Add MeshCollisionAPI to collider Meshes with convexHull approximation.

PiperOrigin-RevId: 754014642 Change-Id: I44cff505a2b9b7120a38f8c896b2c6560ce51c43
2025-05-02 08:34:28 -07:00
parent ab63a7e824
commit 253abad210
2 changed files with 26 additions and 5 deletions
@@ -883,6 +883,21 @@ class ModelWriter {
                          model_->geom_conaffinity[geom_id] != 0)) {
      ApplyApiSchema(data_, geom_path,
                     pxr::UsdPhysicsTokens->PhysicsCollisionAPI);
+      // For meshes, also apply PhysicsMeshCollisionAPI and set the
+      // approximation attribute.
+      if (geom->type == mjGEOM_MESH) {
+        ApplyApiSchema(data_, geom_path,
+                       pxr::UsdPhysicsTokens->PhysicsMeshCollisionAPI);
+
+        // Note: MuJoCo documentation states that for collision purposes, meshes
+        // are always replaced with their convex hulls. Therefore, we set the
+        // approximation attribute to convexHull explicitly.
+        pxr::SdfPath approximation_attr = CreateAttributeSpec(
+            data_, geom_path, pxr::UsdPhysicsTokens->physicsApproximation,
+            pxr::SdfValueTypeNames->Token, pxr::SdfVariabilityUniform);
+        SetAttributeDefault(data_, approximation_attr,
+                            pxr::UsdPhysicsTokens->convexHull);
+      }
    }

    mjsDefault *spec_default = mjs_getDefault(geom->element);