Remove box, cylinder and ellipsoid composite types.

Also, fix a bug with Flex textures that was causing an incorrect allocation of the textures in mjModel. Fixes #2013.

PiperOrigin-RevId: 692510858
Change-Id: If781716216974e085244da27bc3aa57d91c3458c

doc/XMLreference.rst

@@ -3566,9 +3566,10 @@ saving the XML:
 
 :at:`texcoord`: :at-val:`real(2*npoint), optional`
    Texture coordinates of each point, passed through to the automatically-generated flex. Note that flexcomp does not
-   generate texture coordinates automatically, except for 2D grids. For all other types, the user can specify explicit
+   generate texture coordinates automatically, except for 2D grids, box, cylinder and ellipsoid. For all other types,
-   texture coordinates here, even if the points themselves were generated automatically. This requires understanding of
+   the user can specify explicit texture coordinates here, even if the points themselves were generated automatically.
-   the layout of the automatically-generated points and how they correspond to the texture referenced by the material.
+   This requires understanding of the layout of the automatically-generated points and how they correspond to the
+   texture referenced by the material.
 
 .. _body-flexcomp-mass:
 

doc/changelog.rst

@@ -17,6 +17,8 @@ General
 - Sorting now uses a faster, native sort function (fixes :github:issue:`1638`).
 - The PBR texture layers introduced in 3.2.1 were refactored from seperate sub-elements to a single
   :ref:`layer<material-layer>` sub-element.
+- The composite types box, cylinder, and sphere have been removed. Users should instead use the equivalent types
+  available in :ref:`flexcomp<body-flexcomp>`.
 
 MJX
 ^^^
@@ -33,6 +35,7 @@ Bug fixes
   several places leading to incorrect computations of constraint inertia, readings of affected force/torque sensors and
   runtime enabling/disabling of such constraints.
 - Fixed a bug in slider-crank :ref:`transmission<geTransmission>`. The bug was introduced in 3.0.0.
+- Fixed a bug in flex texture coordinates that prevented the correct allocation of textures in mjModel.
 
 
 Documentation

doc/modeling.rst

@@ -1280,62 +1280,11 @@ scenario (e.g. a stretched rubber band).
 The cloth is deprecated. It is recommended to use 2D flex :ref:`deformable objects <CDeformable>` for simulating thin
 elastic structures.
 
-**Box**.
+**Box, cylinder and ellipsoid**.
 
-|image14| |image15|
 
-.. code-block:: xml
+The box type, as well as the cylinder and ellipsoid types, are now deprecated in favor of 3D flex :ref:`deformable
-
+objects <CDeformable>``. element.
-   <body pos="0 0 1">
-     <freejoint/>
-     <composite type="box" count="7 7 7" spacing="0.04">
-       <skin texcoord="true" material="matsponge" rgba=".7 .7 .7 1"/>
-       <geom type="capsule" size=".015 0.05" rgba=".8 .2 .1 1"/>
-     </composite>
-   </body>
-
-The box type, as well as the cylinder and ellipsoid types below, are used to model soft 3D objects. The element bodies
-form a grid along the outer shell, thus the number of element bodies scales with the square of the linear dimension.
-This is much more efficient than simulating a 3D grid. The parent body within which :el:`composite` appears is at the
-center of the soft object. All element bodies are children of the parent. Each element body has a single sliding joint
-pointing away from the parent. These joints allow the surface of the soft object to compress and expand at any point.
-The joints are equality-constrained to their initial position, so as to maintain the shape. In addition each joint is
-equality-constrained to its neighbor joints, so that when the soft objects deforms, the deformation is smooth.
-Finally, there is a tendon equality constraint specifying that the sum of all joints should remain constant. This
-attempts to preserve the volume of the soft object approximately. If the object is squeezed from all sides it will
-compress and the volume will decrease, but otherwise some element bodies will stick out to compensate for squeezing
-elsewhere. The plot on the left shows this effect; we are using the capsule probe to compress one corner, and the
-opposite sides of the cube expand a bit, while the deformations remain smooth. The :at:`count` attribute determines
-the number of element bodies in each dimension, so if the counts are different the resulting object will be a
-rectangular box and not a cube. The geoms attached to the element bodies can be spheres, capsules or ellipsoids.
-Spheres are faster for collision detection, but they result in a thin shell, allowing other bodies to "get under the
-skin" of the soft object. When capsules or ellipsoids are used, they are automatically oriented so that the long axis
-points to the outside, thus creating a thicker shell which is harder to penetrate.
-
-**Cylinder and ellipsoid**.
-
-|image16| |image17|
-
-.. code-block:: xml
-
-   <body pos="0 0 1">
-     <freejoint/>
-     <composite type="ellipsoid" count="5 7 9" spacing="0.05">
-       <skin texcoord="true" material="matsponge" rgba=".7 .7 .7 1"/>
-       <geom type="capsule" size=".015 0.05" rgba=".8 .2 .1 1"/>
-     </composite>
-   </body>
-
-Cylinders and ellipsoids are created in the same way as boxes. The only difference is that the reference positions of
-the element bodies (relative to the parent) are projected on a cylinder or ellipsoid, with size implied by the
-:at:`count` attribute. The automatic skin generator is aware of the smooth surfaces, and adjusts the skin normals
-accordingly. In the plots we have used the capsule probe to press on each body, then paused the simulation and moved the
-probe away (which is possible because the probe is a mocap body which can move independent of the physics). In this way
-we can see the indentation made by the probe, and the resulting deformation in the rest of the body. By changing the
-solref and solimp attributes of the equality constraints that hold the soft object together, one can adjust the behavior
-of the system making it softer or harder, damped or springy, etc. Note that box, cylinder and ellipsoid objects do not
-involve long kinematic chains, and can be simulated at large timesteps -- similar to particle and grid, and unlike rope
-and cloth.
 
