Add mjmJoint, mjmCamera, and mjmLight to C API.

PiperOrigin-RevId: 605596008
Change-Id: Ie53ac4b99f5336380039ab5eb9b2ca4a82768b28

src/user/user_api.cc

@@ -38,6 +38,14 @@ void mjm_deleteModel(void* modelspec) {
 
 
 
+// copy spec into private attributes
+MJAPI void mjm_finalize(mjElement object) {
+  mjCBase* baseC = reinterpret_cast<mjCBase*>(object);
+  baseC->CopyFromSpec();
+}
+
+
+
 // add child body to body, return child spec
 mjmBody* mjm_addBody(mjmBody* bodyspec, void* defspec) {
   mjCDef* def = static_cast<mjCDef*>(defspec);
@@ -58,20 +66,20 @@ mjmSite* mjm_addSite(mjmBody* bodyspec, void* defspec) {
 
 
 // add joint to body
-void* mjm_addJoint(mjmBody* bodyspec, void* defspec) {
+mjmJoint* mjm_addJoint(mjmBody* bodyspec, void* defspec) {
   mjCDef* def = static_cast<mjCDef*>(defspec);
   mjCBody* body = reinterpret_cast<mjCBody*>(bodyspec->element);
   mjCJoint* joint = body->AddJoint(def);
-  return joint;
+  return &joint->spec;
 }
 
 
 
 // add free joint to body
-void* mjm_addFreeJoint(mjmBody* bodyspec) {
+mjmJoint* mjm_addFreeJoint(mjmBody* bodyspec) {
   mjCBody* body = reinterpret_cast<mjCBody*>(bodyspec->element);
   mjCJoint* joint = body->AddFreeJoint();
-  return joint;
+  return &joint->spec;
 }
 
 
@@ -87,21 +95,21 @@ mjmGeom* mjm_addGeom(mjmBody* bodyspec, void* defspec) {
 
 
 // add camera to body
-void* mjm_addCamera(mjmBody* bodyspec, void* defspec) {
+mjmCamera* mjm_addCamera(mjmBody* bodyspec, void* defspec) {
   mjCDef* def = static_cast<mjCDef*>(defspec);
   mjCBody* body = reinterpret_cast<mjCBody*>(bodyspec->element);
   mjCCamera* camera = body->AddCamera(def);
-  return camera;
+  return &camera->spec;
 }
 
 
 
 // add light to body
-void* mjm_addLight(mjmBody* bodyspec, void* defspec) {
+mjmLight* mjm_addLight(mjmBody* bodyspec, void* defspec) {
   mjCDef* def = static_cast<mjCDef*>(defspec);
   mjCBody* body = reinterpret_cast<mjCBody*>(bodyspec->element);
   mjCLight* light = body->AddLight(def);
-  return light;
+  return &light->spec;
 }
 
 

src/user/user_api.h

@@ -76,6 +76,42 @@ typedef struct _mjmBody {
 } mjmBody;
 
 
+typedef struct _mjmJoint {
+  mjElement element;              // compiler only, do not modify
+  mjString name;                  // name
+  mjString classname;             // class name
+
+  // joint properties
+  mjtJoint type;                   // type of Joint
+  int group;                       // used for rendering
+  int limited;                     // does joint have limits: 0 false, 1 true, 2 auto
+  int actfrclimited;               // are actuator forces on joints limited: 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
+  double actfrcrange[2];           // actuator force 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
+  mjDouble userdata;               // user data
+
+  // dof properties
+  double armature;                 // armature inertia (mass for slider)
+  double damping;                  // damping coefficient
+  double frictionloss;             // friction loss
+
+  // other attributes
+  mjString info;                  // message appended to errors
+  double urdfeffort;              // store effort field from urdf
+} mjmJoint;
+
+
 typedef struct _mjmGeom {
   mjElement element;              // compiler only, do not modify
   mjString name;                  // name
@@ -131,6 +167,50 @@ typedef struct _mjmSite {
 } mjmSite;
 
 
+typedef struct _mjmCamera {
+  mjElement element;              // compiler only, do not modify
+  mjString name;                  // name
+  mjString classname;             // class name
+  mjString info;                  // message appended to errors
+  mjtCamLight mode;               // tracking mode
+  mjString targetbody;            // target body for orientation
+  double fovy;                    // y-field of view
+  double ipd;                     // inter-pupilary distance
+  double pos[3];                  // position
+  double quat[4];                 // orientation
+  float intrinsic[4];             // camera intrinsics [length]
+  float sensor_size[2];           // sensor size [length]
+  float resolution[2];            // resolution [pixel]
+  float focal_length[2];          // focal length [length]
+  float focal_pixel[2];           // focal length [pixel]
+  float principal_length[2];      // principal point [length]
+  float principal_pixel[2];       // principal point [pixel]
+  mjDouble userdata;              // user data
+  mjmOrientation alt;             // alternative orientation specification
+} mjmCamera;
+
+
+typedef struct _mjmLight {
+  mjElement element;              // compiler only, do not modify
+  mjString name;                  // name
+  mjString classname;             // class name
+  mjString info;                  // message appended to errors
+  mjtCamLight mode;               // tracking mode
+  mjString targetbody;            // target body for orientation
+  mjtByte directional;            // directional light
+  mjtByte castshadow;             // does light cast shadows
+  mjtByte 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
+} mjmLight;
+
+
 //---------------------------------- Public API ----------------------------------------------------
 
 // Create model.
@@ -139,6 +219,9 @@ MJAPI void* mjm_createModel();
 // Delete model.
 MJAPI void mjm_deleteModel(void* modelspec);
 
+// Copy spec into private attributes.
+MJAPI void mjm_finalize(mjElement object);
+
 // Add child body to body, return child spec.
 MJAPI mjmBody* mjm_addBody(mjmBody* body, void* defspec);
 
@@ -146,19 +229,19 @@ MJAPI mjmBody* mjm_addBody(mjmBody* body, void* defspec);
 MJAPI mjmSite* mjm_addSite(mjmBody* body, void* defspec);
 
 // Add joint to body.
-MJAPI void* mjm_addJoint(mjmBody* body, void* defspec);
+MJAPI mjmJoint* mjm_addJoint(mjmBody* body, void* defspec);
 
 // Add freejoint to body.
-MJAPI void* mjm_addFreeJoint(mjmBody* body);
+MJAPI mjmJoint* mjm_addFreeJoint(mjmBody* body);
 
 // Add geom to body.
 MJAPI mjmGeom* mjm_addGeom(mjmBody* body, void* defspec);
 
 // Add camera to body.
-MJAPI void* mjm_addCamera(mjmBody* body, void* defspec);
+MJAPI mjmCamera* mjm_addCamera(mjmBody* body, void* defspec);
 
 // Add light to body.
-MJAPI void* mjm_addLight(mjmBody* body, void* defspec);
+MJAPI mjmLight* mjm_addLight(mjmBody* body, void* defspec);
 
 // Add frame to body.
 MJAPI void* mjm_addFrame(mjmBody* body, void* parentframe);
@@ -208,12 +291,21 @@ MJAPI const char* mjm_setFullInertia(mjmBody* body, double quat[4], double inert
 // Default body attributes.
 MJAPI void mjm_defaultBody(mjmBody& body);
 
+// Default joint attributes.
+MJAPI void mjm_defaultJoint(mjmJoint& joint);
+
 // Default geom attributes.
 MJAPI void mjm_defaultGeom(mjmGeom& geom);
 
 // Default site attributes.
 MJAPI void mjm_defaultSite(mjmSite& site);
 
