_FILTEREXACT, // linear filter: da/dt = (u-a) / tau, with exact integration
mjDYN_MUSCLE, // piece-wise linear filter with two time constants
mjDYN_USER // user-defined dynamics type
} mjtDyn;
mjtGain#
Actuator gain types. These values are used in m->actuator_gaintype.
typedef enum mjtGain_ { // type of actuator gain
mjGAIN_FIXED = 0, // fixed gain
mjGAIN_AFFINE, // const + kp*length + kv*velocity
mjGAIN_MUSCLE, // muscle FLV curve computed by mju_muscleGain()
mjGAIN_USER // user-defined gain type
} mjtGain;
mjtBias#
Actuator bias types. These values are used in m->actuator_biastype.
typedef enum mjtBias_ { // type of actuator bias
mjBIAS_NONE = 0, // no bias
mjBIAS_AFFINE, // const + kp*length + kv*velocity
mjBIAS_MUSCLE, // muscle passive force computed by mju_muscleBias()
mjBIAS_USER // user-defined bias type
} mjtBias;
mjtObj#
MuJoCo object types. These are used, for example, in the support functions mj_name2id and mj_id2name to convert between object names and integer ids.
typedef enum mjtObj_ { // type of MujoCo object
mjOBJ_UNKNOWN = 0, // unknown object type
mjOBJ_BODY, // body
mjOBJ_XBODY, // body, used to access regular frame instead of i-frame
mjOBJ_JOINT, // joint
mjOBJ_DOF, // dof
mjOBJ_GEOM, // geom
mjOBJ_SITE, // site
mjOBJ_CAMERA, // camera
mjOBJ_LIGHT, // light
mjOBJ_FLEX, // flex
mjOBJ_MESH, // mesh
mjOBJ_SKIN, // skin
mjOBJ_HFIELD, // heightfield
mjOBJ_TEXTURE, // texture
mjOBJ_MATERIAL, // material for rendering
mjOBJ_PAIR, // geom pair to include
mjOBJ_EXCLUDE, // body pair to exclude
mjOBJ_EQUALITY, // equality constraint
mjOBJ_TENDON, // tendon
mjOBJ_ACTUATOR, // actuator
mjOBJ_SENSOR, // sensor
mjOBJ_NUMERIC, // numeric
mjOBJ_TEXT, // text
mjOBJ_TUPLE, // tuple
mjOBJ_KEY, // keyframe
mjOBJ_PLUGIN, // plugin instance
mjNOBJECT, // number of object types
// meta elements, do not appear in mjModel
mjOBJ_FRAME = 100 // frame
} mjtObj;
mjtConstraint#
Constraint types. These values are not used in mjModel, but are used in the mjData field d->efc_type when the list
of active constraints is constructed at each simulation time step.
typedef enum mjtConstraint_ { // type of constraint
mjCNSTR_EQUALITY = 0, // equality constraint
mjCNSTR_FRICTION_DOF, // dof friction
mjCNSTR_FRICTION_TENDON, // tendon friction
mjCNSTR_LIMIT_JOINT, // joint limit
mjCNSTR_LIMIT_TENDON, // tendon limit
mjCNSTR_CONTACT_FRICTIONLESS, // frictionless contact
mjCNSTR_CONTACT_PYRAMIDAL, // frictional contact, pyramidal friction cone
mjCNSTR_CONTACT_ELLIPTIC // frictional contact, elliptic friction cone
} mjtConstraint;
mjtConstraintState#
These values are used by the solver internally to keep track of the constraint states.
typedef enum mjtConstraintState_ { // constraint state
mjCNSTRSTATE_SATISFIED = 0, // constraint satisfied, zero cost (limit, contact)
mjCNSTRSTATE_QUADRATIC, // quadratic cost (equality, friction, limit, contact)
mjCNSTRSTATE_LINEARNEG, // linear cost, negative side (friction)
mjCNSTRSTATE_LINEARPOS, // linear cost, positive side (friction)
mjCNSTRSTATE_CONE // squared distance to cone cost (elliptic contact)
} mjtConstraintState;
mjtSensor#
Sensor types. These values are used in m->sensor_type.
typedef enum mjtSensor_ { // type of sensor
// common robotic sensors, attached to a site
mjSENS_TOUCH = 0, // scalar contact normal forces summed over sensor zone
mjSENS_ACCELEROMETER, // 3D linear acceleration, in local frame
mjSENS_VELOCIMETER, // 3D linear velocity, in local frame
mjSENS_GYRO, // 3D angular velocity, in local frame
mjSENS_FORCE, // 3D force between site's body and its parent body
mjSENS_TORQUE, // 3D torque between site's body and its parent body
mjSENS_MAGNETOMETER, // 3D magnetometer
mjSENS_RANGEFINDER, // scalar distance to nearest geom or site along z-axis
mjSENS_CAMPROJECTION, // pixel coordinates of a site in the camera image
// sensors related to scalar joints, tendons, actuators
mjSENS_JOINTPOS, // scalar joint position (hinge and slide only)
mjSENS_JOINTVEL, // scalar joint velocity (hinge and slide only)
mjSENS_TENDONPOS, // scalar tendon position
mjSENS_TENDONVEL, // scalar tendon velocity
mjSENS_ACTUATORPOS, // scalar actuator position
mjSENS_ACTUATORVEL, // scalar actuator velocity
mjSENS_ACTUATORFRC, // scalar actuator force
mjSENS_JOINTACTFRC, // scalar actuator force, measured at the joint
// sensors related to ball joints
mjSENS_BALLQUAT, // 4D ball joint quaternion
mjSENS_BALLANGVEL, // 3D ball joint angular velocity
// joint and tendon limit sensors, in constraint space
mjSENS_JOINTLIMITPOS, // joint limit distance-margin
mjSENS_JOINTLIMITVEL, // joint limit velocity
mjSENS_JOINTLIMITFRC, // joint limit force
mjSENS_TENDONLIMITPOS, // tendon limit distance-margin
mjSENS_TENDONLIMITVEL, // tendon limit velocity
mjSENS_TENDONLIMITFRC, // tendon limit force
// sensors attached to an object with spatial frame: (x)body, geom, site, camera
mjSENS_FRAMEPOS, // 3D position
mjSENS_FRAMEQUAT, // 4D unit quaternion orientation
mjSENS_FRAMEXAXIS, // 3D unit vector: x-axis of object's frame
mjSENS_FRAMEYAXIS, // 3D unit vector: y-axis of object's frame
mjSENS_FRAMEZAXIS, // 3D unit vector: z-axis of object's frame
mjSENS_FRAMELINVEL, // 3D linear velocity
mjSENS_FRAMEANGVEL, // 3D angular velocity
mjSENS_FRAMELINACC, // 3D linear acceleration
mjSENS_FRAMEANGACC, // 3D angular acceleration
// sensors related to kinematic subtrees; attached to a body (which is the subtree root)
mjSENS_SUBTREECOM, // 3D center of mass of subtree
mjSENS_SUBTREELINVEL, // 3D linear velocity of subtree
mjSENS_SUBTREEANGMOM, // 3D angular momentum of subtree
// global sensors
mjSENS_CLOCK, // simulation time
// plugin-controlled sensors
mjSENS_PLUGIN, // plugin-controlled
// user-defined sensor
mjSENS_USER // sensor data provided by mjcb_sensor callback
} mjtSensor;
mjtStage#
These are the compute stages for the skipstage parameters of mj_forwardSkip and mj_inverseSkip.
typedef enum mjtStage_ { // computation stage
mjSTAGE_NONE = 0, // no computations
mjSTAGE_POS, // position-dependent computations
mjSTAGE_VEL, // velocity-dependent computations
mjSTAGE_ACC // acceleration/force-dependent computations
} mjtStage;
mjtDataType#
These are the possible sensor data types, used in mjData.sensor_datatype.
typedef enum mjtDataType_ { // data type for sensors
mjDATATYPE_REAL = 0, // real values, no constraints
mjDATATYPE_POSITIVE, // positive values; 0 or negative: inactive
mjDATATYPE_AXIS, // 3D unit vector
mjDATATYPE_QUATERNION // unit quaternion
} mjtDataType;
Data#
The enums below are defined in mjdata.h.
mjtState#
State component elements as integer bitflags and several convenient combinations of these flags. Used by mj_getState, mj_setState and mj_stateSize.
typedef enum mjtState_ { // state elements
mjSTATE_TIME = 1<<0, // time
mjSTATE_QPOS = 1<<1, // position
mjSTATE_QVEL = 1<<2, // velocity
mjSTATE_ACT = 1<<3, // actuator activation
mjSTATE_WARMSTART = 1<<4, // acceleration used for warmstart
mjSTATE_CTRL = 1<<5, // control
mjSTATE_QFRC_APPLIED = 1<<6, // applied generalized force
mjSTATE_XFRC_APPLIED = 1<<7, // applied Cartesian force/torque
mjSTATE_EQ_ACTIVE = 1<<8, // enable/disable constraints
mjSTATE_MOCAP_POS = 1<<9, // positions of mocap bodies
mjSTATE_MOCAP_QUAT = 1<<10, // orientations of mocap bodies
mjSTATE_USERDATA = 1<<11, // user data
mjSTATE_PLUGIN = 1<<12, // plugin state
mjNSTATE = 13, // number of state elements
// convenience values for commonly used state specifications
mjSTATE_PHYSICS = mjSTATE_QPOS | mjSTATE_QVEL | mjSTATE_ACT,
mjSTATE_FULLPHYSICS = mjSTATE_PHYSICS | mjSTATE_TIME | mjSTATE_PLUGIN,
mjSTATE_USER = mjSTATE_CTRL | mjSTATE_QFRC_APPLIED | mjSTATE_XFRC_APPLIED |
mjSTATE_EQ_ACTIVE | mjSTATE_MOCAP_POS | mjSTATE_MOCAP_QUAT |
mjSTATE_USERDATA,
mjSTATE_INTEGRATION = mjSTATE_FULLPHYSICS | mjSTATE_USER | mjSTATE_WARMSTART
} mjtState;
mjtWarning#
Warning types. The number of warning types is given by mjNWARNING which is also the length of the array
mjData.warning.
typedef enum mjtWarning_ { // warning types
mjWARN_INERTIA = 0, // (near) singular inertia matrix
mjWARN_CONTACTFULL, // too many contacts in contact list
mjWARN_CNSTRFULL, // too many constraints
mjWARN_VGEOMFULL, // too many visual geoms
mjWARN_BADQPOS, // bad number in qpos
mjWARN_BADQVEL, // bad number in qvel
mjWARN_BADQACC, // bad number in qacc
mjWARN_BADCTRL, // bad number in ctrl
mjNWARNING // number of warnings
} mjtWarning;
mjtTimer#
Timer types. The number of timer types is given by mjNTIMER which is also the length of the array
mjData.timer, as well as the length of the string array mjTIMERSTRING with timer names.
typedef enum mjtTimer_ { // internal timers
// main api
mjTIMER_STEP = 0, // step
mjTIMER_FORWARD, // forward
mjTIMER_INVERSE, // inverse
// breakdown of step/forward
mjTIMER_POSITION, // fwdPosition
mjTIMER_VELOCITY, // fwdVelocity
mjTIMER_ACTUATION, // fwdActuation
mjTIMER_CONSTRAINT, // fwdConstraint
mjTIMER_ADVANCE, // mj_Euler, mj_implicit
// breakdown of fwdPosition
mjTIMER_POS_KINEMATICS, // kinematics, com, tendon, transmission
mjTIMER_POS_INERTIA, // inertia computations
mjTIMER_POS_COLLISION, // collision detection
mjTIMER_POS_MAKE, // make constraints
mjTIMER_POS_PROJECT, // project constraints
// breakdown of mj_collision
mjTIMER_COL_BROAD, // broadphase
mjTIMER_COL_NARROW, // narrowphase
mjNTIMER // number of timers
} mjtTimer;
Visualization#
The enums below are defined in mjvisualize.h.
mjtCatBit#
These are the available categories of geoms in the abstract visualizer. The bitmask can be used in the function mjr_render to specify which categories should be rendered.
typedef enum mjtCatBit_ { // bitflags for mjvGeom category
mjCAT_STATIC = 1, // model elements in body 0
mjCAT_DYNAMIC = 2, // model elements in all other bodies
mjCAT_DECOR = 4, // decorative geoms
mjCAT_ALL = 7 // select all categories
} mjtCatBit;
mjtMouse#
These are the mouse actions that the abstract visualizer recognizes. It is up to the user to intercept mouse events and translate them into these actions, as illustrated in simulate.cc.
typedef enum mjtMouse_ { // mouse interaction mode
mjMOUSE_NONE = 0, // no action
mjMOUSE_ROTATE_V, // rotate, vertical plane
mjMOUSE_ROTATE_H, // rotate, horizontal plane
mjMOUSE_MOVE_V, // move, vertical plane
mjMOUSE_MOVE_H, // move, horizontal plane
mjMOUSE_ZOOM, // zoom
mjMOUSE_SELECT // selection
} mjtMouse;
mjtPertBit#
These bitmasks enable the translational and rotational components of the mouse perturbation. For the regular mouse,
only one can be enabled at a time. For the 3D mouse (SpaceNavigator) both can be enabled simultaneously. They are used
in mjvPerturb.active.
typedef enum mjtPertBit_ { // mouse perturbations
mjPERT_TRANSLATE = 1, // translation
mjPERT_ROTATE = 2 // rotation
} mjtPertBit;
mjtCamera#
These are the possible camera types, used in mjvCamera.type.
typedef enum mjtCamera_ { // abstract camera type
mjCAMERA_FREE = 0, // free camera
mjCAMERA_TRACKING, // tracking camera; uses trackbodyid
mjCAMERA_FIXED, // fixed camera; uses fixedcamid
mjCAMERA_USER // user is responsible for setting OpenGL camera
} mjtCamera;
mjtLabel#
These are the abstract visualization elements that can have text labels. Used in mjvOption.label.
