Mujoco_WASM/src/user/user_objects.h

// Copyright 2021 DeepMind Technologies Limited
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef MUJOCO_SRC_USER_USER_OBJECTS_H_
#define MUJOCO_SRC_USER_USER_OBJECTS_H_

#include <map>
#include <string>
#include <vector>

#include "lodepng.h"
#include <mujoco/mjmodel.h>

// forward declarations of all mjC/X classes
class mjCError;
class mjCAlternative;
class mjCBase;
class mjCBody;
class mjCJoint;
class mjCGeom;
class mjCSite;
class mjCCamera;
class mjCLight;
class mjCMesh;
class mjCSkin;
class mjCTexture;
class mjCMaterial;
class mjCPair;
class mjCBodyPair;
class mjCEquality;
class mjCTendon;
class mjCWrap;
class mjCActuator;
class mjCSensor;
class mjCNumeric;
class mjCText;
class mjCTuple;
class mjCDef;
class mjCMesh;                      // defined in user_mesh
class mjCModel;                     // defined in user_model
class mjXWriter;                    // defined in xml_native
class mjXURDF;                      // defined in xml_urdf


//------------------------- helper classes and constants -------------------------------------------

// number of positive size parameters for each geom type
const int mjGEOMINFO[mjNGEOMTYPES] = {3, 0, 1, 2, 3, 2, 3, 0};


// builtin type for procedural textures
typedef enum _mjtBuiltin {
  mjBUILTIN_NONE = 0,             // no builtin
  mjBUILTIN_GRADIENT,             // circular gradient: rgb1->rgb2->rgb3
  mjBUILTIN_CHECKER,              // checker pattern: rgb1, rgb2
  mjBUILTIN_FLAT                  // 2d: rgb1; cube: rgb1-up, rgb2-side, rgb3-down
} mjtBuiltin;


// mark type for procedural textures
typedef enum _mjtMark {
  mjMARK_NONE = 0,                // no mark
  mjMARK_EDGE,                    // paint edges
  mjMARK_CROSS,                   // paint cross
  mjMARK_RANDOM                   // paint random dots
} mjtMark;


// type of mesh
typedef enum _mjtMeshType {
  mjVOLUME_MESH,
  mjSHELL_MESH,
} mjtMeshType;


// error information
class [[nodiscard]] mjCError {
 public:
  mjCError(const mjCBase* obj = 0,
           const char* msg = 0,
           const char* str = 0,
           int pos1 = 0,
           int pos2 = 0);

  char message[500];              // error message
  bool warning;                   // is this a warning instead of error
};


// alternative specifications of frame orientation
class mjCAlternative {
 public:
  mjCAlternative();                               // constuctor
  const char* Set(double* quat, double* inertia,  // set frame quat and diag. inertia
                  bool degree,                    //  angle format: degree/radian
                  const char* sequence);          //  euler sequence format: "xyz"

  double axisangle[4];            // rotation axis and angle
  double xyaxes[6];               // x and y axes
  double zaxis[3];                // z axis (use minimal rotation)
  double euler[3];                // euler rotations
  double fullinertia[6];          // non-axis-aligned inertia matrix
};



//------------------------- class mjCBase ----------------------------------------------------------
// Generic functionality for all derived classes

class mjCPlugin;
class mjCBase {
  friend class mjCDef;

 public:
  std::string name;               // object name
  std::string classname;          // defaults class name
  int id;                         // object id
  int xmlpos[2];                  // row and column in xml file
  mjCDef* def;                    // defaults class used to init this object
  mjCModel* model;                // pointer to model that created object

  // plugin support
  bool is_plugin;
  std::string plugin_name;
  std::string plugin_instance_name;
  mjCPlugin* plugin_instance;

 protected:
  mjCBase();                      // constructor
};



//------------------------- class mjCBody -----------------------------------------------
// Describes a rigid body

class mjCBody : public mjCBase {
  friend class mjCJoint;
  friend class mjCGeom;
  friend class mjCSite;
  friend class mjCCamera;
  friend class mjCLight;
  friend class mjCEquality;
  friend class mjCPair;
  friend class mjCModel;
  friend class mjXReader;
  friend class mjXWriter;
  friend class mjXURDF;

 public:
  // API for adding objects to body
  mjCBody*    AddBody(mjCDef* = 0);
  mjCJoint*   AddJoint(mjCDef* = 0, bool isfree = false);
  mjCGeom*    AddGeom(mjCDef* = 0);
  mjCSite*    AddSite(mjCDef* = 0);
  mjCCamera*  AddCamera(mjCDef* = 0);
  mjCLight*   AddLight(mjCDef* = 0);