+// Default camera attributes.
+MJAPI void mjm_defaultCamera(mjmCamera& camera);
+
+// Default light attributes.
+MJAPI void mjm_defaultLight(mjmLight& light);
+
 #ifdef __cplusplus
 }
 #endif

src/user/user_composite.cc

@@ -116,7 +116,7 @@ bool mjCComposite::AddDefaultJoint(char* error, int error_sz) {
       return false;
     } else {
       mjCDef jnt;
-      jnt.joint.group = 3;
+      jnt.joint.spec.group = 3;
       defjoint[(mjtCompKind)i].push_back(jnt);
     }
   }
@@ -457,8 +457,8 @@ bool mjCComposite::MakeParticle(mjCModel* model, mjmBody* body, char* error, int
     // add slider joints if none defined
     if (!add[mjCOMPKIND_PARTICLE]) {
       for (int i=0; i<3; i++) {
-        mjCJoint* jnt = (mjCJoint*)mjm_addJoint(b, &defjoint[mjCOMPKIND_JOINT][0]);
+        mjmJoint* jnt = mjm_addJoint(b, &defjoint[mjCOMPKIND_JOINT][0]);
-        jnt->def = (mjCDef*)mjm_getDefault(body->element);
+        mjm_setDefault(jnt->element, mjm_getDefault(body->element));
         jnt->type = mjJNT_SLIDE;
         mjuu_setvec(jnt->pos, 0, 0, 0);
         mjuu_setvec(jnt->axis, 0, 0, 0);
@@ -469,8 +469,8 @@ bool mjCComposite::MakeParticle(mjCModel* model, mjmBody* body, char* error, int
     // add user-specified joints
     else {
       for (auto defjnt : defjoint[mjCOMPKIND_PARTICLE]) {
-        mjCJoint* jnt = (mjCJoint*)mjm_addJoint(b, &defjnt);
+        mjmJoint* jnt = mjm_addJoint(b, &defjnt);
-        jnt->def = (mjCDef*)mjm_getDefault(body->element);
+        mjm_setDefault(jnt->element, mjm_getDefault(body->element));
       }
     }
 
@@ -626,12 +626,12 @@ bool mjCComposite::MakeGrid(mjCModel* model, mjmBody* body, char* error, int err
       }
 
       // add slider joint
-      mjCJoint* jnt[3];
+      mjmJoint* jnt[3];
       for (int i=0; i<3; i++) {
-        jnt[i] = (mjCJoint*)mjm_addJoint(b, &defjoint[mjCOMPKIND_JOINT][0]);
+        jnt[i] = mjm_addJoint(b, &defjoint[mjCOMPKIND_JOINT][0]);
-        jnt[i]->def = (mjCDef*)mjm_getDefault(body->element);
+        mjm_setDefault(jnt[i]->element, mjm_getDefault(body->element));
         mju::sprintf_arr(txt, "%sJ%d_%d_%d", prefix.c_str(), i, ix, iy);
-        jnt[i]->name = txt;
+        mjm_setString(jnt[i]->name, txt);
         jnt[i]->type = mjJNT_SLIDE;
         mjuu_setvec(jnt[i]->pos, 0, 0, 0);
         mjuu_setvec(jnt[i]->axis, 0, 0, 0);
@@ -853,13 +853,13 @@ mjmBody* mjCComposite::AddCableBody(mjCModel* model, mjmBody* body, int ix, mjtN
 
   // add curvature joint
   if (!first || strcmp(initial.c_str(), "none")) {
-    mjCJoint* jnt = (mjCJoint*)mjm_addJoint(body, &defjoint[mjCOMPKIND_JOINT][0]);
+    mjmJoint* jnt = mjm_addJoint(body, &defjoint[mjCOMPKIND_JOINT][0]);
-    jnt->def = (mjCDef*)mjm_getDefault(body->element);
+    mjm_setDefault(jnt->element, mjm_getDefault(body->element));
     jnt->type = (first && strcmp(initial.c_str(), "free")==0) ? mjJNT_FREE : mjJNT_BALL;
     jnt->damping = jnt->type==mjJNT_FREE ? 0 : jnt->damping;
     jnt->armature = jnt->type==mjJNT_FREE ? 0 : jnt->armature;
     jnt->frictionloss = jnt->type==mjJNT_FREE ? 0 : jnt->frictionloss;
-    jnt->name = this_joint;
+    mjm_setString(jnt->name, this_joint);
   }
 
   // exclude contact pair
@@ -997,10 +997,10 @@ mjmBody* mjCComposite::AddRopeBody(mjCModel* model, mjmBody* body, int ix, int i
   // add main joint
   for (int i=0; i<2; i++) {
     // add joint
-    mjCJoint* jnt = (mjCJoint*)mjm_addJoint(body, &defjoint[mjCOMPKIND_JOINT][0]);
+    mjmJoint* jnt = mjm_addJoint(body, &defjoint[mjCOMPKIND_JOINT][0]);
-    jnt->def = (mjCDef*)mjm_getDefault(body->element);
+    mjm_setDefault(jnt->element, mjm_getDefault(body->element));
     mju::sprintf_arr(txt, "%sJ%d_%d", prefix.c_str(), i, ix1);
-    jnt->name = txt;
+    mjm_setString(jnt->name, txt);
     jnt->type = mjJNT_HINGE;
     mjuu_setvec(jnt->pos, -0.5*dx, 0, 0);
     mjuu_setvec(jnt->axis, 0, 0, 0);
@@ -1010,10 +1010,10 @@ mjmBody* mjCComposite::AddRopeBody(mjCModel* model, mjmBody* body, int ix, int i
   // add twist joint
   if (add[mjCOMPKIND_TWIST]) {
     // add joint
-    mjCJoint* jnt = (mjCJoint*)mjm_addJoint(body, &defjoint[mjCOMPKIND_TWIST][0]);
+    mjmJoint* jnt = mjm_addJoint(body, &defjoint[mjCOMPKIND_TWIST][0]);
-    jnt->def = (mjCDef*)mjm_getDefault(body->element);
+    mjm_setDefault(jnt->element, mjm_getDefault(body->element));
     mju::sprintf_arr(txt, "%sJT%d", prefix.c_str(), ix1);
-    jnt->name = txt;
+    mjm_setString(jnt->name, txt);
     jnt->type = mjJNT_HINGE;
     mjuu_setvec(jnt->pos, -0.5*dx, 0, 0);
     mjuu_setvec(jnt->axis, 1, 0, 0);
@@ -1022,16 +1022,16 @@ mjmBody* mjCComposite::AddRopeBody(mjCModel* model, mjmBody* body, int ix, int i
     mjCEquality* eq = model->AddEquality(def + mjCOMPKIND_TWIST);
     eq->def = model->defaults[0];
     eq->type = mjEQ_JOINT;
-    eq->name1 = jnt->name;
+    eq->name1 = mjm_getString(jnt->name);
   }
 
   // add stretch joint
   if (add[mjCOMPKIND_STRETCH]) {
     // add joint
-    mjCJoint* jnt = (mjCJoint*)mjm_addJoint(body, &defjoint[mjCOMPKIND_STRETCH][0]);
+    mjmJoint* jnt = mjm_addJoint(body, &defjoint[mjCOMPKIND_STRETCH][0]);
-    jnt->def = (mjCDef*)mjm_getDefault(body->element);
+    mjm_setDefault(jnt->element, mjm_getDefault(body->element));
     mju::sprintf_arr(txt, "%sJS%d", prefix.c_str(), ix1);
-    jnt->name = txt;
+    mjm_setString(jnt->name, txt);
     jnt->type = mjJNT_SLIDE;
     mjuu_setvec(jnt->pos, -0.5*dx, 0, 0);
     mjuu_setvec(jnt->axis, 1, 0, 0);
@@ -1040,7 +1040,7 @@ mjmBody* mjCComposite::AddRopeBody(mjCModel* model, mjmBody* body, int ix, int i
     mjCEquality* eq = model->AddEquality(def + mjCOMPKIND_STRETCH);
     eq->def = model->defaults[0];
     eq->type = mjEQ_JOINT;
-    eq->name1 = jnt->name;
+    eq->name1 = mjm_getString(jnt->name);
   }
 
   return body;
@@ -1149,10 +1149,10 @@ bool mjCComposite::MakeBox(mjCModel* model, mjmBody* body, char* error, int erro
           }
 
           // add slider joint
-          mjCJoint* jnt = (mjCJoint*)mjm_addJoint(b, &defjoint[mjCOMPKIND_JOINT][0]);
+          mjmJoint* jnt = mjm_addJoint(b, &defjoint[mjCOMPKIND_JOINT][0]);
-          jnt->def = (mjCDef*)mjm_getDefault(body->element);
+          mjm_setDefault(jnt->element, mjm_getDefault(body->element));
           mju::sprintf_arr(txt, "%sJ%d_%d_%d", prefix.c_str(), ix, iy, iz);
-          jnt->name = txt;
+          mjm_setString(jnt->name, txt);
           jnt->type = mjJNT_SLIDE;
           mjuu_setvec(jnt->pos, 0, 0, 0);
           mjuu_setvec(jnt->axis, 0, 0, 1);
@@ -1161,10 +1161,10 @@ bool mjCComposite::MakeBox(mjCModel* model, mjmBody* body, char* error, int erro
           mjCEquality* eq = model->AddEquality(def + mjCOMPKIND_JOINT);
           eq->def = model->defaults[0];
           eq->type = mjEQ_JOINT;
-          eq->name1 = jnt->name;
+          eq->name1 = mjm_getString(jnt->name);
 