typedef enum mjtLabel_ { // object labeling
mjLABEL_NONE = 0, // nothing
mjLABEL_BODY, // body labels
mjLABEL_JOINT, // joint labels
mjLABEL_GEOM, // geom labels
mjLABEL_SITE, // site labels
mjLABEL_CAMERA, // camera labels
mjLABEL_LIGHT, // light labels
mjLABEL_TENDON, // tendon labels
mjLABEL_ACTUATOR, // actuator labels
mjLABEL_CONSTRAINT, // constraint labels
mjLABEL_FLEX, // flex labels
mjLABEL_SKIN, // skin labels
mjLABEL_SELECTION, // selected object
mjLABEL_SELPNT, // coordinates of selection point
mjLABEL_CONTACTPOINT, // contact information
mjLABEL_CONTACTFORCE, // magnitude of contact force
mjLABEL_ISLAND, // id of island
mjNLABEL // number of label types
} mjtLabel;
mjtFrame#
These are the MuJoCo objects whose spatial frames can be rendered. Used in mjvOption.frame.
typedef enum mjtFrame_ { // frame visualization
mjFRAME_NONE = 0, // no frames
mjFRAME_BODY, // body frames
mjFRAME_GEOM, // geom frames
mjFRAME_SITE, // site frames
mjFRAME_CAMERA, // camera frames
mjFRAME_LIGHT, // light frames
mjFRAME_CONTACT, // contact frames
mjFRAME_WORLD, // world frame
mjNFRAME // number of visualization frames
} mjtFrame;
mjtVisFlag#
These are indices in the array mjvOption.flags, whose elements enable/disable the visualization of the
corresponding model or decoration element.
typedef enum mjtVisFlag_ { // flags enabling model element visualization
mjVIS_CONVEXHULL = 0, // mesh convex hull
mjVIS_TEXTURE, // textures
mjVIS_JOINT, // joints
mjVIS_CAMERA, // cameras
mjVIS_ACTUATOR, // actuators
mjVIS_ACTIVATION, // activations
mjVIS_LIGHT, // lights
mjVIS_TENDON, // tendons
mjVIS_RANGEFINDER, // rangefinder sensors
mjVIS_CONSTRAINT, // point constraints
mjVIS_INERTIA, // equivalent inertia boxes
mjVIS_SCLINERTIA, // scale equivalent inertia boxes with mass
mjVIS_PERTFORCE, // perturbation force
mjVIS_PERTOBJ, // perturbation object
mjVIS_CONTACTPOINT, // contact points
mjVIS_ISLAND, // constraint islands
mjVIS_CONTACTFORCE, // contact force
mjVIS_CONTACTSPLIT, // split contact force into normal and tangent
mjVIS_TRANSPARENT, // make dynamic geoms more transparent
mjVIS_AUTOCONNECT, // auto connect joints and body coms
mjVIS_COM, // center of mass
mjVIS_SELECT, // selection point
mjVIS_STATIC, // static bodies
mjVIS_SKIN, // skin
mjVIS_FLEXVERT, // flex vertices
mjVIS_FLEXEDGE, // flex edges
mjVIS_FLEXFACE, // flex element faces
mjVIS_FLEXSKIN, // flex smooth skin (disables the rest)
mjVIS_BODYBVH, // body bounding volume hierarchy
mjVIS_FLEXBVH, // flex bounding volume hierarchy
mjVIS_MESHBVH, // mesh bounding volume hierarchy
mjVIS_SDFITER, // iterations of SDF gradient descent
mjNVISFLAG // number of visualization flags
} mjtVisFlag;
mjtRndFlag#
These are indices in the array mjvScene.flags, whose elements enable/disable OpenGL rendering effects.
typedef enum mjtRndFlag_ { // flags enabling rendering effects
mjRND_SHADOW = 0, // shadows
mjRND_WIREFRAME, // wireframe
mjRND_REFLECTION, // reflections
mjRND_ADDITIVE, // additive transparency
mjRND_SKYBOX, // skybox
mjRND_FOG, // fog
mjRND_HAZE, // haze
mjRND_SEGMENT, // segmentation with random color
mjRND_IDCOLOR, // segmentation with segid+1 color
mjRND_CULL_FACE, // cull backward faces
mjNRNDFLAG // number of rendering flags
} mjtRndFlag;
mjtStereo#
These are the possible stereo rendering types. They are used in mjvScene.stereo.
typedef enum mjtStereo_ { // type of stereo rendering
mjSTEREO_NONE = 0, // no stereo; use left eye only
mjSTEREO_QUADBUFFERED, // quad buffered; revert to side-by-side if no hardware support
mjSTEREO_SIDEBYSIDE // side-by-side
} mjtStereo;
Rendering#
The enums below are defined in mjrender.h.
mjtGridPos#
These are the possible grid positions for text overlays. They are used as an argument to the function mjr_overlay.
typedef enum mjtGridPos_ { // grid position for overlay
mjGRID_TOPLEFT = 0, // top left
mjGRID_TOPRIGHT, // top right
mjGRID_BOTTOMLEFT, // bottom left
mjGRID_BOTTOMRIGHT, // bottom right
mjGRID_TOP, // top center
mjGRID_BOTTOM, // bottom center
mjGRID_LEFT, // left center
mjGRID_RIGHT // right center
} mjtGridPos;
mjtFramebuffer#
These are the possible framebuffers. They are used as an argument to the function mjr_setBuffer.
typedef enum mjtFramebuffer_ { // OpenGL framebuffer option
mjFB_WINDOW = 0, // default/window buffer
mjFB_OFFSCREEN // offscreen buffer
} mjtFramebuffer;
mjtDepthMap#
These are the depth mapping options. They are used as a value for the readPixelDepth attribute of the
mjrContext struct, to control how the depth returned by mjr_readPixels is mapped from
znear to zfar.
typedef enum mjtDepthMap_ { // depth mapping for `mjr_readPixels`
mjDEPTH_ZERONEAR = 0, // standard depth map; 0: znear, 1: zfar
mjDEPTH_ZEROFAR = 1 // reversed depth map; 1: znear, 0: zfar
} mjtDepthMap;
mjtFontScale#
These are the possible font sizes. The fonts are predefined bitmaps stored in the dynamic library at three different sizes.
typedef enum mjtFontScale_ { // font scale, used at context creation
mjFONTSCALE_50 = 50, // 50% scale, suitable for low-res rendering
mjFONTSCALE_100 = 100, // normal scale, suitable in the absence of DPI scaling
mjFONTSCALE_150 = 150, // 150% scale
mjFONTSCALE_200 = 200, // 200% scale
mjFONTSCALE_250 = 250, // 250% scale
mjFONTSCALE_300 = 300 // 300% scale
} mjtFontScale;
mjtFont#
These are the possible font types.
typedef enum mjtFont_ { // font type, used at each text operation
mjFONT_NORMAL = 0, // normal font
mjFONT_SHADOW, // normal font with shadow (for higher contrast)
mjFONT_BIG // big font (for user alerts)
} mjtFont;
User Interface#
The enums below are defined in mjui.h.
mjtEvent#
Event types used in the UI framework.
typedef enum mjtEvent_ { // mouse and keyboard event type
mjEVENT_NONE = 0, // no event
mjEVENT_MOVE, // mouse move
mjEVENT_PRESS, // mouse button press
mjEVENT_RELEASE, // mouse button release
mjEVENT_SCROLL, // scroll
mjEVENT_KEY, // key press
mjEVENT_RESIZE, // resize
mjEVENT_REDRAW, // redraw
mjEVENT_FILESDROP // files drop
} mjtEvent;
mjtItem#
Item types used in the UI framework.
typedef enum mjtItem_ { // UI item type
mjITEM_END = -2, // end of definition list (not an item)
mjITEM_SECTION = -1, // section (not an item)
mjITEM_SEPARATOR = 0, // separator
mjITEM_STATIC, // static text
mjITEM_BUTTON, // button
// the rest have data pointer
mjITEM_CHECKINT, // check box, int value
mjITEM_CHECKBYTE, // check box, mjtByte value
mjITEM_RADIO, // radio group
mjITEM_RADIOLINE, // radio group, single line
mjITEM_SELECT, // selection box
mjITEM_SLIDERINT, // slider, int value
mjITEM_SLIDERNUM, // slider, mjtNum value
mjITEM_EDITINT, // editable array, int values
mjITEM_EDITNUM, // editable array, mjtNum values
mjITEM_EDITFLOAT, // editable array, float values
mjITEM_EDITTXT, // editable text
mjNITEM // number of item types
} mjtItem;
Plugins#
The enums below are defined in mjplugin.h. See Engine plugins for details.
mjtPluginCapabilityBit#
Capabilities declared by an engine plugin.
typedef enum mjtPluginCapabilityBit_ {
mjPLUGIN_ACTUATOR = 1<<0, // actuator forces
mjPLUGIN_SENSOR = 1<<1, // sensor measurements
mjPLUGIN_PASSIVE = 1<<2, // passive forces
mjPLUGIN_SDF = 1<<3, // signed distance fields
} mjtPluginCapabilityBit;
Struct types#
The three central struct types for physics simulation are mjModel, mjOption (embedded in mjModel) and mjData. An introductory discussion of these strucures can be found in the Overview.
mjModel#
This is the main data structure holding the MuJoCo model. It is treated as constant by the simulator. Some specific details regarding datastructures in mjModel can be found below in Notes.
struct mjModel_ {
// ------------------------------- sizes
// sizes needed at mjModel construction
int nq; // number of generalized coordinates = dim(qpos)
int nv; // number of degrees of freedom = dim(qvel)
int nu; // number of actuators/controls = dim(ctrl)
int na; // number of activation states = dim(act)
int nbody; // number of bodies
int nbvh; // number of total bounding volumes in all bodies
int nbvhstatic; // number of static bounding volumes (aabb stored in mjModel)
int nbvhdynamic; // number of dynamic bounding volumes (aabb stored in mjData)
int njnt; // number of joints
int ngeom; // number of geoms
int nsite; // number of sites
int ncam; // number of cameras
int nlight; // number of lights
int nflex; // number of flexes
int nflexvert; // number of vertices in all flexes
int nflexedge; // number of edges in all flexes
int nflexelem; // number of elements in all flexes
int nflexelemdata; // number of element vertex ids in all flexes
int nflexshelldata; // number of shell fragment vertex ids in all flexes
int nflexevpair; // number of element-vertex pairs in all flexes
int nflextexcoord; // number of vertices with texture coordinates
int nmesh; // number of meshes
int nmeshvert; // number of vertices in all meshes
int nmeshnormal; // number of normals in all meshes
int nmeshtexcoord; // number of texcoords in all meshes
int nmeshface; // number of triangular faces in all meshes
int nmeshgraph; // number of ints in mesh auxiliary data
int nskin; // number of skins
int nskinvert; // number of vertices in all skins
int nskintexvert; // number of vertiex with texcoords in all skins
int nskinface; // number of triangular faces in all skins
int nskinbone; // number of bones in all skins
int nskinbonevert; // number of vertices in all skin bones
int nhfield; // number of heightfields
int nhfielddata; // number of data points in all heightfields
int ntex; // number of textures
int ntexdata; // number of bytes in texture rgb data
int nmat; // number of materials
int npair; // number of predefined geom pairs
int nexclude; // number of excluded geom pairs
int neq; // number of equality constraints
int ntendon; // number of tendons
int nwrap; // number of wrap objects in all tendon paths
int nsensor; // number of sensors
int nnumeric; // number of numeric custom fields
int nnumericdata; // number of mjtNums in all numeric fields
int ntext; // number of text custom fields
int ntextdata; // number of mjtBytes in all text fields
int ntuple; // number of tuple custom fields
int ntupledata; // number of objects in all tuple fields
int nkey; // number of keyframes
int nmocap; // number of mocap bodies
int nplugin; // number of plugin instances
int npluginattr; // number of chars in all plugin config attributes
int nuser_body; // number of mjtNums in body_user
int nuser_jnt; // number of mjtNums in jnt_user
int nuser_geom; // number of mjtNums in geom_user
int nuser_site; // number of mjtNums in site_user
int nuser_cam; // number of mjtNums in cam_user
int nuser_tendon; // number of mjtNums in tendon_user
int nuser_actuator; // number of mjtNums in actuator_user
int nuser_sensor; // number of mjtNums in sensor_user
int nnames; // number of chars in all names
int nnames_map; // number of slots in the names hash map
int npaths; // number of chars in all paths
// sizes set after mjModel construction (only affect mjData)
int nM; // number of non-zeros in sparse inertia matrix
int nD; // number of non-zeros in sparse dof-dof matrix
int nB; // number of non-zeros in sparse body-dof matrix
int ntree; // number of kinematic trees under world body
int ngravcomp; // number of bodies with nonzero gravcomp
int nemax; // number of potential equality-constraint rows
int njmax; // number of available rows in constraint Jacobian
int nconmax; // number of potential contacts in contact list
int nuserdata; // number of mjtNums reserved for the user
int nsensordata; // number of mjtNums in sensor data vector
int npluginstate; // number of mjtNums in plugin state vector
size_t narena; // number of bytes in the mjData arena (inclusive of stack)
size_t nbuffer; // number of bytes in buffer
// ------------------------------- options and statistics
mjOption opt; // physics options
mjVisual vis; // visualization options
mjStatistic stat; // model statistics
// ------------------------------- buffers
// main buffer
void* buffer; // main buffer; all pointers point in it (nbuffer)
// default generalized coordinates
mjtNum* qpos0; // qpos values at default pose (nq x 1)
mjtNum* qpos_spring; // reference pose for springs (nq x 1)
// bodies
int* body_parentid; // id of body's parent (nbody x 1)