  // API for accessing objects
  int NumObjects(mjtObj type);
  mjCBase* GetObject(mjtObj type, int id);
  mjCBase* FindObject(mjtObj type, std::string name, bool recursive = true);

  // setup child local frame, take into account change
  void MakeLocal(double* locpos, double* locquat, const double* pos, const double* quat);

  // set explicitinertial to true
  void MakeInertialExplicit();

  // variables set by user or 'Compile'
  bool mocap;                     // is this a mocap body
  double pos[3];                  // frame position
  double quat[4];                 // frame orientation
  double ipos[3];                 // inertial frame position
  double iquat[4];                // inertial frame orientation
  double mass;                    // mass
  double inertia[3];              // diagonal inertia (in i-frame)
  std::vector<double> userdata;   // user data
  mjCAlternative alt;             // alternative orientation specification
  mjCAlternative ialt;            // alternative for inertial frame

  // variables computed by 'Compile' and 'AddXXX'
 private:
  mjCBody(mjCModel*);                 // constructor
  ~mjCBody();                         // destructor
  void Compile(void);                 // compiler

  void GeomFrame(void);               // get inertial info from geoms

  double locpos[3];               // position relative to parent
  double locquat[4];              // orientation relative to parent
  double locipos[3];              // inertial position frame, rel. to local frame
  double lociquat[4];             // inertial frame orientation
  int parentid;                   // parent index in global array
  int weldid;                     // top index of body we are welded to
  int dofnum;                     // number of motion dofs for body
  int mocapid;                    // mocap id, -1: not mocap
  bool explicitinertial;          // whether to save the body with an explicit inertial clause

  int lastdof;                    // id of last dof (used by compiler)

  // objects allocated by Add functions
  std::vector<mjCBody*>    bodies;     // child bodies
  std::vector<mjCGeom*>    geoms;      // geoms attached to this body
  std::vector<mjCJoint*>   joints;     // joints allowing motion relative to parent
  std::vector<mjCSite*>    sites;      // sites attached to this body
  std::vector<mjCCamera*>  cameras;    // cameras attached to this body
  std::vector<mjCLight*>   lights;     // lights attached to this body
};



//------------------------- class mjCJoint ---------------------------------------------------------
// Describes a motion degree of freedom of a body relative to its parent

class mjCJoint : public mjCBase {
  friend class mjCDef;
  friend class mjCEquality;
  friend class mjCBody;
  friend class mjCModel;
  friend class mjXWriter;
  friend class mjXURDF;

 public:
  // variables set by user: joint properties
  mjtJoint type;                  // type of Joint
  int group;                      // used for rendering
  int limited;                    // does joint have limits: 0 false, 1 true, 2 auto
  double pos[3];                  // anchor position
  double axis[3];                 // joint axis
  double stiffness;               // stiffness coefficient
  double springdamper[2];         // timeconst, dampratio
  double range[2];                // joint limits
  mjtNum solref_limit[mjNREF];    // solver reference: joint limits
  mjtNum solimp_limit[mjNIMP];    // solver impedance: joint limits
  mjtNum solref_friction[mjNREF]; // solver reference: dof friction
  mjtNum solimp_friction[mjNIMP]; // solver impedance: dof friction
  double margin;                  // margin value for joint limit detection
  double ref;                     // value at reference configuration: qpos0
  double springref;               // spring reference value: qpos_spring
  std::vector<double> userdata;   // user data

  // variables set by user: dof properties
  double armature;                // armature inertia (mass for slider)
  double damping;                 // damping coefficient
  double frictionloss;            // friction loss

  double urdfeffort;              // store effort field from urdf

 private:
  mjCJoint(mjCModel* = 0, mjCDef* = 0);// constructor
  int Compile(void);                  // compiler; return dofnum

  mjCBody* body;                  // joint's body
  double locpos[3];               // anchor position in child or parent
  double locaxis[3];              // joint axis in child or parent
};