 .. _CDeformable:
 

model/composite/softbox.xml

@@ -14,10 +14,6 @@
 -->
 
 <mujoco model="Soft box">
-<!-- Degree of Freedom: 224
-     Actuators: 0
-     Equality constraints: 651
--->
   <include file="scene.xml"/>
 
   <option solver="CG" tolerance="1e-6"/>
@@ -25,13 +21,14 @@
   <size memory="30M"/>
 
   <worldbody>
-    <body pos="0 0 1">
+    <body pos="0 0 1" name="body">
       <freejoint/>
-      <composite type="box" count="7 7 7" spacing="0.04">
+      <geom size=".1" contype="0" conaffinity="0" group="4"/>
-        <skin texcoord="true" material="matsponge" rgba=".7 .7 .7 1"/>
+      <flexcomp name="softbox" type="box" count="7 7 7" spacing=".04 .04 .04"
-        <geom type="capsule" size=".015 0.05" rgba=".8 .2 .1 1"/>
+                radius="0.01" dim="3" material="matsponge">
-        <joint kind="main" solreffix="0.03 1" solimpfix="0 .1 .01"/>
+        <contact internal="false" selfcollide="none"/>
-      </composite>
+        <edge equality="true"/>
+      </flexcomp>
     </body>
   </worldbody>
 </mujoco>

src/user/user_composite.cc

@@ -192,25 +192,6 @@ void mjCComposite::SetDefault(void) {
   case mjCOMPTYPE_CLOTH:          // cloth
     break;
 
-  case mjCOMPTYPE_BOX:            // 3D
-  case mjCOMPTYPE_CYLINDER:
-  case mjCOMPTYPE_ELLIPSOID:
-
-    // no self-collisions
-    def[0].spec.geom->contype = 0;
-
-    // soft smoothing
-    AdjustSoft(solrefsmooth, solimpsmooth, 1);
-
-    // soft fix everywhere
-    for (int i=0; i<mjNCOMPKINDS; i++) {
-      AdjustSoft(def[i].spec.equality->solref, def[i].spec.equality->solimp, 1);
-    }
-
-    // hard main tendon fix
-    AdjustSoft(def[mjCOMPKIND_TENDON].spec.equality->solref,
-               def[mjCOMPKIND_TENDON].spec.equality->solimp, 0);
-    break;
   default:
     // SHOULD NOT OCCUR
     mju_error("Invalid composite type: %d", type);
@@ -347,11 +328,6 @@ bool mjCComposite::Make(mjSpec* spec, mjsBody* body, char* error, int error_sz)
                    "\"shell\" instead.",
                    error_sz);
 
-  case mjCOMPTYPE_BOX:
-  case mjCOMPTYPE_CYLINDER:
-  case mjCOMPTYPE_ELLIPSOID:
-    return MakeBox(model, body, error, error_sz);
-
   default:
     return comperr(error, "Unknown shape in composite", error_sz);
   }
@@ -919,166 +895,6 @@ mjsBody* mjCComposite::AddRopeBody(mjCModel* model, mjsBody* body, int ix, int i
 
 
 