int* body_rootid; // id of root above body (nbody x 1)
int* body_weldid; // id of body that this body is welded to (nbody x 1)
int* body_mocapid; // id of mocap data; -1: none (nbody x 1)
int* body_jntnum; // number of joints for this body (nbody x 1)
int* body_jntadr; // start addr of joints; -1: no joints (nbody x 1)
int* body_dofnum; // number of motion degrees of freedom (nbody x 1)
int* body_dofadr; // start addr of dofs; -1: no dofs (nbody x 1)
int* body_treeid; // id of body's kinematic tree; -1: static (nbody x 1)
int* body_geomnum; // number of geoms (nbody x 1)
int* body_geomadr; // start addr of geoms; -1: no geoms (nbody x 1)
mjtByte* body_simple; // 1: diag M; 2: diag M, sliders only (nbody x 1)
mjtByte* body_sameframe; // inertial frame is same as body frame (nbody x 1)
mjtNum* body_pos; // position offset rel. to parent body (nbody x 3)
mjtNum* body_quat; // orientation offset rel. to parent body (nbody x 4)
mjtNum* body_ipos; // local position of center of mass (nbody x 3)
mjtNum* body_iquat; // local orientation of inertia ellipsoid (nbody x 4)
mjtNum* body_mass; // mass (nbody x 1)
mjtNum* body_subtreemass; // mass of subtree starting at this body (nbody x 1)
mjtNum* body_inertia; // diagonal inertia in ipos/iquat frame (nbody x 3)
mjtNum* body_invweight0; // mean inv inert in qpos0 (trn, rot) (nbody x 2)
mjtNum* body_gravcomp; // antigravity force, units of body weight (nbody x 1)
mjtNum* body_margin; // MAX over all geom margins (nbody x 1)
mjtNum* body_user; // user data (nbody x nuser_body)
int* body_plugin; // plugin instance id; -1: not in use (nbody x 1)
int* body_contype; // OR over all geom contypes (nbody x 1)
int* body_conaffinity; // OR over all geom conaffinities (nbody x 1)
int* body_bvhadr; // address of bvh root (nbody x 1)
int* body_bvhnum; // number of bounding volumes (nbody x 1)
// bounding volume hierarchy
int* bvh_depth; // depth in the bounding volume hierarchy (nbvh x 1)
int* bvh_child; // left and right children in tree (nbvh x 2)
int* bvh_nodeid; // geom or elem id of node; -1: non-leaf (nbvh x 1)
mjtNum* bvh_aabb; // local bounding box (center, size) (nbvhstatic x 6)
// joints
int* jnt_type; // type of joint (mjtJoint) (njnt x 1)
int* jnt_qposadr; // start addr in 'qpos' for joint's data (njnt x 1)
int* jnt_dofadr; // start addr in 'qvel' for joint's data (njnt x 1)
int* jnt_bodyid; // id of joint's body (njnt x 1)
int* jnt_group; // group for visibility (njnt x 1)
mjtByte* jnt_limited; // does joint have limits (njnt x 1)
mjtByte* jnt_actfrclimited; // does joint have actuator force limits (njnt x 1)
mjtByte* jnt_actgravcomp; // is gravcomp force applied via actuators (njnt x 1)
mjtNum* jnt_solref; // constraint solver reference: limit (njnt x mjNREF)
mjtNum* jnt_solimp; // constraint solver impedance: limit (njnt x mjNIMP)
mjtNum* jnt_pos; // local anchor position (njnt x 3)
mjtNum* jnt_axis; // local joint axis (njnt x 3)
mjtNum* jnt_stiffness; // stiffness coefficient (njnt x 1)
mjtNum* jnt_range; // joint limits (njnt x 2)
mjtNum* jnt_actfrcrange; // range of total actuator force (njnt x 2)
mjtNum* jnt_margin; // min distance for limit detection (njnt x 1)
mjtNum* jnt_user; // user data (njnt x nuser_jnt)
// dofs
int* dof_bodyid; // id of dof's body (nv x 1)
int* dof_jntid; // id of dof's joint (nv x 1)
int* dof_parentid; // id of dof's parent; -1: none (nv x 1)
int* dof_treeid; // id of dof's kinematic tree (nv x 1)
int* dof_Madr; // dof address in M-diagonal (nv x 1)
int* dof_simplenum; // number of consecutive simple dofs (nv x 1)
mjtNum* dof_solref; // constraint solver reference:frictionloss (nv x mjNREF)
mjtNum* dof_solimp; // constraint solver impedance:frictionloss (nv x mjNIMP)
mjtNum* dof_frictionloss; // dof friction loss (nv x 1)
mjtNum* dof_armature; // dof armature inertia/mass (nv x 1)
mjtNum* dof_damping; // damping coefficient (nv x 1)
mjtNum* dof_invweight0; // diag. inverse inertia in qpos0 (nv x 1)
mjtNum* dof_M0; // diag. inertia in qpos0 (nv x 1)
// geoms
int* geom_type; // geometric type (mjtGeom) (ngeom x 1)
int* geom_contype; // geom contact type (ngeom x 1)
int* geom_conaffinity; // geom contact affinity (ngeom x 1)
int* geom_condim; // contact dimensionality (1, 3, 4, 6) (ngeom x 1)
int* geom_bodyid; // id of geom's body (ngeom x 1)
int* geom_dataid; // id of geom's mesh/hfield; -1: none (ngeom x 1)
int* geom_matid; // material id for rendering; -1: none (ngeom x 1)
int* geom_group; // group for visibility (ngeom x 1)
int* geom_priority; // geom contact priority (ngeom x 1)
int* geom_plugin; // plugin instance id; -1: not in use (ngeom x 1)
mjtByte* geom_sameframe; // same as body frame (1) or iframe (2) (ngeom x 1)
mjtNum* geom_solmix; // mixing coef for solref/imp in geom pair (ngeom x 1)
mjtNum* geom_solref; // constraint solver reference: contact (ngeom x mjNREF)
mjtNum* geom_solimp; // constraint solver impedance: contact (ngeom x mjNIMP)
mjtNum* geom_size; // geom-specific size parameters (ngeom x 3)
mjtNum* geom_aabb; // bounding box, (center, size) (ngeom x 6)
mjtNum* geom_rbound; // radius of bounding sphere (ngeom x 1)
mjtNum* geom_pos; // local position offset rel. to body (ngeom x 3)
mjtNum* geom_quat; // local orientation offset rel. to body (ngeom x 4)
mjtNum* geom_friction; // friction for (slide, spin, roll) (ngeom x 3)
mjtNum* geom_margin; // detect contact if dist<margin (ngeom x 1)
mjtNum* geom_gap; // include in solver if dist<margin-gap (ngeom x 1)
mjtNum* geom_fluid; // fluid interaction parameters (ngeom x mjNFLUID)
mjtNum* geom_user; // user data (ngeom x nuser_geom)
float* geom_rgba; // rgba when material is omitted (ngeom x 4)
// sites
int* site_type; // geom type for rendering (mjtGeom) (nsite x 1)
int* site_bodyid; // id of site's body (nsite x 1)
int* site_matid; // material id for rendering; -1: none (nsite x 1)
int* site_group; // group for visibility (nsite x 1)
mjtByte* site_sameframe; // same as body frame (1) or iframe (2) (nsite x 1)
mjtNum* site_size; // geom size for rendering (nsite x 3)
mjtNum* site_pos; // local position offset rel. to body (nsite x 3)
mjtNum* site_quat; // local orientation offset rel. to body (nsite x 4)
mjtNum* site_user; // user data (nsite x nuser_site)
float* site_rgba; // rgba when material is omitted (nsite x 4)
// cameras
int* cam_mode; // camera tracking mode (mjtCamLight) (ncam x 1)
int* cam_bodyid; // id of camera's body (ncam x 1)
int* cam_targetbodyid; // id of targeted body; -1: none (ncam x 1)
mjtNum* cam_pos; // position rel. to body frame (ncam x 3)
mjtNum* cam_quat; // orientation rel. to body frame (ncam x 4)
mjtNum* cam_poscom0; // global position rel. to sub-com in qpos0 (ncam x 3)
mjtNum* cam_pos0; // global position rel. to body in qpos0 (ncam x 3)
mjtNum* cam_mat0; // global orientation in qpos0 (ncam x 9)
int* cam_resolution; // [width, height] in pixels (ncam x 2)
mjtNum* cam_fovy; // y-field of view (deg) (ncam x 1)
float* cam_intrinsic; // [focal length; principal point] (ncam x 4)
float* cam_sensorsize; // sensor size (ncam x 2)
mjtNum* cam_ipd; // inter-pupilary distance (ncam x 1)
mjtNum* cam_user; // user data (ncam x nuser_cam)
// lights
int* light_mode; // light tracking mode (mjtCamLight) (nlight x 1)
int* light_bodyid; // id of light's body (nlight x 1)
int* light_targetbodyid; // id of targeted body; -1: none (nlight x 1)
mjtByte* light_directional; // directional light (nlight x 1)
mjtByte* light_castshadow; // does light cast shadows (nlight x 1)
float* light_bulbradius; // light radius for soft shadows (nlight x 1)
mjtByte* light_active; // is light on (nlight x 1)
mjtNum* light_pos; // position rel. to body frame (nlight x 3)
mjtNum* light_dir; // direction rel. to body frame (nlight x 3)
mjtNum* light_poscom0; // global position rel. to sub-com in qpos0 (nlight x 3)
mjtNum* light_pos0; // global position rel. to body in qpos0 (nlight x 3)
mjtNum* light_dir0; // global direction in qpos0 (nlight x 3)
float* light_attenuation; // OpenGL attenuation (quadratic model) (nlight x 3)
float* light_cutoff; // OpenGL cutoff (nlight x 1)
float* light_exponent; // OpenGL exponent (nlight x 1)
float* light_ambient; // ambient rgb (alpha=1) (nlight x 3)
float* light_diffuse; // diffuse rgb (alpha=1) (nlight x 3)
float* light_specular; // specular rgb (alpha=1) (nlight x 3)
// flexes: contact properties
int* flex_contype; // flex contact type (nflex x 1)
int* flex_conaffinity; // flex contact affinity (nflex x 1)
int* flex_condim; // contact dimensionality (1, 3, 4, 6) (nflex x 1)
int* flex_priority; // flex contact priority (nflex x 1)
mjtNum* flex_solmix; // mix coef for solref/imp in contact pair (nflex x 1)
mjtNum* flex_solref; // constraint solver reference: contact (nflex x mjNREF)
mjtNum* flex_solimp; // constraint solver impedance: contact (nflex x mjNIMP)
mjtNum* flex_friction; // friction for (slide, spin, roll) (nflex x 3)
mjtNum* flex_margin; // detect contact if dist<margin (nflex x 1)
mjtNum* flex_gap; // include in solver if dist<margin-gap (nflex x 1)
mjtByte* flex_internal; // internal flex collision enabled (nflex x 1)
int* flex_selfcollide; // self collision mode (mjtFlexSelf) (nflex x 1)
int* flex_activelayers; // number of active element layers, 3D only (nflex x 1)
// flexes: other properties
int* flex_dim; // 1: lines, 2: triangles, 3: tetrahedra (nflex x 1)
int* flex_matid; // material id for rendering (nflex x 1)
int* flex_group; // group for visibility (nflex x 1)
int* flex_vertadr; // first vertex address (nflex x 1)
int* flex_vertnum; // number of vertices (nflex x 1)
int* flex_edgeadr; // first edge address (nflex x 1)
int* flex_edgenum; // number of edges (nflex x 1)
int* flex_elemadr; // first element address (nflex x 1)
int* flex_elemnum; // number of elements (nflex x 1)
int* flex_elemdataadr; // first element vertex id address (nflex x 1)
int* flex_shellnum; // number of shells (nflex x 1)
int* flex_shelldataadr; // first shell data address (nflex x 1)
int* flex_evpairadr; // first evpair address (nflex x 1)
int* flex_evpairnum; // number of evpairs (nflex x 1)
int* flex_texcoordadr; // address in flex_texcoord; -1: none (nflex x 1)
int* flex_vertbodyid; // vertex body ids (nflexvert x 1)
int* flex_edge; // edge vertex ids (2 per edge) (nflexedge x 2)
int* flex_elem; // element vertex ids (dim+1 per elem) (nflexelemdata x 1)
int* flex_elemlayer; // element distance from surface, 3D only (nflexelem x 1)
int* flex_shell; // shell fragment vertex ids (dim per frag) (nflexshelldata x 1)
int* flex_evpair; // (element, vertex) collision pairs (nflexevpair x 2)
mjtNum* flex_vert; // vertex positions in local body frames (nflexvert x 3)
mjtNum* flex_xvert0; // Cartesian vertex positions in qpos0 (nflexvert x 3)
mjtNum* flexedge_length0; // edge lengths in qpos0 (nflexedge x 1)
mjtNum* flexedge_invweight0; // edge inv. weight in qpos0 (nflexedge x 1)
mjtNum* flex_radius; // radius around primitive element (nflex x 1)
mjtNum* flex_edgestiffness; // edge stiffness (nflex x 1)
mjtNum* flex_edgedamping; // edge damping (nflex x 1)
mjtByte* flex_edgeequality; // is edge equality constraint defined (nflex x 1)
mjtByte* flex_rigid; // are all verices in the same body (nflex x 1)
mjtByte* flexedge_rigid; // are both edge vertices in same body (nflexedge x 1)
mjtByte* flex_centered; // are all vertex coordinates (0,0,0) (nflex x 1)
mjtByte* flex_flatskin; // render flex skin with flat shading (nflex x 1)
int* flex_bvhadr; // address of bvh root; -1: no bvh (nflex x 1)
int* flex_bvhnum; // number of bounding volumes (nflex x 1)
float* flex_rgba; // rgba when material is omitted (nflex x 4)
float* flex_texcoord; // vertex texture coordinates (nflextexcoord x 2)
// meshes
int* mesh_vertadr; // first vertex address (nmesh x 1)
int* mesh_vertnum; // number of vertices (nmesh x 1)
int* mesh_faceadr; // first face address (nmesh x 1)
int* mesh_facenum; // number of faces (nmesh x 1)
int* mesh_bvhadr; // address of bvh root (nmesh x 1)
int* mesh_bvhnum; // number of bvh (nmesh x 1)
int* mesh_normaladr; // first normal address (nmesh x 1)
int* mesh_normalnum; // number of normals (nmesh x 1)
int* mesh_texcoordadr; // texcoord data address; -1: no texcoord (nmesh x 1)
