Copy texture coordinates from OBJ into flex. Fixes #2464.

PiperOrigin-RevId: 732109960
Change-Id: I506b3540ab5d489ce8f10d0c473919611ccb654a

src/user/user_flexcomp.cc

@@ -413,6 +413,7 @@ bool mjCFlexcomp::Make(mjsBody* body, char* error, int error_sz) {
   mjs_setString(pf->name, name.c_str());
   mjs_setInt(pf->elem, element.data(), element.size());
   mjs_setFloat(pf->texcoord, texcoord.data(), texcoord.size());
+  mjs_setInt(pf->facetexcoord, facetexcoord.data(), facetexcoord.size());
   if (!centered) {
     mjs_setDouble(pf->vert, point.data(), point.size());
   }
@@ -1055,6 +1056,11 @@ bool mjCFlexcomp::MakeMesh(mjCModel* model, char* error, int error_sz) {
     point[i] = (double) mesh.Vert(i);
   }
 
+  if (mesh.HasTexcoord()) {
+    texcoord = mesh.Texcoord();
+    facetexcoord = mesh.FaceTexcoord();
+  }
+
   // copy faces or create 3D mesh
   if (def.spec.flex->dim == 2) {
     element = mesh.Face();

src/user/user_flexcomp.h

@@ -106,6 +106,7 @@ class mjCFlexcomp {
   std::vector<bool> used;         // is point used by any element (false: skip)
   std::vector<int> element;       // flex elements
   std::vector<float> texcoord;    // vertex texture coordinates
+  std::vector<int> facetexcoord;  // face texture coordinates (OBJ only)
 
   // plugin support
   std::string plugin_name;

src/user/user_mesh.cc

@@ -3184,6 +3184,7 @@ void mjCFlex::PointToLocal() {
   spec.vert = &spec_vert_;
   spec.node = &spec_node_;
   spec.texcoord = &spec_texcoord_;
+  spec.facetexcoord = &spec_facetexcoord_;
   spec.elem = &spec_elem_;
   spec.info = &info;
   material = nullptr;
@@ -3192,6 +3193,7 @@ void mjCFlex::PointToLocal() {
   vert = nullptr;
   node = nullptr;
   texcoord = nullptr;
+  facetexcoord = nullptr;
   elem = nullptr;
 }
 
@@ -3217,6 +3219,7 @@ void mjCFlex::CopyFromSpec() {
   vert_ = spec_vert_;
   node_ = spec_node_;
   texcoord_ = spec_texcoord_;
+  facetexcoord_ = spec_facetexcoord_;
   elem_ = spec_elem_;
 
   // clear precompiled asset. TODO: use asset cache
@@ -3320,10 +3323,16 @@ void mjCFlex::Compile(const mjVFS* vfs) {
   }
 
   // check texcoord
-  if (!texcoord_.empty() && texcoord_.size()!=2*nvert) {
+  if (!texcoord_.empty() && texcoord_.size()!=2*nvert && facetexcoord_.empty()) {
     throw mjCError(this, "two texture coordinates per vertex expected");
   }
 
+  // no facetexcoord: copy from faces
+  if (facetexcoord_.empty() && !texcoord_.empty()) {
+    facetexcoord_.assign(3*nelem, 0);
+    memcpy(facetexcoord_.data(), elem_.data(), 3*nelem*sizeof(int));
+  }
+
   // resolve material name
   mjCBase* pmat = model->FindObject(mjOBJ_MATERIAL, material_);
   if (pmat) {

src/user/user_model.cc

@@ -2911,10 +2911,13 @@ void mjCModel::CopyObjects(mjModel* m) {
     }
     if (pfl->texcoord_.empty()) {
       m->flex_texcoordadr[i] = -1;
+      memcpy(m->flex_elemtexcoord + elemdata_adr, pfl->elem_.data(), pfl->elem_.size()*sizeof(int));
     } else {
       m->flex_texcoordadr[i] = texcoord_adr;
       memcpy(m->flex_texcoord + 2*texcoord_adr,
             pfl->texcoord_.data(), pfl->texcoord_.size()*sizeof(float));
+      memcpy(m->flex_elemtexcoord + elemdata_adr, pfl->facetexcoord_.data(),
+             pfl->facetexcoord_.size()*sizeof(int));
     }
     m->flex_elemnum[i] = pfl->nelem;
     memcpy(m->flex_elem + elemdata_adr, pfl->elem_.data(), pfl->elem_.size()*sizeof(int));

src/user/user_objects.h

@@ -776,6 +776,7 @@ class mjCFlex_ : public mjCBase {
   std::vector<double> node_;              // node positions
   std::vector<int> elem_;                 // element vertex ids
   std::vector<float> texcoord_;           // vertex texture coordinates
+  std::vector<int> facetexcoord_;         // face texture coordinates (OBJ only)
   std::string material_;                  // name of material used for rendering
 
   std::string spec_material_;
@@ -785,6 +786,7 @@ class mjCFlex_ : public mjCBase {
   std::vector<double> spec_node_;
   std::vector<int> spec_elem_;
   std::vector<float> spec_texcoord_;
+  std::vector<int> spec_facetexcoord_;
 };
 
 class mjCFlex: public mjCFlex_, private mjsFlex {
@@ -815,6 +817,7 @@ class mjCFlex: public mjCFlex_, private mjsFlex {
   const std::vector<double>& get_elemaabb() const { return elemaabb_; }
   const std::vector<int>& get_elem() const { return elem_; }
   const std::vector<float>& get_texcoord() const { return texcoord_; }
+  const std::vector<int>& get_facetexcoord() const { return facetexcoord_; }
   const std::vector<std::string>& get_nodebody() const { return nodebody_; }
 
   bool HasTexcoord() const;               // texcoord not null
@@ -927,6 +930,8 @@ class mjCMesh: public mjCMesh_, private mjsMesh {
   float Vert(int i) const { return vert_[i]; }
   const std::vector<float>& UserVert() const { return spec_vert_; }
   const std::vector<float>& UserNormal() const { return spec_normal_; }
+  const std::vector<float>& Texcoord() const { return texcoord_; }
+  const std::vector<int>& FaceTexcoord() const { return facetexcoord_; }
   const std::vector<float>& UserTexcoord() const { return spec_texcoord_; }
   const std::vector<int>& Face() const { return face_; }
   const std::vector<int>& UserFace() const { return spec_face_; }