//------------------------- class mjCGeom ----------------------------------------------------------
// Describes a geometric shape belonging to a body

class mjCGeom : public mjCBase {
  friend class mjCDef;
  friend class mjCMesh;
  friend class mjCPair;
  friend class mjCBody;
  friend class mjCModel;
  friend class mjXWriter;
  friend class mjXURDF;

 public:
  double GetVolume(void);             // compute geom volume
  void SetInertia(void);              // compute and set geom inertia

  // Compute all coefs modeling the interaction with the surrounding fluid.
  void SetFluidCoefs(void);
  // Compute the kappa coefs of the added inertia due to the surrounding fluid.
  double GetAddedMassKappa(double dx, double dy, double dz);

  // variables set by user and copied into mjModel
  mjtGeom type;                   // geom type
  int contype;                    // contact type
  int conaffinity;                // contact affinity
  int condim;                     // contact dimensionality
  int group;                      // used for rendering
  int priority;                   // contact priority
  double size[3];                 // geom-specific size parameters
  double friction[3];             // one-sided friction coefficients: slide, roll, spin
  double solmix;                  // solver mixing for contact pairs
  mjtNum solref[mjNREF];          // solver reference
  mjtNum solimp[mjNIMP];          // solver impedance
  double margin;                  // margin for contact detection
  double gap;                     // include in solver if dist<margin-gap
  mjtNum fluid_switch;            // whether ellipsoid-fluid model is active
  mjtNum fluid_coefs[5];          // tunable ellipsoid-fluid interaction coefs
  mjtNum fluid[mjNFLUID];         // compile-time fluid-interaction parameters
  std::string hfield;             // hfield attached to geom
  std::string mesh;               // mesh attached to geom
  double fitscale;                // scale mesh uniformly
  std::string material;           // name of material used for rendering
  std::vector<double> userdata;   // user data
  float rgba[4];                  // rgba when material is omitted
  mjtMeshType typeinertia;        // selects between surface and volume inertia
  bool inferinertia;              // true if inertia has to be computed from geom

  // variables set by user and used during compilation
  double _mass;                   // used to compute density
  double density;                 // used to compute mass and inertia (from volume)
  double fromto[6];               // alternative for capsule, cylinder, box, ellipsoid
  mjCAlternative alt;             // alternative orientation specifications

  // variables set by user or 'Compile1'
  double pos[3];                  // position
  double quat[4];                 // orientation

 private:
  mjCGeom(mjCModel* = 0, mjCDef* = 0);// constructor
  void Compile(void);                 // compiler
  double GetRBound(void);             // compute bounding sphere radius

  int matid;                      // id of geom's material
  int meshid;                     // id of geom's mesh (-1: none)
  int hfieldid;                   // id of geom's hfield (-1: none)
  double mass;                    // mass
  double inertia[3];              // local diagonal inertia
  double locpos[3];               // local position
  double locquat[4];              // local orientation
  mjCBody* body;                  // geom's body
};



//------------------------- class mjCSite ----------------------------------------------------------
// Describes a site on a body

class mjCSite : public mjCBase {
  friend class mjCDef;
  friend class mjCBody;
  friend class mjCModel;
  friend class mjXWriter;
  friend class mjXURDF;

 public:
  // variables set by user
  mjtGeom type;                   // geom type for rendering
  int group;                      // group id, used for visualization
  double size[3];                 // geom size for rendering
  double pos[3];                  // position
  double quat[4];                 // orientation
  std::string material;           // name of material for rendering
  std::vector<double> userdata;   // user data
  float rgba[4];                  // rgba when material is omitted
  double fromto[6];               // alternative for capsule, cylinder, box, ellipsoid
  mjCAlternative alt;             // alternative orientation specification

  // variables computed by 'compile' and 'mjCBody::addSite'
 private:
  mjCSite(mjCModel* = 0, mjCDef* = 0);    // constructor
  void Compile(void);                     // compiler

  mjCBody* body;                  // site's body
  double locpos[3];               // local position
  double locquat[4];              // local orientation
  int matid;                      // material id for rendering
};