int* mesh_texcoordnum; // number of texcoord (nmesh x 1)
int* mesh_graphadr; // graph data address; -1: no graph (nmesh x 1)
float* mesh_vert; // vertex positions for all meshes (nmeshvert x 3)
float* mesh_normal; // normals for all meshes (nmeshnormal x 3)
float* mesh_texcoord; // vertex texcoords for all meshes (nmeshtexcoord x 2)
int* mesh_face; // vertex face data (nmeshface x 3)
int* mesh_facenormal; // normal face data (nmeshface x 3)
int* mesh_facetexcoord; // texture face data (nmeshface x 3)
int* mesh_graph; // convex graph data (nmeshgraph x 1)
mjtNum* mesh_scale; // scaling applied to asset vertices (nmesh x 3)
mjtNum* mesh_pos; // translation applied to asset vertices (nmesh x 3)
mjtNum* mesh_quat; // rotation applied to asset vertices (nmesh x 4)
int* mesh_pathadr; // address of asset path for mesh; -1: none (nmesh x 1)
// skins
int* skin_matid; // skin material id; -1: none (nskin x 1)
int* skin_group; // group for visibility (nskin x 1)
float* skin_rgba; // skin rgba (nskin x 4)
float* skin_inflate; // inflate skin in normal direction (nskin x 1)
int* skin_vertadr; // first vertex address (nskin x 1)
int* skin_vertnum; // number of vertices (nskin x 1)
int* skin_texcoordadr; // texcoord data address; -1: no texcoord (nskin x 1)
int* skin_faceadr; // first face address (nskin x 1)
int* skin_facenum; // number of faces (nskin x 1)
int* skin_boneadr; // first bone in skin (nskin x 1)
int* skin_bonenum; // number of bones in skin (nskin x 1)
float* skin_vert; // vertex positions for all skin meshes (nskinvert x 3)
float* skin_texcoord; // vertex texcoords for all skin meshes (nskintexvert x 2)
int* skin_face; // triangle faces for all skin meshes (nskinface x 3)
int* skin_bonevertadr; // first vertex in each bone (nskinbone x 1)
int* skin_bonevertnum; // number of vertices in each bone (nskinbone x 1)
float* skin_bonebindpos; // bind pos of each bone (nskinbone x 3)
float* skin_bonebindquat; // bind quat of each bone (nskinbone x 4)
int* skin_bonebodyid; // body id of each bone (nskinbone x 1)
int* skin_bonevertid; // mesh ids of vertices in each bone (nskinbonevert x 1)
float* skin_bonevertweight; // weights of vertices in each bone (nskinbonevert x 1)
int* skin_pathadr; // address of asset path for skin; -1: none (nskin x 1)
// height fields
mjtNum* hfield_size; // (x, y, z_top, z_bottom) (nhfield x 4)
int* hfield_nrow; // number of rows in grid (nhfield x 1)
int* hfield_ncol; // number of columns in grid (nhfield x 1)
int* hfield_adr; // address in hfield_data (nhfield x 1)
float* hfield_data; // elevation data (nhfielddata x 1)
int* hfield_pathadr; // address of hfield asset path; -1: none (nhfield x 1)
// textures
int* tex_type; // texture type (mjtTexture) (ntex x 1)
int* tex_height; // number of rows in texture image (ntex x 1)
int* tex_width; // number of columns in texture image (ntex x 1)
int* tex_adr; // address in rgb (ntex x 1)
mjtByte* tex_rgb; // rgb (alpha = 1) (ntexdata x 1)
int* tex_pathadr; // address of texture asset path; -1: none (ntex x 1)
// materials
int* mat_texid; // texture id; -1: none (nmat x 1)
mjtByte* mat_texuniform; // make texture cube uniform (nmat x 1)
float* mat_texrepeat; // texture repetition for 2d mapping (nmat x 2)
float* mat_emission; // emission (x rgb) (nmat x 1)
float* mat_specular; // specular (x white) (nmat x 1)
float* mat_shininess; // shininess coef (nmat x 1)
float* mat_reflectance; // reflectance (0: disable) (nmat x 1)
float* mat_metallic; // metallic coef (nmat x 1)
float* mat_roughness; // roughness coef (nmat x 1)
float* mat_rgba; // rgba (nmat x 4)
// predefined geom pairs for collision detection; has precedence over exclude
int* pair_dim; // contact dimensionality (npair x 1)
int* pair_geom1; // id of geom1 (npair x 1)
int* pair_geom2; // id of geom2 (npair x 1)
int* pair_signature; // body1 << 16 + body2 (npair x 1)
mjtNum* pair_solref; // solver reference: contact normal (npair x mjNREF)
mjtNum* pair_solreffriction; // solver reference: contact friction (npair x mjNREF)
mjtNum* pair_solimp; // solver impedance: contact (npair x mjNIMP)
mjtNum* pair_margin; // detect contact if dist<margin (npair x 1)
mjtNum* pair_gap; // include in solver if dist<margin-gap (npair x 1)
mjtNum* pair_friction; // tangent1, 2, spin, roll1, 2 (npair x 5)
// excluded body pairs for collision detection
int* exclude_signature; // body1 << 16 + body2 (nexclude x 1)
// equality constraints
int* eq_type; // constraint type (mjtEq) (neq x 1)
int* eq_obj1id; // id of object 1 (neq x 1)
int* eq_obj2id; // id of object 2 (neq x 1)
mjtByte* eq_active0; // initial enable/disable constraint state (neq x 1)
mjtNum* eq_solref; // constraint solver reference (neq x mjNREF)
mjtNum* eq_solimp; // constraint solver impedance (neq x mjNIMP)
mjtNum* eq_data; // numeric data for constraint (neq x mjNEQDATA)
// tendons
int* tendon_adr; // address of first object in tendon's path (ntendon x 1)
int* tendon_num; // number of objects in tendon's path (ntendon x 1)
int* tendon_matid; // material id for rendering (ntendon x 1)
int* tendon_group; // group for visibility (ntendon x 1)
mjtByte* tendon_limited; // does tendon have length limits (ntendon x 1)
mjtNum* tendon_width; // width for rendering (ntendon x 1)
mjtNum* tendon_solref_lim; // constraint solver reference: limit (ntendon x mjNREF)
mjtNum* tendon_solimp_lim; // constraint solver impedance: limit (ntendon x mjNIMP)
mjtNum* tendon_solref_fri; // constraint solver reference: friction (ntendon x mjNREF)
mjtNum* tendon_solimp_fri; // constraint solver impedance: friction (ntendon x mjNIMP)
mjtNum* tendon_range; // tendon length limits (ntendon x 2)
mjtNum* tendon_margin; // min distance for limit detection (ntendon x 1)
mjtNum* tendon_stiffness; // stiffness coefficient (ntendon x 1)
mjtNum* tendon_damping; // damping coefficient (ntendon x 1)
mjtNum* tendon_frictionloss; // loss due to friction (ntendon x 1)
mjtNum* tendon_lengthspring; // spring resting length range (ntendon x 2)
mjtNum* tendon_length0; // tendon length in qpos0 (ntendon x 1)
mjtNum* tendon_invweight0; // inv. weight in qpos0 (ntendon x 1)
mjtNum* tendon_user; // user data (ntendon x nuser_tendon)
float* tendon_rgba; // rgba when material is omitted (ntendon x 4)
// list of all wrap objects in tendon paths
int* wrap_type; // wrap object type (mjtWrap) (nwrap x 1)
int* wrap_objid; // object id: geom, site, joint (nwrap x 1)
mjtNum* wrap_prm; // divisor, joint coef, or site id (nwrap x 1)
// actuators
int* actuator_trntype; // transmission type (mjtTrn) (nu x 1)
int* actuator_dyntype; // dynamics type (mjtDyn) (nu x 1)
int* actuator_gaintype; // gain type (mjtGain) (nu x 1)
int* actuator_biastype; // bias type (mjtBias) (nu x 1)
int* actuator_trnid; // transmission id: joint, tendon, site (nu x 2)
int* actuator_actadr; // first activation address; -1: stateless (nu x 1)
int* actuator_actnum; // number of activation variables (nu x 1)
int* actuator_group; // group for visibility (nu x 1)
mjtByte* actuator_ctrllimited; // is control limited (nu x 1)
mjtByte* actuator_forcelimited;// is force limited (nu x 1)
mjtByte* actuator_actlimited; // is activation limited (nu x 1)
mjtNum* actuator_dynprm; // dynamics parameters (nu x mjNDYN)
mjtNum* actuator_gainprm; // gain parameters (nu x mjNGAIN)
mjtNum* actuator_biasprm; // bias parameters (nu x mjNBIAS)
mjtByte* actuator_actearly; // step activation before force (nu x 1)
mjtNum* actuator_ctrlrange; // range of controls (nu x 2)
mjtNum* actuator_forcerange; // range of forces (nu x 2)
mjtNum* actuator_actrange; // range of activations (nu x 2)
mjtNum* actuator_gear; // scale length and transmitted force (nu x 6)
mjtNum* actuator_cranklength; // crank length for slider-crank (nu x 1)
mjtNum* actuator_acc0; // acceleration from unit force in qpos0 (nu x 1)
mjtNum* actuator_length0; // actuator length in qpos0 (nu x 1)
mjtNum* actuator_lengthrange; // feasible actuator length range (nu x 2)
mjtNum* actuator_user; // user data (nu x nuser_actuator)
int* actuator_plugin; // plugin instance id; -1: not a plugin (nu x 1)
// sensors
int* sensor_type; // sensor type (mjtSensor) (nsensor x 1)
int* sensor_datatype; // numeric data type (mjtDataType) (nsensor x 1)
int* sensor_needstage; // required compute stage (mjtStage) (nsensor x 1)
int* sensor_objtype; // type of sensorized object (mjtObj) (nsensor x 1)
int* sensor_objid; // id of sensorized object (nsensor x 1)
int* sensor_reftype; // type of reference frame (mjtObj) (nsensor x 1)
int* sensor_refid; // id of reference frame; -1: global frame (nsensor x 1)
int* sensor_dim; // number of scalar outputs (nsensor x 1)
int* sensor_adr; // address in sensor array (nsensor x 1)
mjtNum* sensor_cutoff; // cutoff for real and positive; 0: ignore (nsensor x 1)
mjtNum* sensor_noise; // noise standard deviation (nsensor x 1)
mjtNum* sensor_user; // user data (nsensor x nuser_sensor)
int* sensor_plugin; // plugin instance id; -1: not a plugin (nsensor x 1)
// plugin instances
int* plugin; // globally registered plugin slot number (nplugin x 1)
int* plugin_stateadr; // address in the plugin state array (nplugin x 1)
int* plugin_statenum; // number of states in the plugin instance (nplugin x 1)
char* plugin_attr; // config attributes of plugin instances (npluginattr x 1)
int* plugin_attradr; // address to each instance's config attrib (nplugin x 1)
// custom numeric fields
int* numeric_adr; // address of field in numeric_data (nnumeric x 1)
int* numeric_size; // size of numeric field (nnumeric x 1)
mjtNum* numeric_data; // array of all numeric fields (nnumericdata x 1)
// custom text fields
int* text_adr; // address of text in text_data (ntext x 1)
int* text_size; // size of text field (strlen+1) (ntext x 1)
char* text_data; // array of all text fields (0-terminated) (ntextdata x 1)
// custom tuple fields
int* tuple_adr; // address of text in text_data (ntuple x 1)
int* tuple_size; // number of objects in tuple (ntuple x 1)
int* tuple_objtype; // array of object types in all tuples (ntupledata x 1)
int* tuple_objid; // array of object ids in all tuples (ntupledata x 1)
mjtNum* tuple_objprm; // array of object params in all tuples (ntupledata x 1)
// keyframes
mjtNum* key_time; // key time (nkey x 1)
mjtNum* key_qpos; // key position (nkey x nq)
mjtNum* key_qvel; // key velocity (nkey x nv)
mjtNum* key_act; // key activation (nkey x na)
mjtNum* key_mpos; // key mocap position (nkey x 3*nmocap)
mjtNum* key_mquat; // key mocap quaternion (nkey x 4*nmocap)
mjtNum* key_ctrl; // key control (nkey x nu)
// names
int* name_bodyadr; // body name pointers (nbody x 1)
int* name_jntadr; // joint name pointers (njnt x 1)
int* name_geomadr; // geom name pointers (ngeom x 1)
int* name_siteadr; // site name pointers (nsite x 1)
int* name_camadr; // camera name pointers (ncam x 1)
int* name_lightadr; // light name pointers (nlight x 1)
int* name_flexadr; // flex name pointers (nflex x 1)
int* name_meshadr; // mesh name pointers (nmesh x 1)
int* name_skinadr; // skin name pointers (nskin x 1)
int* name_hfieldadr; // hfield name pointers (nhfield x 1)
int* name_texadr; // texture name pointers (ntex x 1)
int* name_matadr; // material name pointers (nmat x 1)
int* name_pairadr; // geom pair name pointers (npair x 1)
int* name_excludeadr; // exclude name pointers (nexclude x 1)
int* name_eqadr; // equality constraint name pointers (neq x 1)
int* name_tendonadr; // tendon name pointers (ntendon x 1)
int* name_actuatoradr; // actuator name pointers (nu x 1)
int* name_sensoradr; // sensor name pointers (nsensor x 1)
int* name_numericadr; // numeric name pointers (nnumeric x 1)
int* name_textadr; // text name pointers (ntext x 1)
int* name_tupleadr; // tuple name pointers (ntuple x 1)
int* name_keyadr; // keyframe name pointers (nkey x 1)
int* name_pluginadr; // plugin instance name pointers (nplugin x 1)
char* names; // names of all objects, 0-terminated (nnames x 1)
int* names_map; // internal hash map of names (nnames_map x 1)
// paths
char* paths; // paths to assets, 0-terminated (npaths x 1)
};
typedef struct mjModel_ mjModel;
mjOption#
This is the data structure with simulation options. It corresponds to the MJCF element option. One instance of it is embedded in mjModel.