           // add joint to tendon
-          ten->WrapJoint(jnt->name, 1);
+          ten->WrapJoint(std::string(mjm_getString(jnt->name)), 1);
 
           // add neighbor constraints
           for (int i=0; i<3; i++) {

src/user/user_flexcomp.cc

@@ -429,7 +429,7 @@ bool mjCFlexcomp::Make(mjCModel* model, mjmBody* body, char* error, int error_sz
 
       // add radial slider
       if (radial) {
-        mjCJoint* jnt = (mjCJoint*)mjm_addJoint(pb, 0);
+        mjmJoint* jnt = mjm_addJoint(pb, 0);
 
         // set properties
         jnt->type = mjJNT_SLIDE;
@@ -442,7 +442,7 @@ bool mjCFlexcomp::Make(mjCModel* model, mjmBody* body, char* error, int error_sz
       else {
         for (int j=0; j<3; j++) {
           // add joint to body
-          mjCJoint* jnt = (mjCJoint*)mjm_addJoint(pb, 0);
+          mjmJoint* jnt = mjm_addJoint(pb, 0);
 
           // set properties
           jnt->type = mjJNT_SLIDE;

src/user/user_init.cc

@@ -38,8 +38,23 @@ void mjm_defaultBody(mjmBody& body) {
 }
 
 
+
+// default joint attributes
+void mjm_defaultJoint(mjmJoint& joint) {
+  memset(&joint, 0, sizeof(mjmJoint));
+  joint.type = mjJNT_HINGE;
+  joint.axis[2] = 1;
+  joint.limited = 2;
+  joint.actfrclimited = 2;
+  mj_defaultSolRefImp(joint.solref_limit, joint.solimp_limit);
+  mj_defaultSolRefImp(joint.solref_friction, joint.solimp_friction);
+  joint.urdfeffort = -1;
+}
+
+
+
 // default geom attributes
-MJAPI void mjm_defaultGeom(mjmGeom& geom) {
+void mjm_defaultGeom(mjmGeom& geom) {
   memset(&geom, 0, sizeof(mjmGeom));
 
   // set non-zero defaults
@@ -83,3 +98,36 @@ void mjm_defaultSite(mjmSite& site) {
   site.rgba[0] = site.rgba[1] = site.rgba[2] = 0.5f;
   site.rgba[3] = 1.0f;
 }
+
+
+
+// default cam attributes
+void mjm_defaultCamera(mjmCamera& cam) {
+  memset(&cam, 0, sizeof(mjmCamera));
+  cam.mode = mjCAMLIGHT_FIXED;
+  cam.quat[0] = 1;
+  cam.fovy = 45;
+  cam.ipd = 0.068;
+  cam.resolution[0] = cam.resolution[1] = 1;
+  cam.alt.axisangle[0] = cam.alt.xyaxes[0] = cam.alt.zaxis[0] = cam.alt.euler[0] = mjNAN;
+}
+
+
+
+// default light attributes
+void mjm_defaultLight(mjmLight& light) {
+  memset(&light, 0, sizeof(mjmLight));
+  light.mode = mjCAMLIGHT_FIXED;
+  light.directional = 0;
+  light.castshadow = 1;
+  light.active = 1;
+  light.dir[2] = -1;
+  light.attenuation[0] = 1;
+  light.cutoff = 45;
+  light.exponent = 10;
+  light.ambient[0] = light.ambient[1] = light.ambient[2] = 0;
+  light.diffuse[0] = light.diffuse[1] = light.diffuse[2] = 0.7;
+  light.specular[0] = light.specular[1] = light.specular[2] = 0.3;
+}
+
+

src/user/user_model.cc

@@ -565,7 +565,7 @@ mjCDef* mjCModel::AddDef(string name, int parentid) {
   if (parentid>=0 && parentid<thisid) {
     *def = *defaults[parentid];
     defaults[parentid]->childid.push_back(thisid);
-    def->MakePointerLocal();
+    def->PointToLocal();
   }
   def->parentid = parentid;
   def->name = name;
@@ -1573,7 +1573,7 @@ void mjCModel::CopyTree(mjModel* m) {
       copyvec(m->jnt_solref+mjNREF*jid, pj->solref_limit, mjNREF);
       copyvec(m->jnt_solimp+mjNIMP*jid, pj->solimp_limit, mjNIMP);
       m->jnt_margin[jid] = (mjtNum)pj->margin;
-      copyvec(m->jnt_user+nuser_jnt*jid, pj->userdata.data(), nuser_jnt);
+      copyvec(m->jnt_user+nuser_jnt*jid, pj->get_userdata().data(), nuser_jnt);
 
       // not simple if: rotation already found, or pos not zero, or mis-aligned axis
       if (rotfound ||
@@ -1756,7 +1756,7 @@ void mjCModel::CopyTree(mjModel* m) {
       copyvec(m->cam_resolution+2*cid, pc->resolution, 2);
       copyvec(m->cam_sensorsize+2*cid, pc->sensor_size, 2);
       copyvec(m->cam_intrinsic+4*cid, pc->intrinsic, 4);
-      copyvec(m->cam_user+nuser_cam*cid, pc->userdata.data(), nuser_cam);
+      copyvec(m->cam_user+nuser_cam*cid, pc->get_userdata().data(), nuser_cam);
     }
 
     // loop over lights for this body
@@ -2890,7 +2890,7 @@ void mjCModel::TryCompile(mjModel*& m, mjData*& d, const mjVFS* vfs) {
   if (nuser_jnt == -1) {
     nuser_jnt = 0;
     for (int i=0; i<joints.size(); i++) {
-      nuser_jnt = mjMAX(nuser_jnt, joints[i]->userdata.size());
+      nuser_jnt = mjMAX(nuser_jnt, joints[i]->spec_userdata_.size());
     }
   }
   if (nuser_geom == -1) {
@@ -2908,7 +2908,7 @@ void mjCModel::TryCompile(mjModel*& m, mjData*& d, const mjVFS* vfs) {
   if (nuser_cam == -1) {
     nuser_cam = 0;
     for (int i=0; i<cameras.size(); i++) {
-      nuser_cam = mjMAX(nuser_cam, cameras[i]->userdata.size());
+      nuser_cam = mjMAX(nuser_cam, cameras[i]->spec_userdata_.size());
     }
   }
   if (nuser_tendon == -1) {
@@ -3341,7 +3341,7 @@ bool mjCModel::CopyBack(const mjModel* m) {
     pj->margin = (double)m->jnt_margin[i];
 
     if (nuser_jnt) {
-      copyvec(pj->userdata.data(), m->jnt_user + nuser_jnt*i, nuser_jnt);
+      copyvec(pj->userdata_.data(), m->jnt_user + nuser_jnt*i, nuser_jnt);
     }
 
     // dof data
@@ -3422,7 +3422,7 @@ bool mjCModel::CopyBack(const mjModel* m) {
     copyvec(cameras[i]->intrinsic, m->cam_intrinsic+4*i, 4);
 
     if (nuser_cam) {
-      copyvec(cameras[i]->userdata.data(), m->cam_user + nuser_cam*i, nuser_cam);
+      copyvec(cameras[i]->userdata_.data(), m->cam_user + nuser_cam*i, nuser_cam);
     }
   }
 

src/user/user_objects.cc

@@ -470,10 +470,10 @@ mjCDef::mjCDef(void) {
 // compiler
 void mjCDef::Compile(const mjCModel* model) {
   // enforce length of all default userdata arrays
-  joint.userdata.resize(model->nuser_jnt);
+  joint.userdata_.resize(model->nuser_jnt);
   geom.userdata_.resize(model->nuser_geom);
   site.userdata_.resize(model->nuser_site);
-  camera.userdata.resize(model->nuser_cam);
+  camera.userdata_.resize(model->nuser_cam);
   tendon.userdata.resize(model->nuser_tendon);
   actuator.userdata.resize(model->nuser_actuator);
 }
@@ -481,8 +481,11 @@ void mjCDef::Compile(const mjCModel* model) {
 
 
 // assignment operator (TODO: use overloading)
-void mjCDef::MakePointerLocal() {
+void mjCDef::PointToLocal() {
-  geom.MakePointerLocal();
+  joint.PointToLocal();
+  geom.PointToLocal();
+  site.PointToLocal();
+  camera.PointToLocal();
 }
 