//------------------------- class mjCCamera --------------------------------------------------------
// Describes a camera, attached to a body

class mjCCamera : public mjCBase {
  friend class mjCDef;
  friend class mjCBody;
  friend class mjCModel;
  friend class mjXWriter;

 public:
  // variables set by user
  mjtCamLight mode;               // tracking mode
  std::string targetbody;         // target body for orientation
  double fovy;                    // y-field of view
  double ipd;                     // inter-pupilary distance
  double pos[3];                  // position
  double quat[4];                 // orientation
  std::vector<double> userdata;   // user data
  mjCAlternative alt;             // alternative orientation specification

 private:
  mjCCamera(mjCModel* = 0, mjCDef* = 0);  // constructor
  void Compile(void);                     // compiler

  mjCBody* body;                  // camera's body
  double locpos[3];               // local position
  double locquat[4];              // local orientation
  int targetbodyid;               // id of target body; -1: none
};



//------------------------- class mjCLight ---------------------------------------------------------
// Describes a light, attached to a body

class mjCLight : public mjCBase {
  friend class mjCDef;
  friend class mjCBody;
  friend class mjCModel;
  friend class mjXWriter;

 public:
  // variables set by user
  mjtCamLight mode;               // tracking mode
  std::string targetbody;         // target body for orientation
  bool directional;               // directional light
  bool castshadow;                // does light cast shadows
  bool active;                    // is light active
  double pos[3];                  // position
  double dir[3];                  // direction
  float attenuation[3];           // OpenGL attenuation (quadratic model)
  float cutoff;                   // OpenGL cutoff
  float exponent;                 // OpenGL exponent
  float ambient[3];               // ambient color
  float diffuse[3];               // diffuse color
  float specular[3];              // specular color

 private:
  mjCLight(mjCModel* = 0, mjCDef* = 0);   // constructor
  void Compile(void);                     // compiler

  mjCBody* body;                  // light's body
  double locpos[3];               // local position
  double locdir[3];               // local direction
  int targetbodyid;               // id of target body; -1: none
};



//------------------------- class mjCMesh ----------------------------------------------------------
// Describes a mesh

class mjCMesh: public mjCBase {
  friend class mjCDef;
  friend class mjCGeom;
  friend class mjCBody;
  friend class mjCSkin;
  friend class mjCModel;
  friend class mjXWriter;

 public:
  double* GetPosPtr(mjtMeshType type);              // get position
  double* GetQuatPtr(mjtMeshType type);             // get orientation
  double* GetInertiaBoxPtr(mjtMeshType type);       // get inertia box
  double& GetVolumeRef(mjtMeshType type);           // get volume
  void FitGeom(mjCGeom* geom, double* meshpos);   // approximate mesh with simple geom

  std::string file;                   // mesh file
  double refpos[3];                   // reference position (translate)
  double refquat[4];                  // reference orientation (rotate)
  double scale[3];                    // rescale mesh
  bool smoothnormal;                  // do not exclude large-angle faces from normals

  std::vector<float> uservert;                   // user vertex data
  std::vector<float> usernormal;                 // user normal data
  std::vector<float> usertexcoord;               // user texcoord data
  std::vector<int> userface;                     // user face data
  std::vector< std::pair<int, int> > useredge;   // user half-edge data

 private:
  mjCMesh(mjCModel* = 0, mjCDef* = 0);        // constructor
  ~mjCMesh();                                 // destructor
  void Compile(const mjVFS* vfs);             // compiler
  void LoadOBJ(const mjVFS* vfs);             // load mesh in wavefront OBJ format
  void LoadSTL(const mjVFS* vfs);             // load mesh in STL BIN format
  void LoadMSH(const mjVFS* vfs);             // load mesh in MSH BIN format
  void MakeGraph(void);                       // make graph of convex hull
  void CopyGraph(void);                       // copy graph into face data
  void MakeNormal(void);                      // compute vertex normals
  void Process();                             // apply transformations
  void RemoveRepeated(void);                  // remove repeated vertices
  void ComputeInertia(mjtMeshType type);      // compute inertia
  void CheckMesh(void);                       // check if the mesh is valid

  // mesh properties that indicate a well-formed mesh
  bool validorientation;              // false if mesh have inconsistent faces
  bool validarea;                     // false if the area is too small
  bool validvolume;                   // false if the volume is too small
  bool valideigenvalue;               // false if inertia eigenvalue is too small
  bool validinequality;               // false if inertia inequality is not satisfied
  bool processed;                     // false if the mesh has not been processed yet