struct mjOption_ { // physics options
// timing parameters
mjtNum timestep; // timestep
mjtNum apirate; // update rate for remote API (Hz)
// solver parameters
mjtNum impratio; // ratio of friction-to-normal contact impedance
mjtNum tolerance; // main solver tolerance
mjtNum ls_tolerance; // CG/Newton linesearch tolerance
mjtNum noslip_tolerance; // noslip solver tolerance
mjtNum mpr_tolerance; // MPR solver tolerance
// physical constants
mjtNum gravity[3]; // gravitational acceleration
mjtNum wind[3]; // wind (for lift, drag and viscosity)
mjtNum magnetic[3]; // global magnetic flux
mjtNum density; // density of medium
mjtNum viscosity; // viscosity of medium
// override contact solver parameters (if enabled)
mjtNum o_margin; // margin
mjtNum o_solref[mjNREF]; // solref
mjtNum o_solimp[mjNIMP]; // solimp
mjtNum o_friction[5]; // friction
// discrete settings
int integrator; // integration mode (mjtIntegrator)
int cone; // type of friction cone (mjtCone)
int jacobian; // type of Jacobian (mjtJacobian)
int solver; // solver algorithm (mjtSolver)
int iterations; // maximum number of main solver iterations
int ls_iterations; // maximum number of CG/Newton linesearch iterations
int noslip_iterations; // maximum number of noslip solver iterations
int mpr_iterations; // maximum number of MPR solver iterations
int disableflags; // bit flags for disabling standard features
int enableflags; // bit flags for enabling optional features
int disableactuator; // bit flags for disabling actuators by group id
// sdf collision settings
int sdf_initpoints; // number of starting points for gradient descent
int sdf_iterations; // max number of iterations for gradient descent
};
typedef struct mjOption_ mjOption;
mjData#
This is the main data structure holding the simulation state. It is the workspace where all functions read their modifiable inputs and write their outputs.
struct mjData_ {
// constant sizes
size_t narena; // size of the arena in bytes (inclusive of the stack)
size_t nbuffer; // size of main buffer in bytes
int nplugin; // number of plugin instances
// stack pointer
size_t pstack; // first available mjtNum address in stack
size_t pbase; // value of pstack when mj_markStack was last called
// arena pointer
size_t parena; // first available byte in arena
// memory utilization stats
size_t maxuse_stack; // maximum stack allocation in bytes
size_t maxuse_threadstack[mjMAXTHREAD]; // maximum stack allocation per thread in bytes
size_t maxuse_arena; // maximum arena allocation in bytes
int maxuse_con; // maximum number of contacts
int maxuse_efc; // maximum number of scalar constraints
// diagnostics
mjWarningStat warning[mjNWARNING]; // warning statistics
mjTimerStat timer[mjNTIMER]; // timer statistics
// solver statistics
mjSolverStat solver[mjNISLAND*mjNSOLVER]; // solver statistics per island, per iteration
int solver_nisland; // number of islands processed by solver
int solver_niter[mjNISLAND]; // number of solver iterations, per island
int solver_nnz[mjNISLAND]; // number of non-zeros in Hessian or efc_AR, per island
mjtNum solver_fwdinv[2]; // forward-inverse comparison: qfrc, efc
// variable sizes
int ne; // number of equality constraints
int nf; // number of friction constraints
int nl; // number of limit constraints
int nefc; // number of constraints
int nnzJ; // number of non-zeros in constraint Jacobian
int ncon; // number of detected contacts
int nisland; // number of detected constraint islands
// global properties
mjtNum time; // simulation time
mjtNum energy[2]; // potential, kinetic energy
//-------------------- end of info header
// buffers
void* buffer; // main buffer; all pointers point in it (nbuffer bytes)
void* arena; // arena+stack buffer (nstack*sizeof(mjtNum) bytes)
//-------------------- main inputs and outputs of the computation
// state
mjtNum* qpos; // position (nq x 1)
mjtNum* qvel; // velocity (nv x 1)
mjtNum* act; // actuator activation (na x 1)
mjtNum* qacc_warmstart; // acceleration used for warmstart (nv x 1)
mjtNum* plugin_state; // plugin state (npluginstate x 1)
// control
mjtNum* ctrl; // control (nu x 1)
mjtNum* qfrc_applied; // applied generalized force (nv x 1)
mjtNum* xfrc_applied; // applied Cartesian force/torque (nbody x 6)
mjtByte* eq_active; // enable/disable constraints (neq x 1)
// mocap data
mjtNum* mocap_pos; // positions of mocap bodies (nmocap x 3)
mjtNum* mocap_quat; // orientations of mocap bodies (nmocap x 4)
// dynamics
mjtNum* qacc; // acceleration (nv x 1)
mjtNum* act_dot; // time-derivative of actuator activation (na x 1)
// user data
mjtNum* userdata; // user data, not touched by engine (nuserdata x 1)
// sensors
mjtNum* sensordata; // sensor data array (nsensordata x 1)
// plugins
int* plugin; // copy of m->plugin, required for deletion (nplugin x 1)
uintptr_t* plugin_data; // pointer to plugin-managed data structure (nplugin x 1)
//-------------------- POSITION dependent
// computed by mj_fwdPosition/mj_kinematics
mjtNum* xpos; // Cartesian position of body frame (nbody x 3)
mjtNum* xquat; // Cartesian orientation of body frame (nbody x 4)
mjtNum* xmat; // Cartesian orientation of body frame (nbody x 9)
mjtNum* xipos; // Cartesian position of body com (nbody x 3)
mjtNum* ximat; // Cartesian orientation of body inertia (nbody x 9)
mjtNum* xanchor; // Cartesian position of joint anchor (njnt x 3)
mjtNum* xaxis; // Cartesian joint axis (njnt x 3)
mjtNum* geom_xpos; // Cartesian geom position (ngeom x 3)
mjtNum* geom_xmat; // Cartesian geom orientation (ngeom x 9)
mjtNum* site_xpos; // Cartesian site position (nsite x 3)
mjtNum* site_xmat; // Cartesian site orientation (nsite x 9)
mjtNum* cam_xpos; // Cartesian camera position (ncam x 3)
mjtNum* cam_xmat; // Cartesian camera orientation (ncam x 9)
mjtNum* light_xpos; // Cartesian light position (nlight x 3)
mjtNum* light_xdir; // Cartesian light direction (nlight x 3)
// computed by mj_fwdPosition/mj_comPos
mjtNum* subtree_com; // center of mass of each subtree (nbody x 3)
mjtNum* cdof; // com-based motion axis of each dof (rot:lin) (nv x 6)
mjtNum* cinert; // com-based body inertia and mass (nbody x 10)
// computed by mj_fwdPosition/mj_flex
mjtNum* flexvert_xpos; // Cartesian flex vertex positions (nflexvert x 3)
mjtNum* flexelem_aabb; // flex element bounding boxes (center, size) (nflexelem x 6)
int* flexedge_J_rownnz; // number of non-zeros in Jacobian row (nflexedge x 1)
int* flexedge_J_rowadr; // row start address in colind array (nflexedge x 1)
int* flexedge_J_colind; // column indices in sparse Jacobian (nflexedge x nv)
mjtNum* flexedge_J; // flex edge Jacobian (nflexedge x nv)
mjtNum* flexedge_length; // flex edge lengths (nflexedge x 1)
// computed by mj_fwdPosition/mj_tendon
int* ten_wrapadr; // start address of tendon's path (ntendon x 1)
int* ten_wrapnum; // number of wrap points in path (ntendon x 1)
int* ten_J_rownnz; // number of non-zeros in Jacobian row (ntendon x 1)
int* ten_J_rowadr; // row start address in colind array (ntendon x 1)
int* ten_J_colind; // column indices in sparse Jacobian (ntendon x nv)
mjtNum* ten_J; // tendon Jacobian (ntendon x nv)
mjtNum* ten_length; // tendon lengths (ntendon x 1)
int* wrap_obj; // geom id; -1: site; -2: pulley (nwrap*2 x 1)
mjtNum* wrap_xpos; // Cartesian 3D points in all path (nwrap*2 x 3)
// computed by mj_fwdPosition/mj_transmission
mjtNum* actuator_length; // actuator lengths (nu x 1)
mjtNum* actuator_moment; // actuator moments (nu x nv)
// computed by mj_fwdPosition/mj_crb
mjtNum* crb; // com-based composite inertia and mass (nbody x 10)
mjtNum* qM; // total inertia (sparse) (nM x 1)
// computed by mj_fwdPosition/mj_factorM
mjtNum* qLD; // L'*D*L factorization of M (sparse) (nM x 1)
mjtNum* qLDiagInv; // 1/diag(D) (nv x 1)
mjtNum* qLDiagSqrtInv; // 1/sqrt(diag(D)) (nv x 1)
// computed by mj_collisionTree
mjtNum* bvh_aabb_dyn; // global bounding box (center, size) (nbvhdynamic x 6)
mjtByte* bvh_active; // volume has been added to collisions (nbvh x 1)
//-------------------- POSITION, VELOCITY dependent
// computed by mj_fwdVelocity
mjtNum* flexedge_velocity; // flex edge velocities (nflexedge x 1)
mjtNum* ten_velocity; // tendon velocities (ntendon x 1)
mjtNum* actuator_velocity; // actuator velocities (nu x 1)
// computed by mj_fwdVelocity/mj_comVel
mjtNum* cvel; // com-based velocity (rot:lin) (nbody x 6)
mjtNum* cdof_dot; // time-derivative of cdof (rot:lin) (nv x 6)
// computed by mj_fwdVelocity/mj_rne (without acceleration)
mjtNum* qfrc_bias; // C(qpos,qvel) (nv x 1)
// computed by mj_fwdVelocity/mj_passive
mjtNum* qfrc_spring; // passive spring force (nv x 1)
mjtNum* qfrc_damper; // passive damper force (nv x 1)
mjtNum* qfrc_gravcomp; // passive gravity compensation force (nv x 1)
mjtNum* qfrc_fluid; // passive fluid force (nv x 1)
mjtNum* qfrc_passive; // total passive force (nv x 1)
// computed by mj_sensorVel/mj_subtreeVel if needed
mjtNum* subtree_linvel; // linear velocity of subtree com (nbody x 3)
mjtNum* subtree_angmom; // angular momentum about subtree com (nbody x 3)
// computed by mj_Euler or mj_implicit
mjtNum* qH; // L'*D*L factorization of modified M (nM x 1)
mjtNum* qHDiagInv; // 1/diag(D) of modified M (nv x 1)
// computed by mj_resetData
int* D_rownnz; // non-zeros in each row (nv x 1)
int* D_rowadr; // address of each row in D_colind (nv x 1)
int* D_colind; // column indices of non-zeros (nD x 1)
int* B_rownnz; // non-zeros in each row (nbody x 1)
int* B_rowadr; // address of each row in B_colind (nbody x 1)
int* B_colind; // column indices of non-zeros (nB x 1)
// computed by mj_implicit/mj_derivative
mjtNum* qDeriv; // d (passive + actuator - bias) / d qvel (nD x 1)
// computed by mj_implicit/mju_factorLUSparse
mjtNum* qLU; // sparse LU of (qM - dt*qDeriv) (nD x 1)
//-------------------- POSITION, VELOCITY, CONTROL/ACCELERATION dependent
// computed by mj_fwdActuation
mjtNum* actuator_force; // actuator force in actuation space (nu x 1)
mjtNum* qfrc_actuator; // actuator force (nv x 1)
// computed by mj_fwdAcceleration
mjtNum* qfrc_smooth; // net unconstrained force (nv x 1)
mjtNum* qacc_smooth; // unconstrained acceleration (nv x 1)
// computed by mj_fwdConstraint/mj_inverse
mjtNum* qfrc_constraint; // constraint force (nv x 1)
// computed by mj_inverse
mjtNum* qfrc_inverse; // net external force; should equal: (nv x 1)
// qfrc_applied + J'*xfrc_applied + qfrc_actuator
// computed by mj_sensorAcc/mj_rnePostConstraint if needed; rotation:translation format
mjtNum* cacc; // com-based acceleration (nbody x 6)
mjtNum* cfrc_int; // com-based interaction force with parent (nbody x 6)
mjtNum* cfrc_ext; // com-based external force on body (nbody x 6)
//-------------------- arena-allocated: POSITION dependent
// computed by mj_collision
mjContact* contact; // list of all detected contacts (ncon x 1)
// computed by mj_makeConstraint
int* efc_type; // constraint type (mjtConstraint) (nefc x 1)
int* efc_id; // id of object of specified type (nefc x 1)
int* efc_J_rownnz; // number of non-zeros in constraint Jacobian row (nefc x 1)
int* efc_J_rowadr; // row start address in colind array (nefc x 1)
int* efc_J_rowsuper; // number of subsequent rows in supernode (nefc x 1)
int* efc_J_colind; // column indices in constraint Jacobian (nnzJ x 1)
int* efc_JT_rownnz; // number of non-zeros in constraint Jacobian row T (nv x 1)
int* efc_JT_rowadr; // row start address in colind array T (nv x 1)
int* efc_JT_rowsuper; // number of subsequent rows in supernode T (nv x 1)
int* efc_JT_colind; // column indices in constraint Jacobian T (nnzJ x 1)
mjtNum* efc_J; // constraint Jacobian (nnzJ x 1)
mjtNum* efc_JT; // constraint Jacobian transposed (nnzJ x 1)
mjtNum* efc_pos; // constraint position (equality, contact) (nefc x 1)
mjtNum* efc_margin; // inclusion margin (contact) (nefc x 1)
mjtNum* efc_frictionloss; // frictionloss (friction) (nefc x 1)
mjtNum* efc_diagApprox; // approximation to diagonal of A (nefc x 1)
mjtNum* efc_KBIP; // stiffness, damping, impedance, imp' (nefc x 4)
mjtNum* efc_D; // constraint mass (nefc x 1)
mjtNum* efc_R; // inverse constraint mass (nefc x 1)
int* tendon_efcadr; // first efc address involving tendon; -1: none (ntendon x 1)
// computed by mj_island
int* dof_island; // island id of this dof; -1: none (nv x 1)
int* island_dofnum; // number of dofs in island (nisland x 1)
int* island_dofadr; // start address in island_dofind (nisland x 1)
int* island_dofind; // island dof indices; -1: none (nv x 1)
int* dof_islandind; // dof island indices; -1: none (nv x 1)
int* efc_island; // island id of this constraint (nefc x 1)
int* island_efcnum; // number of constraints in island (nisland x 1)
int* island_efcadr; // start address in island_efcind (nisland x 1)
int* island_efcind; // island constraint indices (nefc x 1)
// computed by mj_projectConstraint (dual solver)
int* efc_AR_rownnz; // number of non-zeros in AR (nefc x 1)
int* efc_AR_rowadr; // row start address in colind array (nefc x 1)
int* efc_AR_colind; // column indices in sparse AR (nefc x nefc)
mjtNum* efc_AR; // J*inv(M)*J' + R (nefc x nefc)
//-------------------- arena-allocated: POSITION, VELOCITY dependent
// computed by mj_fwdVelocity/mj_referenceConstraint
mjtNum* efc_vel; // velocity in constraint space: J*qvel (nefc x 1)
mjtNum* efc_aref; // reference pseudo-acceleration (nefc x 1)
//-------------------- arena-allocated: POSITION, VELOCITY, CONTROL/ACCELERATION dependent
// computed by mj_fwdConstraint/mj_inverse
mjtNum* efc_b; // linear cost term: J*qacc_smooth - aref (nefc x 1)
mjtNum* efc_force; // constraint force in constraint space (nefc x 1)
int* efc_state; // constraint state (mjtConstraintState) (nefc x 1)
// ThreadPool for multithreaded operations
uintptr_t threadpool;
};
typedef struct mjData_ mjData;
Auxillary#
These struct types are used in the engine and their names are prefixed with mj. mjVisual
and mjStatistic are embedded in mjModel, mjContact is embedded in mjData, and mjVFS
is a library-level struct used for loading assets.