 
@@ -581,16 +584,21 @@ mjCBody::mjCBody(mjCModel* _model) {
   lights.clear();
   spec_userdata_.clear();
 
-  // point to local
+  // in case this body is not compiled
+  CopyFromSpec();
+
+  // point to local (needs to be after defaults)
+  PointToLocal();
+}
+
+
+void mjCBody::PointToLocal() {
   spec.element = (mjElement)this;
   spec.name = (mjString)&name;
   spec.classname = (mjString)&classname;
   spec.userdata = (mjDouble)&spec_userdata_;
   spec.plugin.name = (mjString)&plugin_name;
   spec.plugin.instance_name = (mjString)&plugin_instance_name;
-
-  // in case this body is not compiled
-  CopyFromSpec();
 }
 
 
@@ -664,7 +672,7 @@ mjCFrame* mjCBody::AddFrame(mjCFrame* _frame) {
 mjCJoint* mjCBody::AddFreeJoint() {
   // create free joint, don't inherit from defaults
   mjCJoint* obj = new mjCJoint(model, NULL);
-  obj->type = mjJNT_FREE;
+  obj->spec.type = mjJNT_FREE;
 
   // set body pointer, add
   obj->body = this;
@@ -1200,56 +1208,59 @@ void mjCFrame::Compile() {
 
 // initialize default joint
 mjCJoint::mjCJoint(mjCModel* _model, mjCDef* _def) {
-  // joint defaults
+  mjm_defaultJoint(spec);
-  type = mjJNT_HINGE;
-  group = 0;
-  mjuu_setvec(pos, 0, 0, 0);
-  mjuu_setvec(axis, 0, 0, 1);
-  limited = 2;
-  actfrclimited = 2;
-  stiffness = 0;
-  range[0] = 0;
-  range[1] = 0;
-  actfrcrange[0] = 0;
-  actfrcrange[1] = 0;
-  springdamper[0] = 0;
-  springdamper[1] = 0;
-  mj_defaultSolRefImp(solref_limit, solimp_limit);
-  mj_defaultSolRefImp(solref_friction, solimp_friction);
-  margin = 0;
-  ref = 0;
-  springref = 0;
-  userdata.clear();
-
-  // dof defaults
-  armature = 0;
-  frictionloss = 0;
-  damping = 0;
 
   // clear internal variables
+  spec_userdata_.clear();
   body = 0;
-  urdfeffort = -1;
 
   // reset to default if given
   if (_def) {
+    _def->joint.CopyFromSpec();
     *this = _def->joint;
   }
 
   // set model, def
   model = _model;
   def = (_def ? _def : (_model ? _model->defaults[0] : 0));
+
+  // point to local (needs to be after defaults)
+  PointToLocal();
+
+  // in case this joint is not compiled
+  CopyFromSpec();
+}
+
+
+
+void mjCJoint::PointToLocal() {
+  spec.element = (mjElement)this;
+  spec.name = (mjString)&name;
+  spec.classname = (mjString)&classname;
+  spec.userdata = (mjDouble)&spec_userdata_;
+  spec.info = (mjString)&info;
+}
+
+
+
+void mjCJoint::CopyFromSpec() {
+  *static_cast<mjmJoint*>(this) = spec;
+  userdata_ = spec_userdata_;
+  userdata = (mjDouble)&spec_userdata_;
 }
 
 
 
 // compiler
 int mjCJoint::Compile(void) {
+  CopyFromSpec();
+
   // resize userdata
-  if (userdata.size() > model->nuser_jnt) {
+  if (userdata_.size() > model->nuser_jnt) {
     throw mjCError(this, "user has more values than nuser_jnt in joint '%s' (id = %d)",
                    name.c_str(), id);
   }
-  userdata.resize(model->nuser_jnt);
+  userdata_.resize(model->nuser_jnt);
 
   // check springdamper
   if (springdamper[0] || springdamper[1]) {
@@ -1405,7 +1416,7 @@ mjCGeom::mjCGeom(mjCModel* _model, mjCDef* _def) {
   def = (_def ? _def : (_model ? _model->defaults[0] : 0));
 
   // point to local (needs to be after defaults)
-  MakePointerLocal();
+  PointToLocal();
 
   // in case this geom is not compiled
   CopyFromSpec();
@@ -1414,7 +1425,7 @@ mjCGeom::mjCGeom(mjCModel* _model, mjCDef* _def) {
 
 
 // to be called after any default copy constructor
-void mjCGeom::MakePointerLocal(void) {
+void mjCGeom::PointToLocal(void) {
   spec.element = (mjElement)this;
   spec.name = (mjString)&name;
   spec.info = (mjString)&info;
@@ -2001,20 +2012,26 @@ mjCSite::mjCSite(mjCModel* _model, mjCDef* _def) {
     *this = _def->site;
   }
 
-  // point to local, not to default
+  // point to local (needs to be after defaults)
+  PointToLocal();
+
+  // in case this site is not compiled
+  CopyFromSpec();
+
+  // set model, def
+  model = _model;
+  def = (_def ? _def : (_model ? _model->defaults[0] : 0));
+}
+
+
+
+void mjCSite::PointToLocal() {
   spec.element = (mjElement)this;
   spec.name = (mjString)&name;
   spec.info = (mjString)&info;
   spec.classname = (mjString)&classname;
   spec.material = (mjString)&spec_material_;
   spec.userdata = (mjDouble)&spec_userdata_;
-
-  // initialize private attributes in case object won't be compiled
-  CopyFromSpec();
-
-  // set model, def
-  model = _model;
-  def = (_def ? _def : (_model ? _model->defaults[0] : 0));
 }
 
 
@@ -2124,49 +2141,70 @@ void mjCSite::Compile(void) {
 
 // initialize defaults
 mjCCamera::mjCCamera(mjCModel* _model, mjCDef* _def) {
-  // set defaults
+  mjm_defaultCamera(spec);
-  mode = mjCAMLIGHT_FIXED;
-  targetbody.clear();
-  mjuu_setvec(pos, 0, 0, 0);
-  mjuu_setvec(quat, 1, 0, 0, 0);
-  fovy = 45;
-  ipd = 0.068;
-  userdata.clear();
-  resolution[0] = resolution[1] = 1;
-  principal_length[0] = principal_length[1] = 0;
-  principal_pixel[0] = principal_pixel[1] = 0;
-  focal_length[0] = focal_length[1] = 0;
-  focal_pixel[0] = focal_pixel[1] = 0;
-  sensor_size[0] = sensor_size[1] = 0;
-  mjuu_setvec(intrinsic, 0, 0, 0, 0);
 
   // clear private variables
   body = 0;
   targetbodyid = -1;
+  spec_targetbody_.clear();
 
   // reset to default if given
   if (_def) {
+    _def->camera.CopyFromSpec();
     *this = _def->camera;
   }
 
   // set model, def
   model = _model;
   def = (_def ? _def : (_model ? _model->defaults[0] : 0));
+
+  // point to local (needs to be after defaults)
+  PointToLocal();
+
+  // in case this camera is not compiled
+  CopyFromSpec();
+}
+
+
+
+void mjCCamera::PointToLocal() {
+  spec.element = (mjElement)this;
+  spec.name = (mjString)&name;
+  spec.classname = (mjString)&classname;
+  spec.userdata = (mjDouble)&spec_userdata_;
+  spec.targetbody = (mjString)&spec_targetbody_;
+  spec.info = (mjString)&info;
+}
+
+
+
+void mjCCamera::CopyFromSpec() {
+  *static_cast<mjmCamera*>(this) = spec;
+  userdata_ = spec_userdata_;
+  targetbody_ = spec_targetbody_;
+  userdata = (mjDouble)&userdata_;
+  targetbody = (mjString)&targetbody_;
+  mju_copy4(alt_.axisangle, alt.axisangle);
+  mju_copy(alt_.xyaxes, alt.xyaxes, 6);
+  mju_copy3(alt_.zaxis, alt.zaxis);
+  mju_copy3(alt_.euler, alt.euler);
 }
 
 
 
 // compiler
 void mjCCamera::Compile(void) {
+  CopyFromSpec();
+
   // resize userdata
-  if (userdata.size() > model->nuser_cam) {
+  if (userdata_.size() > model->nuser_cam) {
     throw mjCError(this, "user has more values than nuser_cam in camera '%s' (id = %d)",
                    name.c_str(), id);
   }
-  userdata.resize(model->nuser_cam);
+  userdata_.resize(model->nuser_cam);
 