-// project from box to other shape
-void mjCComposite::BoxProject(double* pos) {
-  // determine sizes
-  double size[3] = {
-    0.5*spacing*(count[0]-1),
-    0.5*spacing*(count[1]-1),
-    0.5*spacing*(count[2]-1)
-  };
-
-  // box
-  if (type==mjCOMPTYPE_BOX) {
-    pos[0] *= size[0];
-    pos[1] *= size[1];
-    pos[2] *= size[2];
-  }
-
-  // cylinder
-  else if (type==mjCOMPTYPE_CYLINDER) {
-    double L0 = std::max(std::abs(pos[0]), std::abs(pos[1]));
-    mjuu_normvec(pos, 2);
-    pos[0] *= size[0]*L0;
-    pos[1] *= size[1]*L0;
-    pos[2] *= size[2];
-  }
-
-  // ellipsoid
-  else if (type==mjCOMPTYPE_ELLIPSOID) {
-    mjuu_normvec(pos, 3);
-    pos[0] *= size[0];
-    pos[1] *= size[1];
-    pos[2] *= size[2];
-  }
-}
-
-
-
-// make 3d box, ellipsoid or cylinder
-bool mjCComposite::MakeBox(mjCModel* model, mjsBody* body, char* error, int error_sz) {
-  char txt[100];
-
-  // check dim
-  if (dim!=3) {
-    return comperr(error, "Box and ellipsoid must be three-dimensional", error_sz);
-  }
-
-  // center geom: two times bigger
-  mjsGeom* geom = mjs_addGeom(body, &def[0].spec);
-  mjs_setDefault(geom->element, mjs_getDefault(body->element));
-  geom->type = mjGEOM_SPHERE;
-  mju::sprintf_arr(txt, "%sGcenter", prefix.c_str());
-  mjs_setString(geom->name, txt);
-  mjuu_setvec(geom->pos, 0, 0, 0);
-  geom->size[0] *= 2;
-  geom->size[1] = 0;
-  geom->size[2] = 0;
-
-  // fixed tendon for all joints
-  mjCTendon* ten = model->AddTendon(def + mjCOMPKIND_TENDON);
-  ten->classname = model->Default()->name;
-  mju::sprintf_arr(txt, "%sT", prefix.c_str());
-  ten->name = txt;
-
-  // create bodies, geoms and joints: outside shell only
-  for (int ix=0; ix<count[0]; ix++) {
-    for (int iy=0; iy<count[1]; iy++) {
-      for (int iz=0; iz<count[2]; iz++) {
-        if (ix==0 || ix==count[0]-1 ||
-            iy==0 || iy==count[1]-1 ||
-            iz==0 || iz==count[2]-1) {
-          // create body
-          mjsBody* b = mjs_addBody(body, NULL);
-          mju::sprintf_arr(txt, "%sB%d_%d_%d", prefix.c_str(), ix, iy, iz);
-          mjs_setString(b->name, txt);
-
-          // set body position (+/- 1)
-          b->pos[0] = 2.0*ix/(count[0]-1) - 1;
-          b->pos[1] = 2.0*iy/(count[1]-1) - 1;
-          b->pos[2] = 2.0*iz/(count[2]-1) - 1;
-
-          // reshape
-          BoxProject(b->pos);
-
-          // reorient body
-          b->alt.type = mjORIENTATION_ZAXIS;
-          mjuu_copyvec(b->alt.zaxis, b->pos, 3);
-          mjuu_normvec(b->alt.zaxis, 3);
-
-          // add geom
-          mjsGeom* g = mjs_addGeom(b, &def[0].spec);
-          mjs_setDefault(g->element, mjs_getDefault(body->element));