mjVisual#
This is the data structure with abstract visualization options. It corresponds to the MJCF element visual. One instance of it is embedded in mjModel.
struct mjVisual_ { // visualization options
struct { // global parameters
float fovy; // y-field of view for free camera (degrees)
float ipd; // inter-pupilary distance for free camera
float azimuth; // initial azimuth of free camera (degrees)
float elevation; // initial elevation of free camera (degrees)
float linewidth; // line width for wireframe and ray rendering
float glow; // glow coefficient for selected body
float realtime; // initial real-time factor (1: real time)
int offwidth; // width of offscreen buffer
int offheight; // height of offscreen buffer
int ellipsoidinertia; // geom for inertia visualization (0: box, 1: ellipsoid)
int bvactive; // visualize active bounding volumes (0: no, 1: yes)
} global;
struct { // rendering quality
int shadowsize; // size of shadowmap texture
int offsamples; // number of multisamples for offscreen rendering
int numslices; // number of slices for builtin geom drawing
int numstacks; // number of stacks for builtin geom drawing
int numquads; // number of quads for box rendering
} quality;
struct { // head light
float ambient[3]; // ambient rgb (alpha=1)
float diffuse[3]; // diffuse rgb (alpha=1)
float specular[3]; // specular rgb (alpha=1)
int active; // is headlight active
} headlight;
struct { // mapping
float stiffness; // mouse perturbation stiffness (space->force)
float stiffnessrot; // mouse perturbation stiffness (space->torque)
float force; // from force units to space units
float torque; // from torque units to space units
float alpha; // scale geom alphas when transparency is enabled
float fogstart; // OpenGL fog starts at fogstart * mjModel.stat.extent
float fogend; // OpenGL fog ends at fogend * mjModel.stat.extent
float znear; // near clipping plane = znear * mjModel.stat.extent
float zfar; // far clipping plane = zfar * mjModel.stat.extent
float haze; // haze ratio
float shadowclip; // directional light: shadowclip * mjModel.stat.extent
float shadowscale; // spot light: shadowscale * light.cutoff
float actuatortendon; // scale tendon width
} map;
struct { // scale of decor elements relative to mean body size
float forcewidth; // width of force arrow
float contactwidth; // contact width
float contactheight; // contact height
float connect; // autoconnect capsule width
float com; // com radius
float camera; // camera object
float light; // light object
float selectpoint; // selection point
float jointlength; // joint length
float jointwidth; // joint width
float actuatorlength; // actuator length
float actuatorwidth; // actuator width
float framelength; // bodyframe axis length
float framewidth; // bodyframe axis width
float constraint; // constraint width
float slidercrank; // slidercrank width
float frustum; // frustum zfar plane
} scale;
struct { // color of decor elements
float fog[4]; // fog
float haze[4]; // haze
float force[4]; // external force
float inertia[4]; // inertia box
float joint[4]; // joint
float actuator[4]; // actuator, neutral
float actuatornegative[4]; // actuator, negative limit
float actuatorpositive[4]; // actuator, positive limit
float com[4]; // center of mass
float camera[4]; // camera object
float light[4]; // light object
float selectpoint[4]; // selection point
float connect[4]; // auto connect
float contactpoint[4]; // contact point
float contactforce[4]; // contact force
float contactfriction[4]; // contact friction force
float contacttorque[4]; // contact torque
float contactgap[4]; // contact point in gap
float rangefinder[4]; // rangefinder ray
float constraint[4]; // constraint
float slidercrank[4]; // slidercrank
float crankbroken[4]; // used when crank must be stretched/broken
float frustum[4]; // camera frustum
float bv[4]; // bounding volume
float bvactive[4]; // active bounding volume
} rgba;
};
typedef struct mjVisual_ mjVisual;
mjStatistic#
This is the data structure with model statistics precomputed by the compiler or set by the user. It corresponds to the MJCF element statistic. One instance of it is embedded in mjModel.
struct mjStatistic_ { // model statistics (in qpos0)
mjtNum meaninertia; // mean diagonal inertia
mjtNum meanmass; // mean body mass
mjtNum meansize; // mean body size
mjtNum extent; // spatial extent
mjtNum center[3]; // center of model
};
typedef struct mjStatistic_ mjStatistic;
mjContact#
This is the data structure holding information about one contact. mjData.contact is a preallocated array of
mjContact data structures, populated at runtime with the contacts found by the collision detector. Additional contact
information is then filled-in by the simulator.
struct mjContact_ { // result of collision detection functions
// contact parameters set by near-phase collision function
mjtNum dist; // distance between nearest points; neg: penetration
mjtNum pos[3]; // position of contact point: midpoint between geoms
mjtNum frame[9]; // normal is in [0-2], points from geom[0] to geom[1]
// contact parameters set by mj_collideGeoms
mjtNum includemargin; // include if dist<includemargin=margin-gap
mjtNum friction[5]; // tangent1, 2, spin, roll1, 2
mjtNum solref[mjNREF]; // constraint solver reference, normal direction
mjtNum solreffriction[mjNREF]; // constraint solver reference, friction directions
mjtNum solimp[mjNIMP]; // constraint solver impedance
// internal storage used by solver
mjtNum mu; // friction of regularized cone, set by mj_makeConstraint
mjtNum H[36]; // cone Hessian, set by mj_updateConstraint
// contact descriptors set by mj_collideXXX
int dim; // contact space dimensionality: 1, 3, 4 or 6
int geom1; // id of geom 1; deprecated, use geom[0]
int geom2; // id of geom 2; deprecated, use geom[1]
int geom[2]; // geom ids; -1 for flex
int flex[2]; // flex ids; -1 for geom
int elem[2]; // element ids; -1 for geom or flex vertex
int vert[2]; // vertex ids; -1 for geom or flex element
// flag set by mj_setContact or mj_instantiateContact
int exclude; // 0: include, 1: in gap, 2: fused, 3: no dofs
// address computed by mj_instantiateContact
int efc_address; // address in efc; -1: not included
};
typedef struct mjContact_ mjContact;
mjResource#
A resource is an abstraction of a file in a filesystem. The name field is the unique name of the resource while the other fields are populated by a resource provider.
struct mjResource_ {
char* name; // name of resource (filename, etc)
void* data; // opaque data pointer
char timestamp[512]; // timestamp of the resource
const struct mjpResourceProvider* provider; // pointer to the provider
};
typedef struct mjResource_ mjResource;
mjVFS#
This is the data structure of the virtual file system. It can only be constructed programmatically, and does not have an analog in MJCF.
struct mjVFS_ { // virtual file system for loading from memory
int nfile; // number of files present
char filename[mjMAXVFS][mjMAXVFSNAME]; // file name without path
size_t filesize[mjMAXVFS]; // file size in bytes
void* filedata[mjMAXVFS]; // buffer with file data
uint64_t filestamp[mjMAXVFS]; // checksum of the file data
};
typedef struct mjVFS_ mjVFS;
mjLROpt#
Options for configuring the automatic actuator length-range computation.
struct mjLROpt_ { // options for mj_setLengthRange()
// flags
int mode; // which actuators to process (mjtLRMode)
int useexisting; // use existing length range if available
int uselimit; // use joint and tendon limits if available
// algorithm parameters
mjtNum accel; // target acceleration used to compute force
mjtNum maxforce; // maximum force; 0: no limit
mjtNum timeconst; // time constant for velocity reduction; min 0.01
mjtNum timestep; // simulation timestep; 0: use mjOption.timestep
mjtNum inttotal; // total simulation time interval
mjtNum interval; // evaluation time interval (at the end)
mjtNum tolrange; // convergence tolerance (relative to range)
};
typedef struct mjLROpt_ mjLROpt;
mjTask#
This is a representation of a task to be run asynchronously inside of an mjThreadPool . It is created in the mju_threadPoolEnqueue method of the mjThreadPool and is used to join the task at completion.
struct mjTask_ { // a task that can be executed by a thread pool.
mjfTask func; // pointer to the function that implements the task
void* args; // arguments to func
volatile int status; // status of the task
};
typedef struct mjTask_ mjTask;
mjThreadPool#
This is the data structure of the threadpool. It can only be constructed programmatically, and does not
have an analog in MJCF. In order to enable multi-threaded calculations, a pointer to an existing mjThreadPool
should be assigned to the mjData.threadpool.
struct mjThreadPool_ {
int nworker; // number of workers in the pool
};
typedef struct mjThreadPool_ mjThreadPool;
Sim statistics#
These structs are all embedded in mjData, and collect simulation-related statistics.
mjWarningStat#
This is the data structure holding information about one warning type. mjData.warning is a preallocated array of
mjWarningStat data structures, one for each warning type.
struct mjWarningStat_ { // warning statistics
int lastinfo; // info from last warning
int number; // how many times was warning raised
};
typedef struct mjWarningStat_ mjWarningStat;
mjTimerStat#
This is the data structure holding information about one timer. mjData.timer is a preallocated array of
mjTimerStat data structures, one for each timer type.
struct mjTimerStat_ { // timer statistics
mjtNum duration; // cumulative duration
int number; // how many times was timer called
};
typedef struct mjTimerStat_ mjTimerStat;
mjSolverStat#
This is the data structure holding information about one solver iteration. mjData.solver is a preallocated array
of mjSolverStat data structures, one for each iteration of the solver, up to a maximum of mjNSOLVER. The actual number
of solver iterations is given by mjData.solver_iter.
struct mjSolverStat_ { // per-iteration solver statistics
mjtNum improvement; // cost reduction, scaled by 1/trace(M(qpos0))
mjtNum gradient; // gradient norm (primal only, scaled)
mjtNum lineslope; // slope in linesearch
int nactive; // number of active constraints
int nchange; // number of constraint state changes
int neval; // number of cost evaluations in line search
int nupdate; // number of Cholesky updates in line search
};
typedef struct mjSolverStat_ mjSolverStat;
Visualisation#
The names of these struct types are prefixed with mjv.
mjvPerturb#
This is the data structure holding information about mouse perturbations.
struct mjvPerturb_ { // object selection and perturbation
int select; // selected body id; non-positive: none
int flexselect; // selected flex id; negative: none
int skinselect; // selected skin id; negative: none
int active; // perturbation bitmask (mjtPertBit)
int active2; // secondary perturbation bitmask (mjtPertBit)
mjtNum refpos[3]; // reference position for selected object
mjtNum refquat[4]; // reference orientation for selected object
mjtNum refselpos[3]; // reference position for selection point
mjtNum localpos[3]; // selection point in object coordinates
mjtNum localmass; // spatial inertia at selection point
mjtNum scale; // relative mouse motion-to-space scaling (set by initPerturb)
};
typedef struct mjvPerturb_ mjvPerturb;
mjvCamera#
This is the data structure describing one abstract camera.
struct mjvCamera_ { // abstract camera
// type and ids
int type; // camera type (mjtCamera)
int fixedcamid; // fixed camera id
int trackbodyid; // body id to track
// abstract camera pose specification
mjtNum lookat[3]; // lookat point
mjtNum distance; // distance to lookat point or tracked body
mjtNum azimuth; // camera azimuth (deg)
mjtNum elevation; // camera elevation (deg)
};
typedef struct mjvCamera_ mjvCamera;
mjvGLCamera#
This is the data structure describing one OpenGL camera.
struct mjvGLCamera_ { // OpenGL camera
// camera frame
float pos[3]; // position
float forward[3]; // forward direction
float up[3]; // up direction
// camera projection
float frustum_center; // hor. center (left,right set to match aspect)
float frustum_width; // width (not used for rendering)
float frustum_bottom; // bottom
float frustum_top; // top
float frustum_near; // near
float frustum_far; // far
};
typedef struct mjvGLCamera_ mjvGLCamera;
mjvGeom#
This is the data structure describing one abstract visualization geom - which could correspond to a model geom or to a decoration element constructed by the visualizer.
struct mjvGeom_ { // abstract geom
// type info
int type; // geom type (mjtGeom)
int dataid; // mesh, hfield or plane id; -1: none
int objtype; // mujoco object type; mjOBJ_UNKNOWN for decor
int objid; // mujoco object id; -1 for decor
int category; // visual category
int texid; // texture id; -1: no texture
int texuniform; // uniform cube mapping
int texcoord; // mesh or flex geom has texture coordinates
int segid; // segmentation id; -1: not shown
// OpenGL info
float texrepeat[2]; // texture repetition for 2D mapping
float size[3]; // size parameters
float pos[3]; // Cartesian position
float mat[9]; // Cartesian orientation
float rgba[4]; // color and transparency
float emission; // emission coef
float specular; // specular coef
float shininess; // shininess coef
float reflectance; // reflectance coef
char label[100]; // text label
// transparency rendering (set internally)
float camdist; // distance to camera (used by sorter)
float modelrbound; // geom rbound from model, 0 if not model geom
mjtByte transparent; // treat geom as transparent
};
typedef struct mjvGeom_ mjvGeom;
mjvLight#
This is the data structure describing one OpenGL light.
struct mjvLight_ { // OpenGL light
float pos[3]; // position rel. to body frame
float dir[3]; // direction rel. to body frame
float attenuation[3]; // OpenGL attenuation (quadratic model)
float cutoff; // OpenGL cutoff
float exponent; // OpenGL exponent
float ambient[3]; // ambient rgb (alpha=1)
float diffuse[3]; // diffuse rgb (alpha=1)
float specular[3]; // specular rgb (alpha=1)
mjtByte headlight; // headlight
mjtByte directional; // directional light
mjtByte castshadow; // does light cast shadows
float bulbradius; // bulb radius for soft shadows
};
typedef struct mjvLight_ mjvLight;
mjvOption#
This structure contains options that enable and disable the visualization of various elements.