  // mesh properties computed by Compile
  double pos_volume[3];               // CoM position
  double pos_surface[3];              // CoM position
  double quat_volume[4];              // inertia orientation
  double quat_surface[4];             // inertia orientation
  double boxsz_volume[3];             // half-sizes of equivalent inertia box (volume)
  double boxsz_surface[3];            // half-sizes of equivalent inertia box (surface)
  double aabb[3];                     // half-sizes of axis-aligned bounding box
  double volume;                      // volume of the mesh
  double surface;                     // surface of the mesh

  // mesh data to be copied into mjModel
  int nvert;                          // number of vertices
  int nface;                          // number of faces
  int szgraph;                        // size of graph data in ints
  float* vert;                        // vertex data (3*nvert), relative to (pos, quat)
  float* normal;                      // vertex normal data (3*nvert)
  float* texcoord;                    // vertex texcoord data (2*nvert, or NULL)
  int* face;                          // face vertex indices (3*nface)
  int* graph;                         // convex graph data

  bool needhull;                      // needs convex hull for collisions
};



//------------------------- class mjCSkin ----------------------------------------------------------
// Describes a skin

class mjCSkin: public mjCBase {
  friend class mjCModel;
  friend class mjXWriter;

 public:
  std::string file;                   // skin file
  std::string material;               // name of material used for rendering
  float rgba[4];                      // rgba when material is omitted
  float inflate;                      // inflate in normal direction
  int group;                          // group for visualization

  // mesh
  std::vector<float> vert;            // vertex positions
  std::vector<float> texcoord;        // texture coordinates
  std::vector<int> face;              // faces

  // skin
  std::vector<std::string> bodyname;  // body names
  std::vector<float> bindpos;         // bind pos
  std::vector<float> bindquat;        // bind quat
  std::vector<std::vector<int>> vertid;         // vertex ids
  std::vector<std::vector<float>> vertweight;   // vertex weights

 private:
  mjCSkin(mjCModel* = 0);                     // constructor
  ~mjCSkin();                                 // destructor
  void Compile(const mjVFS* vfs);             // compiler
  void LoadSKN(const mjVFS* vfs);             // load skin in SKN BIN format

  int matid;                          // material id
  std::vector<int> bodyid;            // body ids
};



//------------------------- class mjCHField --------------------------------------------------------
// Describes a height field

class mjCHField : public mjCBase {
  friend class mjCModel;
  friend class mjXWriter;

 public:
  std::string file;               // file: (nrow, ncol, [elevation data])
  double size[4];                 // hfield size (ignore referencing geom size)
  int nrow;                       // number of rows
  int ncol;                       // number of columns
  float* data;                    // elevation data, row-major format

 private:
  mjCHField(mjCModel* model);             // constructor
  ~mjCHField();                           // destructor
  void Compile(const mjVFS* vfs);         // compiler

  void LoadCustom(std::string filename, const mjVFS* vfs); // load from custom format
  void LoadPNG(std::string filename, const mjVFS* vfs);    // load from PNG format
};



//------------------------- class mjCTexture -------------------------------------------------------
// Describes a texture

class mjCTexture : public mjCBase {
  friend class mjCModel;
  friend class mjXReader;
  friend class mjXWriter;

 public:
  mjtTexture type;                // texture type

  // method 1: builtin
  mjtBuiltin builtin;             // builtin type
  mjtMark mark;                   // mark type
  double rgb1[3];                 // first color for builtin
  double rgb2[3];                 // second color for builtin
  double markrgb[3];              // mark color
  double random;                  // probability of random dots
  int height;                     // height in pixels (square for cube and skybox)
  int width;                      // width in pixels

  // method 2: single file
  std::string file;               // png file to load; use for all sides of cube
  int gridsize[2];                // size of grid for composite file; (1,1)-repeat
  char gridlayout[13];            // row-major: L,R,F,B,U,D for faces; . for unused

  // method 3: separate files
  std::string cubefiles[6];       // different file for each side of the cube