-          mju::sprintf_arr(txt, "%sG%d_%d_%d", prefix.c_str(), ix, iy, iz);
-          mjs_setString(g->name, txt);
-
-          // offset inwards, enforce sphere or capsule
-          if (g->type==mjGEOM_CAPSULE) {
-            g->pos[2] = -(g->size[0] + g->size[1]);
-          } else {
-            g->type = mjGEOM_SPHERE;
-            g->pos[2] = -g->size[0];
-          }
-
-          // add slider joint
-          mjsJoint* jnt = mjs_addJoint(b, &defjoint[mjCOMPKIND_JOINT][0].spec);
-          mjs_setDefault(jnt->element, mjs_getDefault(body->element));
-          mju::sprintf_arr(txt, "%sJ%d_%d_%d", prefix.c_str(), ix, iy, iz);
-          mjs_setString(jnt->name, txt);
-          jnt->type = mjJNT_SLIDE;
-          mjuu_setvec(jnt->pos, 0, 0, 0);
-          mjuu_setvec(jnt->axis, 0, 0, 1);
-
-          // add fix constraint
-          mjsEquality* eq = mjs_addEquality(&model->spec, &def[mjCOMPKIND_JOINT].spec);
-          mjs_setDefault(eq->element,  &model->Default()->spec);
-          eq->type = mjEQ_JOINT;
-          mjs_setString(eq->name1, mjs_getString(jnt->name));
-
-          // add joint to tendon
-          ten->WrapJoint(std::string(mjs_getString(jnt->name)), 1);
-
-          // add neighbor constraints
-          for (int i=0; i<3; i++) {
-            int ix1 = mjMIN(ix+(i==0), count[0]-1);
-            int iy1 = mjMIN(iy+(i==1), count[1]-1);
-            int iz1 = mjMIN(iz+(i==2), count[2]-1);
-            if ((ix1==0 || ix1==count[0]-1 ||
-                 iy1==0 || iy1==count[1]-1 ||
-                 iz1==0 || iz1==count[2]-1) &&
-                (ix!=ix1 || iy!=iy1 || iz!=iz1)) {
-              char txt2[200];
-              mju::sprintf_arr(txt2,
-                               "%sJ%d_%d_%d", prefix.c_str(), ix1, iy1, iz1);
-              mjsEquality* eqn = mjs_addEquality(&model->spec, 0);
-              mju_copy(eqn->solref, solrefsmooth, mjNREF);
-              mju_copy(eqn->solimp, solimpsmooth, mjNIMP);
-              eqn->type = mjEQ_JOINT;
-              mjs_setString(eqn->name1, txt);
-              mjs_setString(eqn->name2, txt2);
-            }
-          }
-        }
-      }
-    }
-  }
-
-  // finalize fixed tendon
-  mjsEquality* eqt = mjs_addEquality(&model->spec, &def[mjCOMPKIND_TENDON].spec);
-  mjs_setDefault(eqt->element, &model->Default()->spec);
-  eqt->type = mjEQ_TENDON;
-  mjs_setString(eqt->name1, ten->name.c_str());
-
-  // skin
-  if (skin) {
-    MakeSkin3(model);
-  }
-
-  return true;
-}
-
-
-
 // add shear tendons to 2D
 void mjCComposite::MakeShear(mjCModel* model) {
   char txt[100], txt1[100], txt2[100];
@@ -1838,272 +1654,3 @@ void mjCComposite::MakeSkin2Subgrid(mjCModel* model, mjtNum inflate) {
   mju_free(D);
 }
 
