Add write_physics_ as a state variable on ModelWriter.

This way we don't have to worry about passing the write_physics param everywhere.

PiperOrigin-RevId: 764394280
Change-Id: I2c879ae57bdc30f50189960864097c932f967330

src/experimental/usd/plugins/mjcf/mujoco_to_usd.cc

@@ -166,6 +166,9 @@ class ModelWriter {
     // Create the world body.
     body_paths_[kWorldIndex] = WriteWorldBody(kWorldIndex);
 
+    // Set working parameters.
+    write_physics_ = write_physics;
+
     SetLayerMetadata(data_, pxr::SdfFieldKeys->Documentation,
                      "Generated by mujoco model writer.");
     // Mujoco is Z up by default.
@@ -181,9 +184,9 @@ class ModelWriter {
     WritePhysicsScene();
 
     // Author mesh scope + mesh prims to be referenced.
-    WriteMeshes(write_physics);
+    WriteMeshes();
     WriteMaterials();
-    WriteBodies(write_physics);
+    WriteBodies();
   }
 
  private:
@@ -199,6 +202,8 @@ class ModelWriter {
   std::vector<pxr::SdfPath> body_paths_;
   // Mapping from mesh names to Mesh prim path.
   std::unordered_map<std::string, pxr::SdfPath> mesh_paths_;
+  // Whether to write physics data.
+  bool write_physics_ = false;
 
   // Given a name index and a parent prim path this returns a
   // token such that appending it to the parent prim path does not
@@ -299,8 +304,7 @@ class ModelWriter {
     SetAttributeDefault(data_, xform_op_order_path, new_order);
   }
 
-  void WriteMesh(const mjsMesh *mesh, const pxr::SdfPath &parent_path,
-                 bool write_physics) {
+  void WriteMesh(const mjsMesh *mesh, const pxr::SdfPath &parent_path) {
     auto name = GetAvailablePrimName(*mesh->name, pxr::UsdGeomTokens->Mesh,
                                      parent_path);
     pxr::SdfPath subcomponent_path =
@@ -310,7 +314,7 @@ class ModelWriter {
                        pxr::UsdGeomTokens->Mesh);
     mesh_paths_[*mesh->name] = subcomponent_path;
 
-    if (write_physics) {
+    if (write_physics_) {
       ApplyApiSchema(data_, mesh_path, MjcPhysicsTokens->MeshCollisionAPI);
 
       pxr::TfToken inertia = MjcPhysicsTokens->legacy;
@@ -602,7 +606,7 @@ class ModelWriter {
     }
   }
 
-  void WriteMeshes(bool write_physics) {
+  void WriteMeshes() {
     // Create a scope for the meshes to keep things organized
     pxr::SdfPath scope_path =
         CreatePrimSpec(data_, body_paths_[kWorldIndex], kTokens->meshScope,
@@ -614,7 +618,7 @@ class ModelWriter {
 
     mjsMesh *mesh = mjs_asMesh(mjs_firstElement(spec_, mjOBJ_MESH));
     while (mesh) {
-      WriteMesh(mesh, scope_path, write_physics);
+      WriteMesh(mesh, scope_path);
       mesh = mjs_asMesh(mjs_nextElement(spec_, mesh->element));
     }
   }
@@ -1016,7 +1020,7 @@ class ModelWriter {
         site_path, pxr::VtArray<pxr::TfToken>{kTokens->xformOpTransform});
   }
 
-  void WriteGeom(mjsGeom *geom, const mjsBody *body, bool write_physics) {
+  void WriteGeom(mjsGeom *geom, const mjsBody *body) {
     const int body_id = mjs_getId(body->element);
     const auto &body_path = body_paths_[body_id];
 
@@ -1052,8 +1056,8 @@ class ModelWriter {
 
     // Apply the physics schemas if we are writing physics and the
     // geom participates in collisions.
-    if (write_physics && (model_->geom_contype[geom_id] != 0 ||
-                          model_->geom_conaffinity[geom_id] != 0)) {
+    if (write_physics_ && (model_->geom_contype[geom_id] != 0 ||
+                           model_->geom_conaffinity[geom_id] != 0)) {
       ApplyApiSchema(data_, geom_path,
                      pxr::UsdPhysicsTokens->PhysicsCollisionAPI);
       ApplyApiSchema(data_, geom_path, MjcPhysicsTokens->CollisionAPI);
@@ -1178,10 +1182,10 @@ class ModelWriter {
     }
   }
 
-  void WriteGeoms(mjsBody *body, bool write_physics) {
+  void WriteGeoms(mjsBody *body) {
     mjsGeom *geom = mjs_asGeom(mjs_firstChild(body, mjOBJ_GEOM, false));
     while (geom) {
-      WriteGeom(geom, body, write_physics);
+      WriteGeom(geom, body);
       geom = mjs_asGeom(mjs_nextChild(body, geom->element, false));
     }
   }
@@ -1268,7 +1272,7 @@ class ModelWriter {
     }
   }
 
-  void WriteBody(mjsBody *body, bool write_physics) {
+  void WriteBody(mjsBody *body) {
     int body_id = mjs_getId(body->element);
     // This should be safe as we process parent bodies before children.
     mjsBody *parent = mjs_getParent(body->element);
@@ -1286,7 +1290,7 @@ class ModelWriter {
     SetPrimKind(data_, body_path, kind);
 
     // Apply the PhysicsRigidBodyAPI schema if we are writing physics.
-    if (write_physics) {
+    if (write_physics_) {
       // If the body had a mass specified then it must have either inertia or
       // fullinertia specified per inertia element XML documentation.
       // Therefore it is sufficient to check if the mass is non-zero to see if
@@ -1373,17 +1377,17 @@ class ModelWriter {
     body_paths_[body_id] = body_path;
   }
 
-  void WriteBodies(bool write_physics) {
+  void WriteBodies() {
     mjsBody *body = mjs_asBody(mjs_firstElement(spec_, mjOBJ_BODY));
     while (body) {
       // Only write a rigidbody if we are not the world body.
       // We fall through since the world body might have static
       // geom children.
       if (mjs_getId(body->element) != kWorldIndex) {
-        WriteBody(body, write_physics);
+        WriteBody(body);
       }
       WriteSites(body);
-      WriteGeoms(body, write_physics);
+      WriteGeoms(body);
       WriteCameras(body);
       WriteLights(body);
       body = mjs_asBody(mjs_nextElement(spec_, body->element));