  // flip options
  bool hflip;                     // horizontal flip
  bool vflip;                     // vertical flip

 private:
  mjCTexture(mjCModel*);                  // constructor
  ~mjCTexture();                          // destructior
  void Compile(const mjVFS* vfs);         // compiler

  void Builtin2D(void);                   // make builtin 2D
  void BuiltinCube(void);                 // make builtin cube
  void Load2D(std::string filename, const mjVFS* vfs);         // load 2D from file
  void LoadCubeSingle(std::string filename, const mjVFS* vfs); // load cube from single file
  void LoadCubeSeparate(const mjVFS* vfs);                     // load cube from separate files

  void LoadFlip(std::string filename, const mjVFS* vfs,   // load and flip
                std::vector<unsigned char>& image,
                unsigned int& w, unsigned int& h);

  void LoadPNG(std::string filename, const mjVFS* vfs,
               std::vector<unsigned char>& image,
               unsigned int& w, unsigned int& h);
  void LoadCustom(std::string filename, const mjVFS* vfs,
                  std::vector<unsigned char>& image,
                  unsigned int& w, unsigned int& h);

  mjtByte* rgb;                   // rgb data
};



//------------------------- class mjCMaterial ------------------------------------------------------
// Describes a material for rendering

class mjCMaterial : public mjCBase {
  friend class mjCDef;
  friend class mjCModel;
  friend class mjXWriter;

 public:
  // variables set by user
  std::string texture;            // name of texture (empty: none)
  bool texuniform;                // make texture cube uniform
  float texrepeat[2];             // texture repetition for 2D mapping
  float emission;                 // emission
  float specular;                 // specular
  float shininess;                // shininess
  float reflectance;              // reflectance
  float rgba[4];                  // rgba

 private:
  mjCMaterial(mjCModel* = 0, mjCDef* = 0);// constructor
  void Compile(void);                     // compiler

  int texid;                      // id of material
};



//------------------------- class mjCPair ----------------------------------------------------------
// Predefined geom pair for collision detection

class mjCPair : public mjCBase {
  friend class mjCDef;
  friend class mjCBody;
  friend class mjCModel;

 public:
  // parameters set by user
  std::string geomname1;          // name of geom 1
  std::string geomname2;          // name of geom 2

  // optional parameters: computed from geoms if not set by user
  int condim;                     // contact dimensionality
  mjtNum solref[mjNREF];          // solver reference
  mjtNum solimp[mjNIMP];          // solver impedance
  double margin;                  // margin for contact detection
  double gap;                     // include in solver if dist<margin-gap
  double friction[5];             // full contact friction

  int GetSignature(void) {
    return signature;
  }

 private:
  mjCPair(mjCModel* = 0, mjCDef* = 0);// constructor
  void Compile(void);                 // compiler

  int geom1;                      // id of geom1
  int geom2;                      // id of geom2
  int signature;                  // (body1+1)<<16 + body2+1
};



//------------------------- class mjCBodyPair ------------------------------------------------------
// Body pair specification, use to exclude pairs

class mjCBodyPair : public mjCBase {
  friend class mjCBody;
  friend class mjCModel;

 public:
  // parameters set by user
  std::string bodyname1;          // name of geom 1
  std::string bodyname2;          // name of geom 2

  int GetSignature(void) {
    return signature;
  }

 private:
  mjCBodyPair(mjCModel*);             // constructor
  void Compile(void);                 // compiler

  int body1;                      // id of body1
  int body2;                      // id of body2
  int signature;                  // (body1+1)<<16 + body2+1
};



//------------------------- class mjCEquality ------------------------------------------------------
// Describes an equality constraint

class mjCEquality : public mjCBase {
  friend class mjCDef;
  friend class mjCBody;
  friend class mjCModel;
  friend class mjXWriter;

 public:
  // variables set by user
  mjtEq type;                     // constraint type
  std::string name1;              // name of object 1
  std::string name2;              // name of object 2
  bool active;                    // initial activation state
  mjtNum solref[mjNREF];          // solver reference
  mjtNum solimp[mjNIMP];          // solver impedance
  double data[mjNEQDATA];         // type-dependent data

 private:
  mjCEquality(mjCModel* = 0, mjCDef* = 0);  // constructor
  void Compile(void);                       // compiler

  int obj1id;                     // id of object 1
  int obj2id;                     // id of object 2
};