-
-
-// add skin to 3D
-void mjCComposite::MakeSkin3(mjCModel* model) {
-  int vcnt = 0;
-  std::map<std::string, int> vmap;
-  char txt[100], cnt0[10], cnt1[10], cnt2[10];
-  std::string fmt;
-
-  // string counts
-  mju::sprintf_arr(cnt0, "%d", count[0]-1);
-  mju::sprintf_arr(cnt1, "%d", count[1]-1);
-  mju::sprintf_arr(cnt2, "%d", count[2]-1);
-
-  // add skin, set name and material
-  mjsSkin* skin = mjs_addSkin(&model->spec);
-  mju::sprintf_arr(txt, "%sSkin", prefix.c_str());
-  mjs_setString(skin->name, txt);
-  mjs_setString(skin->material, skinmaterial.c_str());
-  mjuu_copyvec(skin->rgba, skinrgba, 4);
-  skin->inflate = skininflate;
-  skin->group = skingroup;
-
-  // box
-  if (type==mjCOMPTYPE_BOX || type==mjCOMPTYPE_PARTICLE) {
-    // z-faces
-    MakeSkin3Box(skin, count[0], count[1], 1, vcnt, "%sB%d_%d_0");
-    fmt = "%sB%d_%d_" + std::string(cnt2);
-    MakeSkin3Box(skin, count[0], count[1], 0, vcnt, fmt.c_str());
-
-    // y-faces
-    MakeSkin3Box(skin, count[0], count[2], 0, vcnt, "%sB%d_0_%d");
-    fmt = "%sB%d_" + std::string(cnt1) + "_%d";
-    MakeSkin3Box(skin, count[0], count[2], 1, vcnt, fmt.c_str());
-
-    // x-faces
-    MakeSkin3Box(skin, count[1], count[2], 1, vcnt, "%sB0_%d_%d");
-    fmt = "%sB" + std::string(cnt0) + "_%d_%d";
-    MakeSkin3Box(skin, count[1], count[2], 0, vcnt, fmt.c_str());
-  }
-
-  // cylinder
-  else if (type==mjCOMPTYPE_CYLINDER) {
-    // generate vertices in map
-    for (int ix=0; ix<count[0]; ix++) {
-      for (int iy=0; iy<count[1]; iy++) {
-        for (int iz=0; iz<count[2]; iz++) {
-          bool xedge = (ix==0 || ix==count[0]-1);
-          bool yedge = (iy==0 || iy==count[1]-1);
-          if (xedge || yedge) {
-            // body name
-            mju::sprintf_arr(txt, "%sB%d_%d_%d", prefix.c_str(), ix, iy, iz);
-
-            // add vertex
-            vert.push_back(0);
-            vert.push_back(0);
-            vert.push_back(0);
-
-            // texture coordinate
-            if (skintexcoord) {
-              float X = 0, Y = 0;
-              if (xedge) {
-                X = iy/(float)(count[1]-1);
-                Y = iz/(float)(count[2]-1);
-              } else {
-                X = ix/(float)(count[0]-1);
-                Y = iz/(float)(count[2]-1);
-              }
-
-              texcoord.push_back(X);
-              texcoord.push_back(Y);
-            }
-
-            // save vertex id in map
-            vmap[txt] = vcnt;
-            vcnt++;
-          }
-        }
-      }
-    }
-
-    // y-faces
-    MakeSkin3Smooth(skin, count[0], count[2], 0, vmap, "%sB%d_0_%d");
-    fmt = "%sB%d_" + std::string(cnt1) + "_%d";
-    MakeSkin3Smooth(skin, count[0], count[2], 1, vmap, fmt.c_str());
-
-    // x-faces
-    MakeSkin3Smooth(skin, count[1], count[2], 1, vmap, "%sB0_%d_%d");
-    fmt = "%sB" + std::string(cnt0) + "_%d_%d";
-    MakeSkin3Smooth(skin, count[1], count[2], 0, vmap, fmt.c_str());
-
-    // z-faces, boxy-type
-    MakeSkin3Box(skin, count[0], count[1], 1, vcnt, "%sB%d_%d_0");
-    fmt = "%sB%d_%d_" + std::string(cnt2);
-    MakeSkin3Box(skin, count[0], count[1], 0, vcnt, fmt.c_str());
-  }
-
-  // smooth
-  else {
-    // generate vertices in map
-    for (int ix=0; ix<count[0]; ix++) {
-      for (int iy=0; iy<count[1]; iy++) {
-        for (int iz=0; iz<count[2]; iz++) {
-          bool xedge = (ix==0 || ix==count[0]-1);
-          bool yedge = (iy==0 || iy==count[1]-1);
-          bool zedge = (iz==0 || iz==count[2]-1);
-          if (xedge || yedge || zedge) {
-            // body name
-            mju::sprintf_arr(txt, "%sB%d_%d_%d", prefix.c_str(), ix, iy, iz);
-
-            // add vertex
-            vert.push_back(0);
-            vert.push_back(0);
-            vert.push_back(0);
-
-            // texture coordinate
-            if (skintexcoord) {
-              float X = 0, Y = 0;
-              if (xedge) {
-                X = iy/(float)(count[1]-1);
-                Y = iz/(float)(count[2]-1);
-              } else if (yedge) {
-                X = ix/(float)(count[0]-1);
-                Y = iz/(float)(count[2]-1);
-              } else {
-                X = ix/(float)(count[0]-1);
-                Y = iy/(float)(count[1]-1);
-              }
-
