Refactor FilamentContext to prepare for upcoming changes.

Separate out the parts of the FilamentContext initialization that
depends on the mjModel into a separate Init function.

PiperOrigin-RevId: 890373341
Change-Id: I06b524668cd60dad804d437958f4f6606c46200b

src/experimental/filament/filament/filament_context.cc

@@ -49,9 +49,8 @@
 
 namespace mujoco {
 
-FilamentContext::FilamentContext(const mjrFilamentConfig* config,
-                                 const mjModel* model)
-    : config_(*config), model_(model) {
+FilamentContext::FilamentContext(const mjrFilamentConfig* config)
+    : config_(*config) {
   FilamentPlatformSetup setup = CreateFilamentPlatform(config_);
   platform_ = std::move(setup.platform);
 
@@ -63,32 +62,16 @@ FilamentContext::FilamentContext(const mjrFilamentConfig* config,
   engine_ = engine_builder.build();
 
   renderer_ = engine_->createRenderer();
-
-  const int width = model_->vis.global.offwidth;
-  const int height = model_->vis.global.offheight;
   #ifdef __EMSCRIPTEN__
     window_swap_chain_ = engine_->createSwapChain(nullptr);
   #else
   if (config_.native_window) {
     window_swap_chain_ = engine_->createSwapChain(config_.native_window);
   } else {
-    window_swap_chain_ = engine_->createSwapChain(width, height);
+    window_swap_chain_ = engine_->createSwapChain(config_.width, config_.height);
   }
   #endif
-
-  offscreen_swap_chain_ = engine_->createSwapChain(width, height);
-  object_manager_ = std::make_unique<ObjectManager>(model, engine_);
-
-  // Set clear options.
-  filament::Renderer::ClearOptions opts;
-  opts.clear = true;
-  opts.discard = true;
-  opts.clearColor = ReadElement(model_, "filament.clearColor",
-                                filament::math::float4(0, 0, 0, 1));
-  renderer_->setClearOptions(opts);
-
-  scene_view_ = std::make_unique<SceneView>(engine_, object_manager_.get());
-  gui_view_ = std::make_unique<GuiView>(engine_, object_manager_.get());
+  offscreen_swap_chain_ = engine_->createSwapChain(config_.width, config_.height);
 }
 
 FilamentContext::~FilamentContext() {
@@ -102,6 +85,20 @@ FilamentContext::~FilamentContext() {
   filament::Engine::destroy(engine_);
 }
 
+void FilamentContext::Init(const mjModel* model) {
+  object_manager_ = std::make_unique<ObjectManager>(model, engine_);
+  scene_view_ = std::make_unique<SceneView>(engine_, object_manager_.get());
+  gui_view_ = std::make_unique<GuiView>(engine_, object_manager_.get());
+
+  // Set clear options.
+  filament::Renderer::ClearOptions opts;
+  opts.clear = true;
+  opts.discard = true;
+  opts.clearColor = ReadElement(model, "filament.clearColor",
+                                filament::math::float4(0, 0, 0, 1));
+  renderer_->setClearOptions(opts);
+}
+
 void FilamentContext::Render(const mjrRect& viewport, const mjvScene* scene) {
   // If we're rendering to the window, and the window size has changed, we need
   // to reacquire the swap chain.

src/experimental/filament/filament/filament_context.h

@@ -35,9 +35,11 @@ namespace mujoco {
 // Manages the filament renderer that is exposed via the mjr functions.
 class FilamentContext {
  public:
-  FilamentContext(const mjrFilamentConfig* config, const mjModel* model);
+  explicit FilamentContext(const mjrFilamentConfig* config);
   ~FilamentContext();
 
+  void Init(const mjModel* model);
+
   void Render(const mjrRect& viewport, const mjvScene* scene);
 
   void SetFrameBuffer(int framebuffer);
@@ -70,7 +72,6 @@ class FilamentContext {
   void DestroyRenderTargets();
 
   mjrFilamentConfig config_;
-  const mjModel* model_ = nullptr;
 
   filament::Engine* engine_ = nullptr;
   filament::Renderer* renderer_ = nullptr;

src/experimental/filament/render_context_filament.cc

@@ -49,7 +49,8 @@ void mjrf_makeFilamentContext(const mjModel* m, mjrContext* con,
   if (g_filament_context != nullptr) {
     mju_error("Context already exists!");
   }
-  g_filament_context = new mujoco::FilamentContext(config, m);
+  g_filament_context = new mujoco::FilamentContext(config);
+  g_filament_context->Init(m);
 }
 
 void mjrf_defaultContext(mjrContext* con) {
@@ -60,6 +61,8 @@ void mjrf_makeContext(const mjModel* m, mjrContext* con, int fontscale) {
   mjr_freeContext(con);
   mjrFilamentConfig cfg;
   mjrf_defaultFilamentConfig(&cfg);
+  cfg.width = m->vis.global.offwidth;
+  cfg.height = m->vis.global.offheight;
   mjrf_makeFilamentContext(m, con, &cfg);
 }
 

src/experimental/filament/render_context_filament.h

@@ -39,6 +39,10 @@ struct mjrFilamentConfig {
   // The native window handle into which we can render directly.
   void* native_window;
 
+  // The initial width and height of the offscreen framebuffer.
+  int width;
+  int height;
+
   // The backend graphics API to use.
   int graphics_api;
 

src/experimental/platform/renderer.cc

@@ -88,6 +88,8 @@ void Renderer::Init(const mjModel* model) {
       mjrFilamentConfig render_config;
       mjrf_defaultFilamentConfig(&render_config);
       render_config.native_window = native_window_;
+      render_config.width = model->vis.global.offwidth;
+      render_config.height = model->vis.global.offheight;
       render_config.force_software_rendering = IsSoftware(gfx_);
       render_config.graphics_api =
           IsOpenGl(gfx_) || IsWebGl(gfx_) ? mjGFX_OPENGL : mjGFX_VULKAN;