//------------------------- class mjCTendon --------------------------------------------------------
// Describes a tendon

class mjCTendon : public mjCBase {
  friend class mjCDef;
  friend class mjCModel;
  friend class mjXWriter;

 public:
  // API for adding wrapping objects
  void WrapSite(std::string name, int row=-1, int col=-1);                    // site
  void WrapGeom(std::string name, std::string side, int row=-1, int col=-1);  // geom
  void WrapJoint(std::string name, double coef, int row=-1, int col=-1);      // joint
  void WrapPulley(double divisor, int row=-1, int col=-1);                    // pulley

  // API for access to wrapping objects
  int NumWraps(void);                         // number of wraps
  mjCWrap* GetWrap(int);                      // pointer to wrap

  // variables set by user
  int group;                      // group for visualization
  std::string material;           // name of material for rendering
  int limited;                    // does tendon have limits: 0 false, 1 true, 2 auto
  double width;                   // width for rendering
  mjtNum solref_limit[mjNREF];    // solver reference: tendon limits
  mjtNum solimp_limit[mjNIMP];    // solver impedance: tendon limits
  mjtNum solref_friction[mjNREF]; // solver reference: tendon friction
  mjtNum solimp_friction[mjNIMP]; // solver impedance: tendon friction
  double range[2];                // length limits
  double margin;                  // margin value for tendon limit detection
  double stiffness;               // stiffness coefficient
  double damping;                 // damping coefficient
  double frictionloss;            // friction loss
  double springlength;            // spring length; -1: use qpos_spring
  std::vector<double> userdata;   // user data
  float rgba[4];                  // rgba when material is omitted

 private:
  mjCTendon(mjCModel* = 0, mjCDef* = 0);      // constructor
  ~mjCTendon();                               // destructor
  void Compile(void);                         // compiler

  int matid;                      // material id for rendering
  std::vector<mjCWrap*> path;     // wrapping objects
};



//------------------------- class mjCWrap ----------------------------------------------------------
// Describes a tendon wrap object

class mjCWrap : public mjCBase {
  friend class mjCTendon;
  friend class mjCModel;

 public:
  mjtWrap type;                   // wrap object type
  int objid;                      // wrap object id (in array corresponding to type)
  int sideid;                     // side site id; -1 if not applicable
  double prm;                     // parameter: divisor, coefficient
  std::string sidesite;           // name of side site

 private:
  mjCWrap(mjCModel*, mjCTendon*);     // constructor
  void Compile(void);                 // compiler

  mjCTendon* tendon;              // tendon owning this wrap
};



//------------------------- class mjCPlugin --------------------------------------------------------
// Describes an instance of a plugin

class mjCPlugin : public mjCBase {
  friend class mjCModel;
  friend class mjXWriter;

 public:
  int plugin_slot;   // global registered slot number of the plugin
  int nstate;        // state size for the plugin instance
  mjCBase* parent;   // parent object (only used when generating error message)
  std::map<std::string, std::string, std::less<>> config_attribs;  // raw config attributes from XML
  std::vector<char> flattened_attributes;  // config attributes flattened in plugin-declared order

 private:
  mjCPlugin(mjCModel*);            // constructor
  void Compile(void);              // compiler
};



//------------------------- class mjCActuator ------------------------------------------------------
// Describes an actuator

class mjCActuator : public mjCBase {
  friend class mjCDef;
  friend class mjCModel;
  friend class mjXWriter;

 public:
  // variables set by user or API
  int group;                      // group for visualization
  int ctrllimited;               // are control limits defined: 0 false, 1 true, 2 auto
  int forcelimited;              // are force limits defined: 0 false, 1 true, 2 auto
  int actlimited;                // are activation limits defined: 0 false, 1 true, 2 auto
  mjtDyn dyntype;                 // dynamics type
  mjtTrn trntype;                 // transmission type
  mjtGain gaintype;               // gain type
  mjtBias biastype;               // bias type
  double dynprm[mjNDYN];          // dynamics parameters
  double gainprm[mjNGAIN];        // gain parameters
  double biasprm[mjNGAIN];        // bias parameters
  double ctrlrange[2];            // control range
  double forcerange[2];           // force range
  double actrange[2];             // activation range
  double lengthrange[2];          // length range
  double gear[6];                 // length and transmitted force scaling
  double cranklength;             // crank length, for slider-crank only
  std::vector<double> userdata;   // user data
  std::string target;             // transmission target name
  std::string slidersite;         // site defining cylinder, for slider-crank only
  std::string refsite;            // reference site, for site transmission only