-              texcoord.push_back(X);
-              texcoord.push_back(Y);
-            }
-
-            // save vertex id in map
-            vmap[txt] = vcnt;
-            vcnt++;
-          }
-        }
-      }
-    }
-
-    // z-faces
-    MakeSkin3Smooth(skin, count[0], count[1], 1, vmap, "%sB%d_%d_0");
-    fmt = "%sB%d_%d_" + std::string(cnt2);
-    MakeSkin3Smooth(skin, count[0], count[1], 0, vmap, fmt.c_str());
-
-    // y-faces
-    MakeSkin3Smooth(skin, count[0], count[2], 0, vmap, "%sB%d_0_%d");
-    fmt = "%sB%d_" + std::string(cnt1) + "_%d";
-    MakeSkin3Smooth(skin, count[0], count[2], 1, vmap, fmt.c_str());
-
-    // x-faces
-    MakeSkin3Smooth(skin, count[1], count[2], 1, vmap, "%sB0_%d_%d");
-    fmt = "%sB" + std::string(cnt0) + "_%d_%d";
-    MakeSkin3Smooth(skin, count[1], count[2], 0, vmap, fmt.c_str());
-  }
-
-  CopyIntoSkin(skin);
-}
-
-
-
-// make one face of 3D skin, box
-void mjCComposite::MakeSkin3Box(mjsSkin* skin, int c0, int c1, int side,
-                                int& vcnt, const char* format) {
-  char txt[100];
-
-  // loop over bodies/vertices of specified face
-  for (int i0=0; i0<c0; i0++) {
-    for (int i1=0; i1<c1; i1++) {
-      // vertex
-      vert.push_back(0);
-      vert.push_back(0);
-      vert.push_back(0);
-
-      // texture coordinate
-      if (skintexcoord) {
-        texcoord.push_back(i0/(float)(c0-1));
-        texcoord.push_back(i1/(float)(c1-1));
-      }
-
-      // face
-      if (i0<c0-1 && i1<c1-1) {
-        face.push_back(vcnt + i0*c1+i1);
-        face.push_back(vcnt + (i0+1)*c1+i1+(side==1));
-        face.push_back(vcnt + (i0+1)*c1+i1+(side==0));
-
-        face.push_back(vcnt + i0*c1+i1);
-        face.push_back(vcnt + (i0+(side==0))*c1+i1+1);
-        face.push_back(vcnt + (i0+(side==1))*c1+i1+1);
-      }
-
-      // body name
-      mju::sprintf_arr(txt, format, prefix.c_str(), i0, i1);
-
-      // bind pose: origin
-      mjs_appendString(skin->bodyname, txt);
-      bindpos.push_back(0);
-      bindpos.push_back(0);
-      bindpos.push_back(0);
-      bindquat.push_back(1);
-      bindquat.push_back(0);
-      bindquat.push_back(0);
-      bindquat.push_back(0);
-
-      // vertid and vertweight
-      vertid.push_back({vcnt + i0*c1+i1});
-      vertweight.push_back({1});
-    }
-  }
-
-  // update vertex count
-  vcnt += c0*c1;
-}
-
-
-
-// make one face of 3D skin, smooth
-void mjCComposite::MakeSkin3Smooth(mjsSkin* skin, int c0, int c1, int side,
-                                   const std::map<std::string, int>& vmap,
-                                   const char* format) {
-  char txt00[100], txt01[100], txt10[100], txt11[100];
-
-  // loop over bodies/vertices of specified face
-  for (int i0=0; i0<c0; i0++) {
-    for (int i1=0; i1<c1; i1++) {
-      // body names
-      mju::sprintf_arr(txt00, format, prefix.c_str(), i0, i1);
-      mju::sprintf_arr(txt01, format, prefix.c_str(), i0, i1+1);
-      mju::sprintf_arr(txt10, format, prefix.c_str(), i0+1, i1);
-      mju::sprintf_arr(txt11, format, prefix.c_str(), i0+1, i1+1);
-
-      // face
-      if (i0<c0-1 && i1<c1-1) {
-        if (side==0) {
-          face.push_back(vmap.find(txt00)->second);
-          face.push_back(vmap.find(txt10)->second);
-          face.push_back(vmap.find(txt11)->second);
-
-          face.push_back(vmap.find(txt00)->second);
-          face.push_back(vmap.find(txt11)->second);
-          face.push_back(vmap.find(txt01)->second);
-        } else {
-          face.push_back(vmap.find(txt00)->second);
-          face.push_back(vmap.find(txt01)->second);
-          face.push_back(vmap.find(txt11)->second);
-
-          face.push_back(vmap.find(txt00)->second);
-          face.push_back(vmap.find(txt11)->second);
-          face.push_back(vmap.find(txt10)->second);
-        }
-      }
-
-      // bind pose: origin
-      mjs_appendString(skin->bodyname, txt00);
-      bindpos.push_back(0);
-      bindpos.push_back(0);
-      bindpos.push_back(0);
-      bindquat.push_back(1);
-      bindquat.push_back(0);
-      bindquat.push_back(0);
-      bindquat.push_back(0);
-
-      // vertid and vertweight
-      vertid.push_back({vmap.find(txt00)->second});
-      vertweight.push_back({1});
-    }
-  }
-}