   // process orientation specifications
-  const char* err = alt.Set(quat, model->degree, model->euler);
+  const char* err = alt_.Set(quat, model->degree, model->euler);
   if (err) {
     throw mjCError(this, "orientation specification error '%s' in camera %d", err, id);
   }
@@ -2180,8 +2218,8 @@ void mjCCamera::Compile(void) {
   mjuu_normvec(quat, 4);
 
   // get targetbodyid
-  if (!targetbody.empty()) {
+  if (!targetbody_.empty()) {
-    mjCBody* tb = (mjCBody*)model->FindObject(mjOBJ_BODY, targetbody);
+    mjCBody* tb = (mjCBody*)model->FindObject(mjOBJ_BODY, targetbody_);
     if (tb) {
       targetbodyid = tb->id;
     } else {
@@ -2240,39 +2278,47 @@ void mjCCamera::Compile(void) {
 
 // initialize defaults
 mjCLight::mjCLight(mjCModel* _model, mjCDef* _def) {
-  // set defaults
+  mjm_defaultLight(spec);
-  mode = mjCAMLIGHT_FIXED;
-  targetbody.clear();
-  directional = false;
-  castshadow = true;
-  active = true;
-  mjuu_setvec(pos, 0, 0, 0);
-  mjuu_setvec(dir, 0, 0, -1);
-  mjuu_setvec(attenuation, 1, 0, 0);
-  cutoff = 45;
-  exponent = 10;
-  ambient[0] = ambient[1] = ambient[2] = 0;
-  diffuse[0] = diffuse[1] = diffuse[2] = 0.7;
-  specular[0] = specular[1] = specular[2] = 0.3;
 
   // clear private variables
   body = 0;
   targetbodyid = -1;
+  spec_targetbody_.clear();
 
   // reset to default if given
   if (_def) {
+    _def->light.CopyFromSpec();
     *this = _def->light;
   }
 
   // set model, def
   model = _model;
   def = (_def ? _def : (_model ? _model->defaults[0] : 0));
+
+  // point to local
+  spec.element = (mjElement)this;
+  spec.name = (mjString)&name;
+  spec.classname = (mjString)&classname;
+  spec.targetbody = (mjString)&spec_targetbody_;
+  spec.info = (mjString)&info;
+
+  CopyFromSpec();
+}
+
+
+
+void mjCLight::CopyFromSpec() {
+  *static_cast<mjmLight*>(this) = spec;
+  targetbody_ = spec_targetbody_;
+  targetbody = (mjString)&targetbody_;
 }
 
 
 
 // compiler
 void mjCLight::Compile(void) {
+  CopyFromSpec();
+
   double quat[4]= {1, 0, 0, 0};
 
   // frame
@@ -2286,8 +2332,8 @@ void mjCLight::Compile(void) {
   }
 
   // get targetbodyid
-  if (!targetbody.empty()) {
+  if (!targetbody_.empty()) {
-    mjCBody* tb = (mjCBody*)model->FindObject(mjOBJ_BODY, targetbody);
+    mjCBody* tb = (mjCBody*)model->FindObject(mjOBJ_BODY, targetbody_);
     if (tb) {
       targetbodyid = tb->id;
     } else {
@@ -4077,9 +4123,9 @@ void mjCActuator::Compile(void) {
     pjnt = (mjCJoint*) ptarget;
 
     // apply urdfeffort
-    if (pjnt->urdfeffort>0) {
+    if (pjnt->spec.urdfeffort>0) {
-      forcerange[0] = -pjnt->urdfeffort;
+      forcerange[0] = -pjnt->spec.urdfeffort;
-      forcerange[1] = pjnt->urdfeffort;
+      forcerange[1] = pjnt->spec.urdfeffort;
       forcelimited = 1;
     }
     break;

src/user/user_objects.h

@@ -180,6 +180,9 @@ class mjCBase {
   // Add frame transformation
   void SetFrame(mjCFrame* _frame);
 
+  // Copy spec into private attributes
+  virtual void CopyFromSpec() {}
+
   std::string name;               // object name
   std::string classname;          // defaults class name
   int id;                         // object id
@@ -194,6 +197,7 @@ class mjCBase {
   std::string plugin_instance_name;
  protected:
   mjCBase();                      // constructor
+  virtual ~mjCBase() = default;   // destructor
 };
 
 
@@ -289,6 +293,7 @@ class mjCBody : public mjCBase, private mjmBody {
   std::vector<mjCLight*>   lights;     // lights attached to this body
 
   void CopyFromSpec();                 // copy spec into attributes
+  void PointToLocal(void);
 
   // variable-size data
   std::vector<double> userdata_;
@@ -322,48 +327,36 @@ class mjCFrame : public mjCBase {
 //------------------------- class mjCJoint ---------------------------------------------------------
 // Describes a motion degree of freedom of a body relative to its parent
 
-class mjCJoint : public mjCBase {
+class mjCJoint : public mjCBase, private mjmJoint {
   friend class mjCDef;
   friend class mjCEquality;
   friend class mjCBody;
   friend class mjCModel;
+  friend class mjCSensor;
   friend class mjXWriter;
   friend class mjXURDF;
 
  public:
-  // variables set by user: joint properties
+  mjmJoint spec;
-  mjtJoint type;                   // type of Joint
+  using mjCBase::name;
-  int group;                       // used for rendering
+  using mjCBase::classname;
-  int limited;                     // does joint have limits: 0 false, 1 true, 2 auto
+  using mjCBase::info;
-  int actfrclimited;               // are actuator forces on joints limited: 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
-  double actfrcrange[2];           // actuator force 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
+  void CopyFromSpec(void);
-  double armature;                 // armature inertia (mass for slider)
-  double damping;                  // damping coefficient
-  double frictionloss;             // friction loss
 
-  double urdfeffort;               // store effort field from urdf
+  // used by mjXWriter and mjCModel
+  const std::vector<double>& get_userdata() { return userdata_; }
 
  private:
   mjCJoint(mjCModel* = 0, mjCDef* = 0);
 
   int Compile(void);               // compiler; return dofnum
+  void PointToLocal(void);
 
   mjCBody* body;                   // joint's body
+  // variable-size data
+  std::vector<double> userdata_;
+  std::vector<double> spec_userdata_;
 };
 
 
@@ -412,7 +405,7 @@ class mjCGeom : public mjCBase, private mjmGeom {
   double GetRBound(void);             // compute bounding sphere radius
   void ComputeAABB(void);             // compute axis-aligned bounding box
   void CopyFromSpec(void);
-  void MakePointerLocal(void);
+  void PointToLocal(void);
 
   mjCAlternative alt_;
   bool visual_;                       // true: geom does not collide and is unreferenced
@@ -470,6 +463,7 @@ class mjCSite : public mjCBase, private mjmSite {
   mjCSite(mjCModel* = 0, mjCDef* = 0);    // constructor
   void Compile(void);                     // compiler
   void CopyFromSpec();                    // copy spec into attributes
+  void PointToLocal(void);
 
   mjCAlternative alt_;
 
@@ -489,36 +483,36 @@ class mjCSite : public mjCBase, private mjmSite {
 //------------------------- class mjCCamera --------------------------------------------------------
 // Describes a camera, attached to a body
 
-class mjCCamera : public mjCBase {
+class mjCCamera : public mjCBase, private mjmCamera {
   friend class mjCDef;
   friend class mjCBody;
   friend class mjCModel;
+  friend class mjCSensor;
   friend class mjXWriter;
 
  public:
-  // variables set by user
+  mjmCamera spec;
-  mjtCamLight mode;               // tracking mode
+  using mjCBase::name;
-  std::string targetbody;         // target body for orientation
+  using mjCBase::classname;
-  double fovy;                    // y-field of view
+  using mjCBase::info;
-  double ipd;                     // inter-pupilary distance
+
-  double pos[3];                  // position
+  // used by mjXWriter and mjCModel
-  double quat[4];                 // orientation
+  const std::string& get_targetbody() { return targetbody_; }
-  float intrinsic[4];             // camera intrinsics [length]
+  const std::vector<double>& get_userdata() { return userdata_; }
-  float sensor_size[2];           // sensor size [length]
-  float resolution[2];            // resolution [pixel]
-  float focal_length[2];          // focal length [length]
-  float focal_pixel[2];           // focal length [pixel]
-  float principal_length[2];      // principal point [length]
-  float principal_pixel[2];       // principal point [pixel]
-  std::vector<double> userdata;   // user data
-  mjCAlternative alt;             // alternative orientation specification
 
  private:
   mjCCamera(mjCModel* = 0, mjCDef* = 0);  // constructor
   void Compile(void);                     // compiler
+  void CopyFromSpec(void);
+  void PointToLocal(void);
 
   mjCBody* body;                  // camera's body
   int targetbodyid;               // id of target body; -1: none
+  mjCAlternative alt_;
+  std::string targetbody_;
+  std::string spec_targetbody_;
+  std::vector<double> userdata_;
+  std::vector<double> spec_userdata_;
 };
 