struct mjvOption_ { // abstract visualization options
int label; // what objects to label (mjtLabel)
int frame; // which frame to show (mjtFrame)
mjtByte geomgroup[mjNGROUP]; // geom visualization by group
mjtByte sitegroup[mjNGROUP]; // site visualization by group
mjtByte jointgroup[mjNGROUP]; // joint visualization by group
mjtByte tendongroup[mjNGROUP]; // tendon visualization by group
mjtByte actuatorgroup[mjNGROUP]; // actuator visualization by group
mjtByte flexgroup[mjNGROUP]; // flex visualization by group
mjtByte skingroup[mjNGROUP]; // skin visualization by group
mjtByte flags[mjNVISFLAG]; // visualization flags (indexed by mjtVisFlag)
int bvh_depth; // depth of the bounding volume hierarchy to be visualized
int flex_layer; // element layer to be visualized for 3D flex
};
typedef struct mjvOption_ mjvOption;
mjvScene#
This structure contains everything needed to render the 3D scene in OpenGL.
struct mjvScene_ { // abstract scene passed to OpenGL renderer
// abstract geoms
int maxgeom; // size of allocated geom buffer
int ngeom; // number of geoms currently in buffer
mjvGeom* geoms; // buffer for geoms (ngeom)
int* geomorder; // buffer for ordering geoms by distance to camera (ngeom)
// flex data
int nflex; // number of flexes
int* flexedgeadr; // address of flex edges (nflex)
int* flexedgenum; // number of edges in flex (nflex)
int* flexvertadr; // address of flex vertices (nflex)
int* flexvertnum; // number of vertices in flex (nflex)
int* flexfaceadr; // address of flex faces (nflex)
int* flexfacenum; // number of flex faces allocated (nflex)
int* flexfaceused; // number of flex faces currently in use (nflex)
int* flexedge; // flex edge data (2*nflexedge)
float* flexvert; // flex vertices (3*nflexvert)
float* flexface; // flex faces vertices (9*sum(flexfacenum))
float* flexnormal; // flex face normals (9*sum(flexfacenum))
float* flextexcoord; // flex face texture coordinates (6*sum(flexfacenum))
mjtByte flexvertopt; // copy of mjVIS_FLEXVERT mjvOption flag
mjtByte flexedgeopt; // copy of mjVIS_FLEXEDGE mjvOption flag
mjtByte flexfaceopt; // copy of mjVIS_FLEXFACE mjvOption flag
mjtByte flexskinopt; // copy of mjVIS_FLEXSKIN mjvOption flag
// skin data
int nskin; // number of skins
int* skinfacenum; // number of faces in skin (nskin)
int* skinvertadr; // address of skin vertices (nskin)
int* skinvertnum; // number of vertices in skin (nskin)
float* skinvert; // skin vertex data (3*nskinvert)
float* skinnormal; // skin normal data (3*nskinvert)
// OpenGL lights
int nlight; // number of lights currently in buffer
mjvLight lights[mjMAXLIGHT]; // buffer for lights (nlight)
// OpenGL cameras
mjvGLCamera camera[2]; // left and right camera
// OpenGL model transformation
mjtByte enabletransform; // enable model transformation
float translate[3]; // model translation
float rotate[4]; // model quaternion rotation
float scale; // model scaling
// OpenGL rendering effects
int stereo; // stereoscopic rendering (mjtStereo)
mjtByte flags[mjNRNDFLAG]; // rendering flags (indexed by mjtRndFlag)
// framing
int framewidth; // frame pixel width; 0: disable framing
float framergb[3]; // frame color
};
typedef struct mjvScene_ mjvScene;
mjvSceneState#
This structure contains the portions of mjModel and mjData that are required for
various mjv_* functions.
struct mjvScene_ { // abstract scene passed to OpenGL renderer
// abstract geoms
int maxgeom; // size of allocated geom buffer
int ngeom; // number of geoms currently in buffer
mjvGeom* geoms; // buffer for geoms (ngeom)
int* geomorder; // buffer for ordering geoms by distance to camera (ngeom)
// flex data
int nflex; // number of flexes
int* flexedgeadr; // address of flex edges (nflex)
int* flexedgenum; // number of edges in flex (nflex)
int* flexvertadr; // address of flex vertices (nflex)
int* flexvertnum; // number of vertices in flex (nflex)
int* flexfaceadr; // address of flex faces (nflex)
int* flexfacenum; // number of flex faces allocated (nflex)
int* flexfaceused; // number of flex faces currently in use (nflex)
int* flexedge; // flex edge data (2*nflexedge)
float* flexvert; // flex vertices (3*nflexvert)
float* flexface; // flex faces vertices (9*sum(flexfacenum))
float* flexnormal; // flex face normals (9*sum(flexfacenum))
float* flextexcoord; // flex face texture coordinates (6*sum(flexfacenum))
mjtByte flexvertopt; // copy of mjVIS_FLEXVERT mjvOption flag
mjtByte flexedgeopt; // copy of mjVIS_FLEXEDGE mjvOption flag
mjtByte flexfaceopt; // copy of mjVIS_FLEXFACE mjvOption flag
mjtByte flexskinopt; // copy of mjVIS_FLEXSKIN mjvOption flag
// skin data
int nskin; // number of skins
int* skinfacenum; // number of faces in skin (nskin)
int* skinvertadr; // address of skin vertices (nskin)
int* skinvertnum; // number of vertices in skin (nskin)
float* skinvert; // skin vertex data (3*nskinvert)
float* skinnormal; // skin normal data (3*nskinvert)
// OpenGL lights
int nlight; // number of lights currently in buffer
mjvLight lights[mjMAXLIGHT]; // buffer for lights (nlight)
// OpenGL cameras
mjvGLCamera camera[2]; // left and right camera
// OpenGL model transformation
mjtByte enabletransform; // enable model transformation
float translate[3]; // model translation
float rotate[4]; // model quaternion rotation
float scale; // model scaling
// OpenGL rendering effects
int stereo; // stereoscopic rendering (mjtStereo)
mjtByte flags[mjNRNDFLAG]; // rendering flags (indexed by mjtRndFlag)
// framing
int framewidth; // frame pixel width; 0: disable framing
float framergb[3]; // frame color
};
typedef struct mjvScene_ mjvScene;
mjvFigure#
This structure contains everything needed to render a 2D plot in OpenGL. The buffers for line points etc. are preallocated, and the user has to populate them before calling the function mjr_figure with this data structure as an argument.
struct mjvFigure_ { // abstract 2D figure passed to OpenGL renderer
// enable flags
int flg_legend; // show legend
int flg_ticklabel[2]; // show grid tick labels (x,y)
int flg_extend; // automatically extend axis ranges to fit data
int flg_barplot; // isolated line segments (i.e. GL_LINES)
int flg_selection; // vertical selection line
int flg_symmetric; // symmetric y-axis
// style settings
float linewidth; // line width
float gridwidth; // grid line width
int gridsize[2]; // number of grid points in (x,y)
float gridrgb[3]; // grid line rgb
float figurergba[4]; // figure color and alpha
float panergba[4]; // pane color and alpha
float legendrgba[4]; // legend color and alpha
float textrgb[3]; // text color
float linergb[mjMAXLINE][3]; // line colors
float range[2][2]; // axis ranges; (min>=max) automatic
char xformat[20]; // x-tick label format for sprintf
char yformat[20]; // y-tick label format for sprintf
char minwidth[20]; // string used to determine min y-tick width
// text labels
char title[1000]; // figure title; subplots separated with 2+ spaces
char xlabel[100]; // x-axis label
char linename[mjMAXLINE][100]; // line names for legend
// dynamic settings
int legendoffset; // number of lines to offset legend
int subplot; // selected subplot (for title rendering)
int highlight[2]; // if point is in legend rect, highlight line
int highlightid; // if id>=0 and no point, highlight id
float selection; // selection line x-value
// line data
int linepnt[mjMAXLINE]; // number of points in line; (0) disable
float linedata[mjMAXLINE][2*mjMAXLINEPNT]; // line data (x,y)
// output from renderer
int xaxispixel[2]; // range of x-axis in pixels
int yaxispixel[2]; // range of y-axis in pixels
float xaxisdata[2]; // range of x-axis in data units
float yaxisdata[2]; // range of y-axis in data units
};
typedef struct mjvFigure_ mjvFigure;
Rendering#
The names of these struct types are prefixed with mjr.
mjrRect#
This structure specifies a rectangle.
struct mjrRect_ { // OpenGL rectangle
int left; // left (usually 0)
int bottom; // bottom (usually 0)
int width; // width (usually buffer width)
int height; // height (usually buffer height)
};
typedef struct mjrRect_ mjrRect;
mjrContext#
This structure contains the custom OpenGL rendering context, with the ids of all OpenGL resources uploaded to the GPU.
struct mjrContext_ { // custom OpenGL context
// parameters copied from mjVisual
float lineWidth; // line width for wireframe rendering
float shadowClip; // clipping radius for directional lights
float shadowScale; // fraction of light cutoff for spot lights
float fogStart; // fog start = stat.extent * vis.map.fogstart
float fogEnd; // fog end = stat.extent * vis.map.fogend
float fogRGBA[4]; // fog rgba
int shadowSize; // size of shadow map texture
int offWidth; // width of offscreen buffer
int offHeight; // height of offscreen buffer
int offSamples; // number of offscreen buffer multisamples
// parameters specified at creation
int fontScale; // font scale
int auxWidth[mjNAUX]; // auxiliary buffer width
int auxHeight[mjNAUX]; // auxiliary buffer height
int auxSamples[mjNAUX]; // auxiliary buffer multisamples
// offscreen rendering objects
unsigned int offFBO; // offscreen framebuffer object
unsigned int offFBO_r; // offscreen framebuffer for resolving multisamples
unsigned int offColor; // offscreen color buffer
unsigned int offColor_r; // offscreen color buffer for resolving multisamples
unsigned int offDepthStencil; // offscreen depth and stencil buffer
unsigned int offDepthStencil_r; // offscreen depth and stencil buffer for resolving multisamples
// shadow rendering objects
unsigned int shadowFBO; // shadow map framebuffer object
unsigned int shadowTex; // shadow map texture
// auxiliary buffers
unsigned int auxFBO[mjNAUX]; // auxiliary framebuffer object
unsigned int auxFBO_r[mjNAUX]; // auxiliary framebuffer object for resolving
unsigned int auxColor[mjNAUX]; // auxiliary color buffer
unsigned int auxColor_r[mjNAUX];// auxiliary color buffer for resolving
// texture objects and info
int ntexture; // number of allocated textures
int textureType[100]; // type of texture (mjtTexture) (ntexture)
unsigned int texture[100]; // texture names
// displaylist starting positions
unsigned int basePlane; // all planes from model
unsigned int baseMesh; // all meshes from model
unsigned int baseHField; // all hfields from model
unsigned int baseBuiltin; // all buildin geoms, with quality from model
unsigned int baseFontNormal; // normal font
unsigned int baseFontShadow; // shadow font
unsigned int baseFontBig; // big font
// displaylist ranges
int rangePlane; // all planes from model
int rangeMesh; // all meshes from model
int rangeHField; // all hfields from model
int rangeBuiltin; // all builtin geoms, with quality from model
int rangeFont; // all characters in font
// skin VBOs
int nskin; // number of skins
unsigned int* skinvertVBO; // skin vertex position VBOs (nskin)
unsigned int* skinnormalVBO; // skin vertex normal VBOs (nskin)
unsigned int* skintexcoordVBO; // skin vertex texture coordinate VBOs (nskin)
unsigned int* skinfaceVBO; // skin face index VBOs (nskin)
// character info
int charWidth[127]; // character widths: normal and shadow
int charWidthBig[127]; // chacarter widths: big
int charHeight; // character heights: normal and shadow
int charHeightBig; // character heights: big
// capabilities
int glInitialized; // is OpenGL initialized
int windowAvailable; // is default/window framebuffer available
int windowSamples; // number of samples for default/window framebuffer
int windowStereo; // is stereo available for default/window framebuffer
int windowDoublebuffer; // is default/window framebuffer double buffered
// framebuffer
int currentBuffer; // currently active framebuffer: mjFB_WINDOW or mjFB_OFFSCREEN
// pixel output format
int readPixelFormat; // default color pixel format for mjr_readPixels
// depth output format
int readDepthMap; // depth mapping: mjDEPTH_ZERONEAR or mjDEPTH_ZEROFAR
};
typedef struct mjrContext_ mjrContext;
User Interface#
For a high-level description of the UI framework, see User Interface.