src/user/user_composite.h

@@ -31,9 +31,6 @@ typedef enum _mjtCompType {
   mjCOMPTYPE_ROPE,
   mjCOMPTYPE_LOOP,
   mjCOMPTYPE_CLOTH,
-  mjCOMPTYPE_BOX,
-  mjCOMPTYPE_CYLINDER,
-  mjCOMPTYPE_ELLIPSOID,
 
   mjNCOMPTYPES
 } mjtCompType;
@@ -75,7 +72,6 @@ class mjCComposite {
   bool MakeGrid(mjCModel* model, mjsBody* body, char* error, int error_sz);
   bool MakeRope(mjCModel* model, mjsBody* body, char* error, int error_sz);
   bool MakeCable(mjCModel* model, mjsBody* body, char* error, int error_sz);
-  bool MakeBox(mjCModel* model, mjsBody* body, char* error, int error_sz);
   void MakeShear(mjCModel* model);
 
   void MakeSkin2(mjCModel* model, mjtNum inflate);
@@ -85,13 +81,6 @@ class mjCComposite {
   void MakeCableBones(mjCModel* model, mjsSkin* skin);
   void MakeCableBonesSubgrid(mjCModel* model, mjsSkin* skin);
 
-  void MakeSkin3(mjCModel* model);
-  void MakeSkin3Box(mjsSkin* skin, int c0, int c1, int side, int& vcnt, const char* format);
-  void MakeSkin3Smooth(mjsSkin* skin, int c0, int c1, int side,
-                       const std::map<std::string, int>& vmap, const char* format);
-
-  void BoxProject(double* pos);
-
   // common properties
   std::string prefix;             // name prefix
   mjtCompType type;               // composite type

src/user/user_flexcomp.cc

@@ -763,6 +763,7 @@ bool mjCFlexcomp::MakeSquare(char* error, int error_sz) {
 // make 3d box, ellipsoid or cylinder
 bool mjCFlexcomp::MakeBox(char* error, int error_sz) {
   double pos[3];
+  bool needtex = texcoord.empty() && !std::string(mjs_getString(def.spec.flex->material)).empty();
 
   // set 3D
   def.spec.flex->dim = 3;
@@ -772,6 +773,12 @@ bool mjCFlexcomp::MakeBox(char* error, int error_sz) {
   point.push_back(0);
   point.push_back(0);
 
+  // add texture coordinates, if not specified explicitly
+  if (needtex) {
+    texcoord.push_back(0);
+    texcoord.push_back(0);
+  }
+
   // iz=0/max
   for (int iz=0; iz < count[2]; iz+=count[2]-1) {
     for (int ix=0; ix < count[0]; ix++) {
@@ -782,6 +789,12 @@ bool mjCFlexcomp::MakeBox(char* error, int error_sz) {
         point.push_back(pos[1]);
         point.push_back(pos[2]);
 
+        // add texture coordinates, if not specified explicitly
+        if (needtex) {
+          texcoord.push_back(ix/(float)std::max(count[0]-1, 1));
+          texcoord.push_back(iy/(float)std::max(count[1]-1, 1));
+        }
+
         // add elements
         if (ix < count[0]-1 && iy < count[1]-1) {
           element.push_back(0);
@@ -808,6 +821,12 @@ bool mjCFlexcomp::MakeBox(char* error, int error_sz) {
           point.push_back(pos[0]);
           point.push_back(pos[1]);
           point.push_back(pos[2]);
+
+          // add texture coordinates
+          if (needtex) {
+            texcoord.push_back(ix/(float)std::max(count[0]-1, 1));
+            texcoord.push_back(iz/(float)std::max(count[2]-1, 1));
+          }
         }
 
         // add elements
@@ -836,6 +855,12 @@ bool mjCFlexcomp::MakeBox(char* error, int error_sz) {
           point.push_back(pos[0]);
           point.push_back(pos[1]);
           point.push_back(pos[2]);
+
+          // add texture coordinates
+          if (needtex) {
+            texcoord.push_back(iy/(float)std::max(count[1]-1, 1));
+            texcoord.push_back(iz/(float)std::max(count[2]-1, 1));
+          }
         }
 
         // add elements

src/user/user_model.cc

@@ -1613,6 +1613,7 @@ void mjCModel::SetSizes() {
     nflexelemedge += flexes_[i]->nelem * mjCFlex::kNumEdges[flexes_[i]->dim - 1];
     nflexshelldata += (int)flexes_[i]->shell.size();
     nflexevpair += (int)flexes_[i]->evpair.size()/2;
+    nflextexcoord += (flexes_[i]->HasTexcoord() ? flexes_[i]->get_texcoord().size()/2 : 0);
   }
 
