Set all flex edges to rigid when the flex is rigid.

PiperOrigin-RevId: 629740153
Change-Id: Ib2fb6f64e3d160268d2521d63830f41e44d03b20

src/user/user_flexcomp.cc

@@ -408,6 +408,9 @@ bool mjCFlexcomp::Make(mjSpec* spec, 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());
+  if (!centered) {
+    mjs_setDouble(pf->vert, point.data(), point.size());
+  }
 
   // rigid: set parent name, nothing else to do
   if (rigid) {

src/user/user_model.cc

@@ -2372,10 +2372,14 @@ void mjCModel::CopyObjects(mjModel* m) {
       m->flex_edge[2*(edge_adr+k)] = pfl->edge[k].first;
       m->flex_edge[2*(edge_adr+k)+1] = pfl->edge[k].second;
 
-      // check if vertex body weldids are the same
-      int b1 = pfl->vertbodyid[pfl->edge[k].first];
-      int b2 = pfl->vertbodyid[pfl->edge[k].second];
-      m->flexedge_rigid[edge_adr+k] = (bodies[b1]->weldid == bodies[b2]->weldid);
+      if (pfl->rigid) {
+        m->flexedge_rigid[edge_adr+k] = 1;
+      } else {
+        // check if vertex body weldids are the same
+        int b1 = pfl->vertbodyid[pfl->edge[k].first];
+        int b2 = pfl->vertbodyid[pfl->edge[k].second];
+        m->flexedge_rigid[edge_adr+k] = (bodies[b1]->weldid == bodies[b2]->weldid);
+      }
     }
 
     // advance counters