 
@@ -526,34 +520,30 @@ class mjCCamera : public mjCBase {
 //------------------------- class mjCLight ---------------------------------------------------------
 // Describes a light, attached to a body
 
-class mjCLight : public mjCBase {
+class mjCLight : public mjCBase, private mjmLight {
   friend class mjCDef;
   friend class mjCBody;
   friend class mjCModel;
   friend class mjXWriter;
 
  public:
-  // variables set by user
+  mjmLight spec;
-  mjtCamLight mode;               // tracking mode
+  using mjCBase::name;
-  std::string targetbody;         // target body for orientation
+  using mjCBase::classname;
-  bool directional;               // directional light
+  using mjCBase::info;
-  bool castshadow;                // does light cast shadows
+
-  bool active;                    // is light active
+  // used by mjXWriter and mjCModel
-  double pos[3];                  // position
+  const std::string& get_targetbody() { return targetbody_; }
-  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
+  void CopyFromSpec(void);
 
   mjCBody* body;                  // light's body
   int targetbodyid;               // id of target body; -1: none
+  std::string targetbody_;
+  std::string spec_targetbody_;
 };
 
 
@@ -1314,7 +1304,7 @@ class mjCDef {
  public:
   mjCDef(void);                           // constructor
   void Compile(const mjCModel* model);    // compiler
-  void MakePointerLocal();
+  void PointToLocal();
 
   // identifiers
   std::string name;               // class name

src/xml/xml_native_reader.cc

@@ -1465,13 +1465,18 @@ void mjXReader::OneMaterial(XMLElement* elem, mjCMaterial* pmat) {
 
 
 // joint element parser
-void mjXReader::OneJoint(XMLElement* elem, mjCJoint* pjoint) {
+void mjXReader::OneJoint(XMLElement* elem, mjmJoint* pjoint) {
-  string text;
+  string text, name, classname;
+  std::vector<double> userdata;
   int n;
 
   // read attributes
-  ReadAttrTxt(elem, "name", pjoint->name);
+  if (ReadAttrTxt(elem, "name", name)) {
-  ReadAttrTxt(elem, "class", pjoint->classname);
+    mjm_setString(pjoint->name, name.c_str());
+  }
+  if (ReadAttrTxt(elem, "class", classname)) {
+    mjm_setString(pjoint->classname, classname.c_str());
+  }
   if (MapValue(elem, "type", &n, joint_map, joint_sz)) {
     pjoint->type = (mjtJoint)n;
   }
@@ -1496,9 +1501,13 @@ void mjXReader::OneJoint(XMLElement* elem, mjCJoint* pjoint) {
   ReadAttr(elem, "frictionloss", 1, &pjoint->frictionloss, text);
 
   // read userdata
-  ReadVector(elem, "user", pjoint->userdata, text);
+  if (ReadVector(elem, "user", userdata, text)) {
+    mjm_setDouble(pjoint->userdata, userdata.data(), userdata.size());
+  }
 
-  GetXMLPos(elem, pjoint);
+  // write error info
+  mjm_setString(pjoint->info,
+      std::string("line = " + std::to_string(elem->GetLineNum()) + ", column = -1").c_str());
 }
 
 
@@ -1572,6 +1581,7 @@ void mjXReader::OneGeom(XMLElement* elem, mjmGeom* pgeom) {
     pgeom->typeinertia = (mjtGeomInertia)n;
   }
 
+  // write error info
   mjm_setString(pgeom->info,
       std::string("line = " + std::to_string(elem->GetLineNum()) + ", column = -1").c_str());
 }
@@ -1586,8 +1596,12 @@ void mjXReader::OneSite(XMLElement* elem, mjmSite& site) {
   std::string material;
 
   // read attributes
-  ReadAttrTxt(elem, "name", name);
+  if (ReadAttrTxt(elem, "name", name)) {
-  ReadAttrTxt(elem, "class", classname);
+    mjm_setString(site.name, name.c_str());
+  }
+  if (ReadAttrTxt(elem, "class", classname)) {
+    mjm_setString(site.classname, classname.c_str());
+  }
   if (MapValue(elem, "type", &n, geom_map, mjNGEOMTYPES)) {
     site.type = (mjtGeom)n;
   }
@@ -1595,21 +1609,17 @@ void mjXReader::OneSite(XMLElement* elem, mjmSite& site) {
   ReadAttrInt(elem, "group", &site.group);
   ReadAttr(elem, "pos", 3, site.pos, text);
   ReadQuat(elem, "quat", site.quat, text);
-  ReadAttrTxt(elem, "material", material);
+  if (ReadAttrTxt(elem, "material", material)) {
+    mjm_setString(site.material, material.c_str());
+  }
   ReadAttr(elem, "rgba", 4, site.rgba, text);
   ReadAttr(elem, "fromto", 6, site.fromto, text);
   ReadAlternative(elem, site.alt);
-  ReadVector(elem, "user", userdata, text);
+  if (ReadVector(elem, "user", userdata, text)) {
+    mjm_setDouble(site.userdata, userdata.data(), userdata.size());
+  }
 
-  // set strings
+  // write error info
-  mjm_setString(site.name, name.c_str());
-  mjm_setString(site.classname, classname.c_str());
-  mjm_setString(site.material, material.c_str());
-
-  // set pointers
-  mjm_setDouble(site.userdata, userdata.data(), userdata.size());
-
-  // set info
   mjm_setString(site.info,
       std::string("line = " + std::to_string(elem->GetLineNum()) + ", column = -1").c_str());
 }
@@ -1617,14 +1627,21 @@ void mjXReader::OneSite(XMLElement* elem, mjmSite& site) {
 
 
 // camera element parser
-void mjXReader::OneCamera(XMLElement* elem, mjCCamera* pcam) {
+void mjXReader::OneCamera(XMLElement* elem, mjmCamera* pcam) {
   int n;
-  string text;
+  string text, name, classname, targetbody;
+  std::vector<double> userdata;
 
   // read attributes
-  ReadAttrTxt(elem, "name", pcam->name);
+  if (ReadAttrTxt(elem, "name", name)) {
-  ReadAttrTxt(elem, "class", pcam->classname);
+    mjm_setString(pcam->name, name.c_str());
-  ReadAttrTxt(elem, "target", pcam->targetbody);
+  }
+  if (ReadAttrTxt(elem, "class", classname)) {
+    mjm_setString(pcam->classname, classname.c_str());
+  }
+  if (ReadAttrTxt(elem, "target", targetbody)) {
+    mjm_setString(pcam->targetbody, targetbody.c_str());
+  }
   if (MapValue(elem, "mode", &n, camlight_map, camlight_sz)) {
     pcam->mode = (mjtCamLight)n;
   }
@@ -1654,22 +1671,31 @@ void mjXReader::OneCamera(XMLElement* elem, mjCCamera* pcam) {
   }
 
   // read userdata
-  ReadVector(elem, "user", pcam->userdata, text);
+  ReadVector(elem, "user", userdata, text);
+  mjm_setDouble(pcam->userdata, userdata.data(), userdata.size());
 
-  GetXMLPos(elem, pcam);
+  // write error info
+  mjm_setString(pcam->info,
+      std::string("line = " + std::to_string(elem->GetLineNum()) + ", column = -1").c_str());
 }
 
 
 
 // light element parser
-void mjXReader::OneLight(XMLElement* elem, mjCLight* plight) {
+void mjXReader::OneLight(XMLElement* elem, mjmLight* plight) {
   int n;
-  string text;
+  string text, name, classname, targetbody;
 