   // mesh counts

src/xml/xml_native_reader.cc

@@ -742,10 +742,7 @@ const mjMap comp_map[mjNCOMPTYPES] = {
   {"rope",        mjCOMPTYPE_ROPE},
   {"loop",        mjCOMPTYPE_LOOP},
   {"cable",       mjCOMPTYPE_CABLE},
-  {"cloth",       mjCOMPTYPE_CLOTH},
+  {"cloth",       mjCOMPTYPE_CLOTH}
-  {"box",         mjCOMPTYPE_BOX},
-  {"cylinder",    mjCOMPTYPE_CYLINDER},
-  {"ellipsoid",   mjCOMPTYPE_ELLIPSOID}
 };
 
 

test/engine/testdata/skingroup.xml

@@ -27,17 +27,15 @@
       <geom type="box" size=".5 .5 .1"/>
     </body>
     <body pos="1 -1 .6">
-      <freejoint/>
+      <composite prefix="B0" type="grid" count="4 4 1" spacing=".2">
-      <composite prefix="B0" type="box" count="4 4 4" spacing=".2">
         <geom group="4" size=".1"/>
-        <skin rgba="1 1 0 1" group="2"/>
+        <skin rgba="1 1 0 1" group="2" inflate=".1"/>
       </composite>
     </body>
     <body pos="-1 1 .6">
-      <freejoint/>
+      <composite prefix="B1" type="grid" count="4 4 1" spacing=".2">
-      <composite prefix="B1" type="box" count="4 4 4" spacing=".2">
         <geom group="2" size=".1"/>
-        <skin rgba="0 1 1 1" group="4"/>
+        <skin rgba="0 1 1 1" group="4" inflate=".1"/>
       </composite>
     </body>
   </worldbody>

test/user/user_composite_test.cc

@@ -43,7 +43,7 @@ TEST_F(UserCompositeTest, MultipleJointsNotAllowedUnlessParticle) {
   <worldbody>
     <body>
       <freejoint/>
-      <composite type="box" count="7 7 7" spacing="0.04">
+      <composite type="grid" count="7 7 1" spacing="0.04">
         <joint kind="main" solreffix="0.03 1" solimpfix="0 .1 .01"/>
         <joint kind="main" solreffix="0.03 1" solimpfix="0 .1 .01"/>
       </composite>

test/xml/xml_native_reader_test.cc

@@ -1681,13 +1681,13 @@ TEST_F(XMLReaderTest, ReadsSkinGroups) {
   <mujoco>
     <worldbody>
       <body>
-        <composite prefix="B0" type="box" count="4 4 4" spacing=".2">
+        <composite prefix="B0" type="grid" count="4 4 1" spacing=".2">
           <geom size=".1" group="2"/>
           <skin group="4"/>
         </composite>
       </body>
       <body>
-        <composite prefix="B1" type="box" count="4 4 4" spacing=".2">
+        <composite prefix="B1" type="grid" count="4 4 1" spacing=".2">
           <geom size=".1" group="4"/>
           <skin group="2"/>
         </composite>
@@ -1698,8 +1698,8 @@ TEST_F(XMLReaderTest, ReadsSkinGroups) {
   std::array<char, 1024> error;
   mjModel* model = LoadModelFromString(xml, error.data(), error.size());
   ASSERT_THAT(model, NotNull());
-  int geomid1 = mj_name2id(model, mjOBJ_GEOM, "B0G0_0_0");
+  int geomid1 = mj_name2id(model, mjOBJ_GEOM, "B0G0_0");
-  int geomid2 = mj_name2id(model, mjOBJ_GEOM, "B1G0_0_0");
+  int geomid2 = mj_name2id(model, mjOBJ_GEOM, "B1G0_0");
   EXPECT_THAT(model->geom_group[geomid1], 2);
   EXPECT_THAT(model->skin_group[0], 4);
   EXPECT_THAT(model->geom_group[geomid2], 4);
@@ -1712,7 +1712,7 @@ TEST_F(XMLReaderTest, InvalidSkinGroup) {
   <mujoco>
     <worldbody>
       <body>
-        <composite prefix="B0" type="box" count="6 6 6" spacing=".2">
+        <composite prefix="B0" type="grid" count="6 6 1" spacing=".2">
           <geom size=".1"/>
           <skin group="6"/>
         </composite>