The names of these struct types are prefixed with mjui, except for the main mjUI struct itself.
mjuiState#
This C struct represents the global state of the window, keyboard and mouse, input event descriptors, and all window
rectangles (including the visible UI rectangles). There is only one mjuiState per application, even if there are
multiple UIs. This struct would normally be defined as a global variable.
struct mjuiState_ { // mouse and keyboard state
// constants set by user
int nrect; // number of rectangles used
mjrRect rect[mjMAXUIRECT]; // rectangles (index 0: entire window)
void* userdata; // pointer to user data (for callbacks)
// event type
int type; // (type mjtEvent)
// mouse buttons
int left; // is left button down
int right; // is right button down
int middle; // is middle button down
int doubleclick; // is last press a double click
int button; // which button was pressed (mjtButton)
double buttontime; // time of last button press
// mouse position
double x; // x position
double y; // y position
double dx; // x displacement
double dy; // y displacement
double sx; // x scroll
double sy; // y scroll
// keyboard
int control; // is control down
int shift; // is shift down
int alt; // is alt down
int key; // which key was pressed
double keytime; // time of last key press
// rectangle ownership and dragging
int mouserect; // which rectangle contains mouse
int dragrect; // which rectangle is dragged with mouse
int dragbutton; // which button started drag (mjtButton)
// files dropping (only valid when type == mjEVENT_FILESDROP)
int dropcount; // number of files dropped
const char** droppaths; // paths to files dropped
};
typedef struct mjuiState_ mjuiState;
mjuiThemeSpacing#
This structure defines the spacing of UI items in the theme.
struct mjuiThemeSpacing_ { // UI visualization theme spacing
int total; // total width
int scroll; // scrollbar width
int label; // label width
int section; // section gap
int itemside; // item side gap
int itemmid; // item middle gap
int itemver; // item vertical gap
int texthor; // text horizontal gap
int textver; // text vertical gap
int linescroll; // number of pixels to scroll
int samples; // number of multisamples
};
typedef struct mjuiThemeSpacing_ mjuiThemeSpacing;
mjuiThemeColor#
This structure defines the colors of UI items in the theme.
struct mjuiThemeColor_ { // UI visualization theme color
float master[3]; // master background
float thumb[3]; // scrollbar thumb
float secttitle[3]; // section title
float sectfont[3]; // section font
float sectsymbol[3]; // section symbol
float sectpane[3]; // section pane
float shortcut[3]; // shortcut background
float fontactive[3]; // font active
float fontinactive[3]; // font inactive
float decorinactive[3]; // decor inactive
float decorinactive2[3]; // inactive slider color 2
float button[3]; // button
float check[3]; // check
float radio[3]; // radio
float select[3]; // select
float select2[3]; // select pane
float slider[3]; // slider
float slider2[3]; // slider color 2
float edit[3]; // edit
float edit2[3]; // edit invalid
float cursor[3]; // edit cursor
};
typedef struct mjuiThemeColor_ mjuiThemeColor;
mjuiItem#
This structure defines one UI item.
struct mjuiItemSingle_ { // check and button-related
int modifier; // 0: none, 1: control, 2: shift; 4: alt
int shortcut; // shortcut key; 0: undefined
};
struct mjuiItemMulti_ { // static, radio and select-related
int nelem; // number of elements in group
char name[mjMAXUIMULTI][mjMAXUINAME]; // element names
};
struct mjuiItemSlider_ { // slider-related
double range[2]; // slider range
double divisions; // number of range divisions
};
struct mjuiItemEdit_ { // edit-related
int nelem; // number of elements in list
double range[mjMAXUIEDIT][2]; // element range (min>=max: ignore)
};
struct mjuiItem_ { // UI item
// common properties
int type; // type (mjtItem)
char name[mjMAXUINAME]; // name
int state; // 0: disable, 1: enable, 2+: use predicate
void *pdata; // data pointer (type-specific)
int sectionid; // id of section containing item
int itemid; // id of item within section
// type-specific properties
union {
struct mjuiItemSingle_ single; // check and button
struct mjuiItemMulti_ multi; // static, radio and select
struct mjuiItemSlider_ slider; // slider
struct mjuiItemEdit_ edit; // edit
};
// internal
mjrRect rect; // rectangle occupied by item
};
typedef struct mjuiItem_ mjuiItem;
mjuiSection#
This structure defines one section of the UI.
struct mjuiSection_ { // UI section
// properties
char name[mjMAXUINAME]; // name
int state; // 0: closed, 1: open
int modifier; // 0: none, 1: control, 2: shift; 4: alt
int shortcut; // shortcut key; 0: undefined
int nitem; // number of items in use
mjuiItem item[mjMAXUIITEM]; // preallocated array of items
// internal
mjrRect rtitle; // rectangle occupied by title
mjrRect rcontent; // rectangle occupied by content
};
typedef struct mjuiSection_ mjuiSection;
mjuiDef#
This structure defines one entry in the definition table used for simplified UI construction. It contains everything needed to define one UI item. Some translation is performed by the helper functions, so that multiple mjuiDefs can be defined as a static table.
struct mjuiDef_ { // table passed to mjui_add()
int type; // type (mjtItem); -1: section
char name[mjMAXUINAME]; // name
int state; // state
void* pdata; // pointer to data
char other[mjMAXUITEXT]; // string with type-specific properties
};
typedef struct mjuiDef_ mjuiDef;
mjUI#
This C struct represents an entire UI. The same application could have multiple UIs, for example on the left and the right of the window. This would normally be defined as a global variable. As explained earlier, it contains static allocation for a maximum number of supported UI sections (mjuiSection) each with a maximum number of supported items (mjuiItem). It also contains the color and spacing themes, enable/disable callback, virtual window descriptor, text edit state, mouse focus. Some of these fields are set only once when the UI is initialized, others change at runtime.
struct mjUI_ { // entire UI
// constants set by user
mjuiThemeSpacing spacing; // UI theme spacing
mjuiThemeColor color; // UI theme color
mjfItemEnable predicate; // callback to set item state programmatically
void* userdata; // pointer to user data (passed to predicate)
int rectid; // index of this ui rectangle in mjuiState
int auxid; // aux buffer index of this ui
int radiocol; // number of radio columns (0 defaults to 2)
// UI sizes (framebuffer units)
int width; // width
int height; // current heigth
int maxheight; // height when all sections open
int scroll; // scroll from top of UI
// mouse focus
int mousesect; // 0: none, -1: scroll, otherwise 1+section
int mouseitem; // item within section
int mousehelp; // help button down: print shortcuts
// keyboard focus and edit
int editsect; // 0: none, otherwise 1+section
int edititem; // item within section
int editcursor; // cursor position
int editscroll; // horizontal scroll
char edittext[mjMAXUITEXT]; // current text
mjuiItem* editchanged; // pointer to changed edit in last mjui_event
// sections
int nsect; // number of sections in use
mjuiSection sect[mjMAXUISECT]; // preallocated array of sections
};
typedef struct mjUI_ mjUI;
Plugins#
The names of these struct types are prefixed with mjp. See Engine plugins for more details.
mjpPlugin#
This structure contains the definition of a single engine plugin. It mostly contains a set of callbacks, which are triggered by the compiler and the engine during various phases of the computation pipeline.
struct mjpPlugin_ {
const char* name; // globally unique name identifying the plugin
int nattribute; // number of configuration attributes
const char* const* attributes; // name of configuration attributes
int capabilityflags; // plugin capabilities: bitfield of mjtPluginCapabilityBit
int needstage; // sensor computation stage (mjtStage)
// number of mjtNums needed to store the state of a plugin instance (required)
int (*nstate)(const mjModel* m, int instance);
// dimension of the specified sensor's output (required only for sensor plugins)
int (*nsensordata)(const mjModel* m, int instance, int sensor_id);
// called when a new mjData is being created (required), returns 0 on success or -1 on failure
int (*init)(const mjModel* m, mjData* d, int instance);
// called when an mjData is being freed (optional)
void (*destroy)(mjData* d, int instance);
// called when an mjData is being copied (optional)
void (*copy)(mjData* dest, const mjModel* m, const mjData* src, int instance);
// called when an mjData is being reset (required)
void (*reset)(const mjModel* m, double* plugin_state, void* plugin_data, int instance);
// called when the plugin needs to update its outputs (required)
void (*compute)(const mjModel* m, mjData* d, int instance, int capability_bit);
// called when time integration occurs (optional)
void (*advance)(const mjModel* m, mjData* d, int instance);
// called by mjv_updateScene (optional)
void (*visualize)(const mjModel*m, mjData* d, const mjvOption* opt, mjvScene* scn, int instance);
// methods specific to actuators (optional)
// dimension of the actuator state for the plugin (excluding state from actuator's dyntype)
int (*actuator_actdim)(const mjModel*m, int instance, int actuator_id);
// updates the actuator plugin's entries in act_dot
// called after native act_dot is computed and before the compute callback
void (*actuator_act_dot)(const mjModel* m, mjData* d, int instance);
// methods specific to signed distance fields (optional)
// signed distance from the surface
mjtNum (*sdf_distance)(const mjtNum point[3], const mjData* d, int instance);
// gradient of distance with respect to local coordinates
void (*sdf_gradient)(mjtNum gradient[3], const mjtNum point[3], const mjData* d, int instance);
// called during compilation for marching cubes
mjtNum (*sdf_staticdistance)(const mjtNum point[3], const mjtNum* attributes);
// convert attributes and provide defaults if not present
void (*sdf_attribute)(mjtNum attribute[], const char* name[], const char* value[]);
// bounding box of implicit surface
void (*sdf_aabb)(mjtNum aabb[6], const mjtNum* attributes);
};
typedef struct mjpPlugin_ mjpPlugin;
mjpResourceProvider#
This data structure contains the definition of a resource provider. It contains a set of callbacks used for opening and reading resources.
struct mjpResourceProvider {
const char* prefix; // prefix for match against a resource name
mjfOpenResource open; // opening callback
mjfReadResource read; // reading callback
mjfCloseResource close; // closing callback
mjfGetResourceDir getdir; // get directory callback (optional)
mjfResourceModified modified; // resource modified callback (optional)
void* data; // opaque data pointer (resource invariant)
};
typedef struct mjpResourceProvider mjpResourceProvider;
Function types#
MuJoCo callbacks have corresponding function types. They are defined in mjdata.h and in mjui.h. The actual callback functions are documented in the globals page.
Physics Callbacks#
These function types are used by physics callbacks.
mjfGeneric#
typedef void (*mjfGeneric)(const mjModel* m, mjData* d);
This is the function type of the callbacks mjcb_passive and mjcb_control.
mjfConFilt#
typedef int (*mjfConFilt)(const mjModel* m, mjData* d, int geom1, int geom2);
This is the function type of the callback mjcb_contactfilter. The return value is 1: discard, 0: proceed with collision check.
mjfSensor#
typedef void (*mjfSensor)(const mjModel* m, mjData* d, int stage);
This is the function type of the callback mjcb_sensor.
mjfTime#
typedef mjtNum (*mjfTime)(void);
This is the function type of the callback mjcb_time.
mjfAct#
typedef mjtNum (*mjfAct)(const mjModel* m, const mjData* d, int id);
This is the function type of the callbacks mjcb_act_dyn, mjcb_act_gain and mjcb_act_bias.
mjfCollision#
typedef int (*mjfCollision)(const mjModel* m, const mjData* d,
mjContact* con, int g1, int g2, mjtNum margin);
This is the function type of the callbacks in the collision table mjCOLLISIONFUNC.
UI Callbacks#
These function types are used by the UI framework.
mjfItemEnable#
typedef int (*mjfItemEnable)(int category, void* data);
This is the function type of the predicate function used by the UI framework to determine if each item is enabled or disabled.
Resource Provider Callbacks#
These callbacks are used by resource providers.
mjfOpenResource#
typedef int (*mjfOpenResource)(mjResource* resource);
This callback is for opeing a resource; returns zero on failure.
mjfReadResource#
typedef int (*mjfReadResource)(mjResource* resource, const void** buffer);
This callback is for reading a resource. Returns number of bytes stored in buffer and returns -1 on error.
mjfCloseResource#
typedef void (*mjfCloseResource)(mjResource* resource);
This callback is for closing a resource, and is responsible for freeing any allocated memory.
mjfGetResourceDir#
typedef void (*mjfGetResourceDir)(mjResource* resource, const char** dir, int* ndir);
This callback is for returning the directory of a resource, by setting dir to the directory string with ndir being size of directory string.
mjfResourceModified#
typedef int (*mjfResourceModified)(const mjResource* resource);
This callback is for checking if a resource was modified since it was last read. Returns positive value if the resource was modified since last open, 0 if resource was not modified, and negative value if inconclusive.
Notes#
This section contains miscellaneous notes regarding data-structure conventions in MuJoCo struct types.
c-frame variables#
mjData contains two arrays with the c prefix, which are used for internal calculations: cdof and
cinert, both computed by mj_comPos. The c prefix means that quantities are with respect to the “c-frame”,
a frame at the center-of-mass of the local kinematic subtree (mjData.subtree_com), oriented like the world frame.
This choice increases the precision of kinematic computations for mechanisms that are distant from the global origin.
cdof:These 6D motion vectors (3 rotation, 3 translation) describe the instantaneous axis of a degree-of-freedom and are used by all Jacobian functions. The minimal computation required for analytic Jacobians is mj_kinematics followed by mj_comPos.
cinert:These 10-vectors describe the inertial properties of a body in the c-frame and are used by the Composite Rigid Body algorithm (mj_crb). The 10 numbers are packed arrays of lengths (6, 3, 1) with semantics:
cinert[0-5]: Upper triangle of the body’s inertia matrix.cinert[6-8]: Body mass multiplied by the body CoM’s offset from the c-frame origin.cinert[9]: Body mass.
Convex hulls#
The convex hull descriptors are stored in mjModel:
int* mesh_graphadr; // graph data address; -1: no graph (nmesh x 1)
int* mesh_graph; // convex graph data (nmeshgraph x 1)
If mesh N has a convex hull stored in mjModel (which is optional), then m->mesh_graphadr[N] is the offset
of mesh N’s convex hull data in m->mesh_graph. The convex hull data for each mesh is a record with the following
format:
int numvert;
int numface;
int vert_edgeadr[numvert];
int vert_globalid[numvert];
int edge_localid[numvert+3*numface];
int face_globalid[3*numface];
Note that the convex hull contains a subset of the vertices of the full mesh. We use the nomenclature globalid to
refer to vertex indices in the full mesh, and localid to refer to vertex indices in the convex hull. The meaning of
the fields is as follows:
numvertNumber of vertices in the convex hull.
numfaceNumber of faces in the convex hull.
vert_edgeadr[numvert]For each vertex in the convex hull, this is the offset of the edge record for that vertex in edge_localid.
vert_globalid[numvert]For each vertex in the convex hull, this is the corresponding vertex index in the full mesh
edge_localid[numvert+3*numface]This contains a sequence of edge records, one for each vertex in the convex hull. Each edge record is an array of vertex indices (in localid format) terminated with -1. For example, say the record for vertex 7 is: 3, 4, 5, 9, -1. This means that vertex 7 belongs to 4 edges, and the other ends of these edges are vertices 3, 4, 5, 9. In this way every edge is represented twice, in the edge records of its two vertices. Note that for a closed triangular mesh (such as the convex hulls used here), the number of edges is
3*numface/2. Thus when each edge is represented twice, we have3*numface edges. And since we are using the separator -1 at the end of each edge record (one separator per vertex), the length ofedge_localidisnumvert+3*numface.face_globalid[3*numface]For each face of the convex hull, this contains the indices of the three vertices in the full mesh