   // read attributes
-  ReadAttrTxt(elem, "name", plight->name);
+  if (ReadAttrTxt(elem, "name", name)) {
-  ReadAttrTxt(elem, "class", plight->classname);
+    mjm_setString(plight->name, name.c_str());
-  ReadAttrTxt(elem, "target", plight->targetbody);
+  }
+  if (ReadAttrTxt(elem, "class", classname)) {
+    mjm_setString(plight->classname, classname.c_str());
+  }
+  if (ReadAttrTxt(elem, "target", targetbody)) {
+    mjm_setString(plight->targetbody, targetbody.c_str());
+  }
   if (MapValue(elem, "mode", &n, camlight_map, camlight_sz)) {
     plight->mode = (mjtCamLight)n;
   }
@@ -1691,7 +1717,9 @@ void mjXReader::OneLight(XMLElement* elem, mjCLight* plight) {
   ReadAttr(elem, "diffuse", 3, plight->diffuse, text);
   ReadAttr(elem, "specular", 3, plight->specular, text);
 
-  GetXMLPos(elem, plight);
+  // write error info
+  mjm_setString(plight->info,
+      std::string("line = " + std::to_string(elem->GetLineNum()) + ", column = -1").c_str());
 }
 
 
@@ -2226,29 +2254,29 @@ void mjXReader::OneComposite(XMLElement* elem, mjmBody* pbody, mjCDef* def) {
 
     // particle joint
     if (MapValue(ejnt, "type", &n, joint_map, joint_sz)) {
-      el->joint.type = (mjtJoint)n;
+      el->joint.spec.type = (mjtJoint)n;
     }
-    ReadAttr(ejnt, "axis", 3, el->joint.axis, text);
+    ReadAttr(ejnt, "axis", 3, el->joint.spec.axis, text);
 
     // solreffix, solimpfix
     ReadAttr(ejnt, "solreffix", mjNREF, el->equality.solref, text, false, false);
     ReadAttr(ejnt, "solimpfix", mjNIMP, el->equality.solimp, text, false, false);
 
     // joint attributes
-    MapValue(elem, "limited", &el->joint.limited, TFAuto_map, 3);
+    MapValue(elem, "limited", &el->joint.spec.limited, TFAuto_map, 3);
-    ReadAttrInt(ejnt, "group", &el->joint.group);
+    ReadAttrInt(ejnt, "group", &el->joint.spec.group);
-    ReadAttr(ejnt, "solreflimit", mjNREF, el->joint.solref_limit, text, false, false);
+    ReadAttr(ejnt, "solreflimit", mjNREF, el->joint.spec.solref_limit, text, false, false);
-    ReadAttr(ejnt, "solimplimit", mjNIMP, el->joint.solimp_limit, text, false, false);
+    ReadAttr(ejnt, "solimplimit", mjNIMP, el->joint.spec.solimp_limit, text, false, false);
     ReadAttr(ejnt,
-             "solreffriction", mjNREF, el->joint.solref_friction, text, false, false);
+             "solreffriction", mjNREF, el->joint.spec.solref_friction, text, false, false);
     ReadAttr(ejnt,
-             "solimpfriction", mjNIMP, el->joint.solimp_friction, text, false, false);
+             "solimpfriction", mjNIMP, el->joint.spec.solimp_friction, text, false, false);
-    ReadAttr(ejnt, "stiffness", 1, &el->joint.stiffness, text);
+    ReadAttr(ejnt, "stiffness", 1, &el->joint.spec.stiffness, text);
-    ReadAttr(ejnt, "range", 2, el->joint.range, text);
+    ReadAttr(ejnt, "range", 2, el->joint.spec.range, text);
-    ReadAttr(ejnt, "margin", 1, &el->joint.margin, text);
+    ReadAttr(ejnt, "margin", 1, &el->joint.spec.margin, text);
-    ReadAttr(ejnt, "armature", 1, &el->joint.armature, text);
+    ReadAttr(ejnt, "armature", 1, &el->joint.spec.armature, text);
-    ReadAttr(ejnt, "damping", 1, &el->joint.damping, text);
+    ReadAttr(ejnt, "damping", 1, &el->joint.spec.damping, text);
-    ReadAttr(ejnt, "frictionloss", 1, &el->joint.frictionloss, text);
+    ReadAttr(ejnt, "frictionloss", 1, &el->joint.spec.frictionloss, text);
 
     // advance
     ejnt = ejnt->NextSiblingElement("joint");
@@ -2510,7 +2538,7 @@ void mjXReader::Default(XMLElement* section, int parentid) {
     else if (name=="material") OneMaterial(elem, &def->material);
 
     // read joint
-    else if (name=="joint") OneJoint(elem, &def->joint);
+    else if (name=="joint") OneJoint(elem, &def->joint.spec);
 
     // read geom
     else if (name=="geom") OneGeom(elem, &def->geom.spec);
@@ -2519,10 +2547,10 @@ void mjXReader::Default(XMLElement* section, int parentid) {
     else if (name=="site") OneSite(elem, def->site.spec);
 
     // read camera
-    else if (name=="camera") OneCamera(elem, &def->camera);
+    else if (name=="camera") OneCamera(elem, &def->camera.spec);
 
     // read light
-    else if (name=="light") OneLight(elem, &def->light);
+    else if (name=="light") OneLight(elem, &def->light.spec);
 
     // read pair
     else if (name=="pair") OnePair(elem, &def->pair);
@@ -2546,6 +2574,13 @@ void mjXReader::Default(XMLElement* section, int parentid) {
       OneActuator(elem, &def->actuator);
     }
 
+    // copy into private attributes
+    mjm_finalize(def->geom.spec.element);
+    mjm_finalize(def->joint.spec.element);
+    mjm_finalize(def->site.spec.element);
+    mjm_finalize(def->camera.spec.element);
+    mjm_finalize(def->light.spec.element);
+
     // advance
     elem = elem->NextSiblingElement();
   }
@@ -3059,9 +3094,9 @@ void mjXReader::Body(XMLElement* section, mjmBody* pbody, mjCFrame* frame) {
       }
 
       // create joint and parse
-      mjCJoint* pjoint = (mjCJoint*)mjm_addJoint(pbody, def);
+      mjmJoint* pjoint = mjm_addJoint(pbody, def);
       OneJoint(elem, pjoint);
-      pjoint->SetFrame(frame);
+      mjm_setFrame(pjoint->element, frame);
     }
 
     // freejoint sub-element
@@ -3072,14 +3107,17 @@ void mjXReader::Body(XMLElement* section, mjmBody* pbody, mjCFrame* frame) {
       }
 
       // create free joint without defaults
-      mjCJoint* pjoint = (mjCJoint*)mjm_addFreeJoint(pbody);
+      mjmJoint* pjoint = mjm_addFreeJoint(pbody);
-      pjoint->SetFrame(frame);
+      mjm_setFrame(pjoint->element, frame);
 
       // save defaults after creation, to make sure writing is ok
-      pjoint->def = def;
+      mjm_setDefault(pjoint->element, def);
 
       // read attributes
-      ReadAttrTxt(elem, "name", pjoint->name);
+      std::string name;
+      if (ReadAttrTxt(elem, "name", name)) {
+        mjm_setString(pjoint->name, name.c_str());
+      }
       ReadAttrInt(elem, "group", &pjoint->group);
     }
 
@@ -3102,17 +3140,17 @@ void mjXReader::Body(XMLElement* section, mjmBody* pbody, mjCFrame* frame) {
     // camera sub-element
     else if (name=="camera") {
       // create camera and parse
-      mjCCamera* pcam = (mjCCamera*)mjm_addCamera(pbody, def);
+      mjmCamera* pcam = mjm_addCamera(pbody, def);
       OneCamera(elem, pcam);
-      pcam->SetFrame(frame);
+      mjm_setFrame(pcam->element, frame);
     }
 
     // light sub-element
     else if (name=="light") {
       // create light and parse
-      mjCLight* plight = (mjCLight*)mjm_addLight(pbody, def);
+      mjmLight* plight = mjm_addLight(pbody, def);
       OneLight(elem, plight);
-      plight->SetFrame(frame);
+      mjm_setFrame(plight->element, frame);
     }
 
     // plugin sub-element
@@ -3162,10 +3200,12 @@ void mjXReader::Body(XMLElement* section, mjmBody* pbody, mjCFrame* frame) {
 
