Handle null camera and vis_option.

PiperOrigin-RevId: 865088406
Change-Id: I4a3bf7f6cb696de1461bc53fd5d77b941ea0c0c5

src/experimental/platform/renderer.cc

@@ -91,6 +91,17 @@ void Renderer::Render(const mjModel* model, mjData* data,
     return;
   }
 
+  mjvCamera default_cam;
+  if (camera == nullptr) {
+    mjv_defaultCamera(&default_cam);
+    camera = &default_cam;
+  }
+  mjvOption default_opt;
+  if (vis_option == nullptr) {
+    mjv_defaultOption(&default_opt);
+    vis_option = &default_opt;
+  }
+
   mjv_updateScene(model, data, vis_option, perturb, camera, mjCAT_ALL,
                   &scene_);
 

src/experimental/platform/renderer.h

@@ -57,7 +57,7 @@ class Renderer {
   using Seconds = std::chrono::duration<double>;
   using Milliseconds = std::chrono::duration<double, std::milli>;
 
-  explicit Renderer(void* native_window);
+  explicit Renderer(void* native_window = nullptr);
   ~Renderer();
 
   Renderer(const Renderer&) = delete;