Don't do GUI rendering when rendering to texture.

PiperOrigin-RevId: 842089364
Change-Id: Iaecebdc677e946c7fc618395205097462a56f2d1

src/experimental/filament/filament/filament_context.cc

@@ -145,7 +145,7 @@ void FilamentContext::Render(const mjrRect& viewport, const mjvScene* scene,
 
   // Draw the GUI. We do this after processing the scene in case there are any
   // label elements in the scene.
-  if (gui_view_) {
+  if (gui_view_ && !render_to_texture_) {
     DrawGui(scene_view_.get());
 
     // Prepare the filament Renderable that contains the GUI draw commands. We