       // read attributes
       std::string name, childclass;
-      ReadAttrTxt(elem, "name", name);
+      if (ReadAttrTxt(elem, "name", name)) {
-      mjm_setString(pchild->name, name.c_str());
+        mjm_setString(pchild->name, name.c_str());
-      ReadAttrTxt(elem, "childclass", childclass);
+      }
-      mjm_setString(pchild->classname, childclass.c_str());
+      if (ReadAttrTxt(elem, "childclass", childclass)) {
+        mjm_setString(pchild->classname, childclass.c_str());
+      }
       ReadAttr(elem, "pos", 3, pchild->pos, text);
       ReadQuat(elem, "quat", pchild->quat, text);
       if (MapValue(elem, "mocap", &n, bool_map, 2)) {

src/xml/xml_native_reader.h

@@ -57,11 +57,11 @@ class mjXReader : public mjXBase {
   void OneMesh(tinyxml2::XMLElement* elem, mjCMesh* pmesh);
   void OneSkin(tinyxml2::XMLElement* elem, mjCSkin* pskin);
   void OneMaterial(tinyxml2::XMLElement* elem, mjCMaterial* pmaterial);
-  void OneJoint(tinyxml2::XMLElement* elem, mjCJoint* pjoint);
+  void OneJoint(tinyxml2::XMLElement* elem, mjmJoint* pjoint);
   void OneGeom(tinyxml2::XMLElement* elem, mjmGeom* pgeom);
   void OneSite(tinyxml2::XMLElement* elem, mjmSite& site);
-  void OneCamera(tinyxml2::XMLElement* elem, mjCCamera* pcamera);
+  void OneCamera(tinyxml2::XMLElement* elem, mjmCamera* pcamera);
-  void OneLight(tinyxml2::XMLElement* elem, mjCLight* plight);
+  void OneLight(tinyxml2::XMLElement* elem, mjmLight* plight);
   void OnePair(tinyxml2::XMLElement* elem, mjCPair* ppair);
   void OneEquality(tinyxml2::XMLElement* elem, mjCEquality* pequality);
   void OneTendon(tinyxml2::XMLElement* elem, mjCTendon* ptendon);

src/xml/xml_native_writer.cc

@@ -322,9 +322,9 @@ void mjXWriter::OneJoint(XMLElement* elem, mjCJoint* pjoint, mjCDef* def) {
 
   // userdata
   if (writingdefaults) {
-    WriteVector(elem, "user", pjoint->userdata);
+    WriteVector(elem, "user", pjoint->get_userdata());
   } else {
-    WriteVector(elem, "user", pjoint->userdata, def->joint.userdata);
+    WriteVector(elem, "user", pjoint->get_userdata(), def->joint.get_userdata());
   }
 }
 
@@ -468,7 +468,7 @@ void mjXWriter::OneCamera(XMLElement* elem, mjCCamera* pcam, mjCDef* def) {
   if (!writingdefaults) {
     WriteAttrTxt(elem, "name", pcam->name);
     WriteAttrTxt(elem, "class", pcam->classname);
-    WriteAttrTxt(elem, "target", pcam->targetbody);
+    WriteAttrTxt(elem, "target", pcam->get_targetbody());
     WriteAttr(elem, "pos", 3, pcam->pos);
     WriteAttr(elem, "quat", 4, pcam->quat, unitq);
   }
@@ -494,9 +494,9 @@ void mjXWriter::OneCamera(XMLElement* elem, mjCCamera* pcam, mjCDef* def) {
 
   // userdata
   if (writingdefaults) {
-    WriteVector(elem, "user", pcam->userdata);
+    WriteVector(elem, "user", pcam->get_userdata());
   } else {
-    WriteVector(elem, "user", pcam->userdata, def->camera.userdata);
+    WriteVector(elem, "user", pcam->get_userdata(), def->camera.get_userdata());
   }
 }
 
@@ -508,7 +508,7 @@ void mjXWriter::OneLight(XMLElement* elem, mjCLight* plight, mjCDef* def) {
   if (!writingdefaults) {
     WriteAttrTxt(elem, "name", plight->name);
     WriteAttrTxt(elem, "class", plight->classname);
-    WriteAttrTxt(elem, "target", plight->targetbody);
+    WriteAttrTxt(elem, "target", plight->get_targetbody());
     WriteAttr(elem, "pos", 3, plight->pos);
     WriteAttr(elem, "dir", 3, plight->dir);
   }

src/xml/xml_urdf.cc

@@ -210,8 +210,8 @@ void mjXURDF::Parse(
       // add a free joint to allow motion of the body
       // if the mass is 0, assume the object is static
       if (!static_body && pbody->mass > 0) {
-        mjCJoint* pjoint = (mjCJoint*)mjm_addJoint(pbody, 0);
+        mjmJoint* pjoint = mjm_addJoint(pbody, 0);
-        pjoint->name = urName[i] + "_free_joint";
+        mjm_setString(pjoint->name, (urName[i] + "_free_joint").c_str());
         pjoint->type = mjJNT_FREE;
       }
     }
@@ -371,7 +371,7 @@ void mjXURDF::Joint(XMLElement* joint_elem) {
   std::string jntname, name, text;
   XMLElement *elem;
   mjmBody *pbody, *parent, *world;
-  mjCJoint *pjoint=0, *pjoint1=0, *pjoint2=0;
+  mjmJoint *pjoint=0, *pjoint1=0, *pjoint2=0;
   int jointtype;
 
   // get type and name
@@ -414,16 +414,16 @@ void mjXURDF::Joint(XMLElement* joint_elem) {
   switch (jointtype) {
   case 0:     // revolute
   case 1:     // continuous
-    pjoint = (mjCJoint*)mjm_addJoint(pbody, 0);
+    pjoint = mjm_addJoint(pbody, 0);
-    pjoint->name = jntname;
+    mjm_setString(pjoint->name, jntname.c_str());
     pjoint->type = mjJNT_HINGE;
     mjuu_setvec(pjoint->pos, 0, 0, 0);
     mjuu_copyvec(pjoint->axis, axis, 3);
     break;
 
   case 2:     // prismatic
-    pjoint = (mjCJoint*)mjm_addJoint(pbody, 0);
+    pjoint = mjm_addJoint(pbody, 0);
-    pjoint->name = jntname;
+    mjm_setString(pjoint->name, jntname.c_str());
     pjoint->type = mjJNT_SLIDE;
     mjuu_setvec(pjoint->pos, 0, 0, 0);
     mjuu_copyvec(pjoint->axis, axis, 3);
@@ -433,8 +433,8 @@ void mjXURDF::Joint(XMLElement* joint_elem) {
     return;
 
   case 4:     // floating
-    pjoint = (mjCJoint*)mjm_addJoint(pbody, 0);
+    pjoint = mjm_addJoint(pbody, 0);
-    pjoint->name = jntname;
+    mjm_setString(pjoint->name, jntname.c_str());
     pjoint->type = mjJNT_FREE;
     break;
 
@@ -444,8 +444,8 @@ void mjXURDF::Joint(XMLElement* joint_elem) {
     mjuu_quat2mat(mat, quat);
 
     // construct slider along x
-    pjoint = (mjCJoint*)mjm_addJoint(pbody, 0);
+    pjoint = mjm_addJoint(pbody, 0);
-    pjoint->name = jntname + "_TX";
+    mjm_setString(pjoint->name, (jntname + "_TX").c_str());
     pjoint->type = mjJNT_SLIDE;
     tmpaxis[0] = mat[0];
     tmpaxis[1] = mat[3];
@@ -454,8 +454,8 @@ void mjXURDF::Joint(XMLElement* joint_elem) {
     mjuu_copyvec(pjoint->axis, tmpaxis, 3);
 
     // construct slider along y
-    pjoint1 = (mjCJoint*)mjm_addJoint(pbody, 0);
+    pjoint1 = mjm_addJoint(pbody, 0);
-    pjoint1->name = jntname + "_TY";
+    mjm_setString(pjoint1->name, (jntname + "_TY").c_str());
     pjoint1->type = mjJNT_SLIDE;
     tmpaxis[0] = mat[1];
     tmpaxis[1] = mat[4];
@@ -464,8 +464,8 @@ void mjXURDF::Joint(XMLElement* joint_elem) {
     mjuu_copyvec(pjoint1->axis, tmpaxis, 3);
 
     // construct hinge around z = locaxis
-    pjoint2 = (mjCJoint*)mjm_addJoint(pbody, 0);
+    pjoint2 = mjm_addJoint(pbody, 0);
-    pjoint2->name = jntname + "_RZ";
+    mjm_setString(pjoint2->name, (jntname + "_RZ").c_str());
     pjoint2->type = mjJNT_HINGE;
     mjuu_setvec(pjoint2->pos, 0, 0, 0);
     mjuu_copyvec(pjoint2->axis, axis, 3);