  // plugin support
  bool is_plugin;
  std::string plugin_name;
  std::string plugin_instance_name;
  mjCPlugin* plugin_instance;

 private:
  mjCActuator(mjCModel* = 0, mjCDef* = 0);// constructor
  void Compile(void);                     // compiler

  int trnid[2];                   // id of transmission target
};



//------------------------- class mjCSensor --------------------------------------------------------
// Describes a sensor

class mjCSensor : public mjCBase {
  friend class mjCDef;
  friend class mjCModel;
  friend class mjXWriter;

 public:
  // variables set by user or API
  mjtSensor type;                 // type of sensor
  mjtDataType datatype;           // data type for sensor measurement
  mjtStage needstage;             // compute stage needed to simulate sensor
  mjtObj objtype;                 // type of sensorized object
  std::string objname;            // name of sensorized object
  mjtObj reftype;
  std::string refname;
  int dim;                        // number of scalar outputs
  double cutoff;                  // cutoff for real and positive datatypes
  double noise;                   // noise stdev
  std::vector<double> userdata;   // user data

  // plugin support
  std::string plugin_name;
  std::string plugin_instance_name;
  mjCPlugin* plugin_instance;

 private:
  mjCSensor(mjCModel*);           // constructor
  void Compile(void);             // compiler

  int objid;                      // id of sensorized object
  int refid;                      // id of reference frame
};



//------------------------- class mjCNumeric -------------------------------------------------------
// Describes a custom data field

class mjCNumeric : public mjCBase {
  friend class mjCModel;

 public:
  // variables set by user
  std::vector<double> data;       // initialization data
  int size;                       // array size, can be bigger than data.size()

 private:
  mjCNumeric(mjCModel*);              // constructor
  ~mjCNumeric();                      // destructor
  void Compile(void);                 // compiler
};



//------------------------- class mjCText ----------------------------------------------------------
// Describes a custom text field

class mjCText : public mjCBase {
  friend class mjCModel;

 public:
  // variables set by user
  std::string data;               // string

 private:
  mjCText(mjCModel*);                 // constructor
  ~mjCText();                         // destructor
  void Compile(void);                 // compiler
};



//------------------------- class mjCTuple ---------------------------------------------------------
// Describes a custom tuple field

class mjCTuple : public mjCBase {
  friend class mjCModel;

 public:
  // variables set by user
  std::vector<mjtObj> objtype;       // object types
  std::vector<std::string> objname;  // object names
  std::vector<double> objprm;        // object parameters

 private:
  mjCTuple(mjCModel*);            // constructor
  ~mjCTuple();                    // destructor
  void Compile(void);             // compiler

  std::vector<int> objid;         // object ids
};



//------------------------- class mjCKey -----------------------------------------------------------
// Describes a keyframe

class mjCKey : public mjCBase {
  friend class mjCModel;
  friend class mjXWriter;

 public:
  double time;                    // time
  std::vector<double> qpos;       // qpos
  std::vector<double> qvel;       // qvel
  std::vector<double> act;        // act
  std::vector<double> mpos;       // mocap pos
  std::vector<double> mquat;      // mocap quat
  std::vector<double> ctrl;       // ctrl

 private:
  mjCKey(mjCModel*);              // constructor
  ~mjCKey();                      // destructor
  void Compile(const mjModel* m); // compiler
};



//------------------------- class mjCDef -----------------------------------------------------------
// Describes one set of defaults

class mjCDef {
 public:
  mjCDef(void);                           // constructor
  void Compile(const mjCModel* model);    // compiler

  // identifiers
  std::string name;               // class name
  int parentid;                   // id of parent class
  std::vector<int> childid;       // ids of child classes

  // default objects
  mjCJoint    joint;
  mjCGeom     geom;
  mjCSite     site;
  mjCCamera   camera;
  mjCLight    light;
  mjCMesh     mesh;
  mjCMaterial material;
  mjCPair     pair;
  mjCEquality equality;
  mjCTendon   tendon;
  mjCActuator actuator;
};

#endif  // MUJOCO_SRC_USER_USER_OBJECTS_H_