Move Render logic into the Scene/Gui View classes.

This is in preparation for an upcoming change.

PiperOrigin-RevId: 886203890
Change-Id: I91eba35b394898d942f66f75e947c450b924a973

src/experimental/filament/filament/filament_context.cc

@@ -180,14 +180,10 @@ void FilamentContext::Render(const mjrRect& viewport, const mjvScene* scene,
     }
 
     if (renderer_->beginFrame(window_swap_chain_)) {
-      filament::View* fview = scene_view_->PrepareRenderView(last_render_mode_);
-      renderer_->render(fview);
+      scene_view_->Render(renderer_, last_render_mode_);
 
-      if (gui_swap_chain_target_ == kWindowSwapChain) {
-        fview = gui_view_ ? gui_view_->PrepareRenderView() : nullptr;
-        if (fview) {
-          renderer_->render(fview);
-        }
+      if (gui_view_ && gui_swap_chain_target_ == kWindowSwapChain) {
+        gui_view_->Render(renderer_);
       }
 
       renderer_->endFrame();
@@ -299,27 +295,11 @@ void FilamentContext::ReadPixels(mjrRect viewport, unsigned char* rgb,
 
   if (rgb) {
     if (renderer_->beginFrame(offscreen_swap_chain_)) {
-      filament::View* fview =
-          scene_view_->PrepareRenderView(last_render_mode_);
-
-      // We need to disable msaa in order to render to texture.
-      auto options = fview->getMultiSampleAntiAliasingOptions();
-      fview->setMultiSampleAntiAliasingOptions({
-          .enabled = false,
-      });
-      fview->setRenderTarget(color_target_);
-      renderer_->render(fview);
-      fview->setRenderTarget(nullptr);
-      fview->setMultiSampleAntiAliasingOptions(options);
+      scene_view_->Render(renderer_, last_render_mode_, color_target_);
 
       // Render the GUI to the texture as well if requested.
-      if (gui_swap_chain_target_ == kOffscreenSwapChain) {
-        fview = gui_view_ ? gui_view_->PrepareRenderView() : nullptr;
-        if (fview) {
-          fview->setRenderTarget(color_target_);
-          renderer_->render(fview);
-          fview->setRenderTarget(nullptr);
-        }
+      if (gui_view_ && gui_swap_chain_target_ == kOffscreenSwapChain) {
+        gui_view_->Render(renderer_, color_target_);
       }
 
       const size_t num_bytes = viewport.width * viewport.height * 3;
@@ -331,11 +311,8 @@ void FilamentContext::ReadPixels(mjrRect viewport, unsigned char* rgb,
 
   if (depth) {
     if (renderer_->beginFrame(offscreen_swap_chain_)) {
-      filament::View* fview =
-          scene_view_->PrepareRenderView(SceneView::DrawMode::kDepth);
-      fview->setRenderTarget(depth_target_);
-      renderer_->render(fview);
-      fview->setRenderTarget(nullptr);
+      scene_view_->Render(renderer_, SceneView::DrawMode::kDepth,
+                          depth_target_);
 
       const size_t num_bytes = viewport.width * viewport.height * sizeof(float);
       ReadDepthPixels(renderer_, depth_target_, viewport, depth, num_bytes);

src/experimental/filament/filament/gui_view.cc

@@ -23,6 +23,7 @@
 #include <imgui.h>
 #include <filament/Engine.h>
 #include <filament/RenderableManager.h>
+#include <filament/Renderer.h>
 #include <filament/TextureSampler.h>
 #include <filament/Viewport.h>
 #include <math/vec4.h>
@@ -371,8 +372,15 @@ filament::MaterialInstance* GuiView::GetMaterialInstance(int index,
   return instance;
 }
 
-filament::View* GuiView::PrepareRenderView() {
-  return num_elements_ > 0 ? view_ : nullptr;
+void GuiView::Render(filament::Renderer* renderer,
+                     filament::RenderTarget* target) {
+  if (num_elements_ == 0) {
+    return;
+  }
+
+  view_->setRenderTarget(target);
+  renderer->render(view_);
+  view_->setRenderTarget(nullptr);
 }
 
 static ImVec2 ClipSpaceToWindowCoordinates(float x, float y) {

src/experimental/filament/filament/gui_view.h

@@ -44,8 +44,8 @@ class GuiView {
   // correctly synced.
   void UpdateRenderable();
 
-  // Returns the filament::View used to render the UX scene.
-  filament::View* PrepareRenderView();
+  void Render(filament::Renderer* renderer,
+              filament::RenderTarget* target = nullptr);
 
   // Uploads texture to be used with ImGui's Image and ImageButton functions.
   uintptr_t UploadImage(uintptr_t tex_id, const uint8_t* pixels, int width,

src/experimental/filament/filament/scene_view.cc

@@ -26,6 +26,7 @@
 #include <filament/Material.h>
 #include <filament/Options.h>
 #include <filament/RenderableManager.h>
+#include <filament/Renderer.h>
 #include <filament/Skybox.h>
 #include <filament/TransformManager.h>
 #include <filament/View.h>
@@ -204,6 +205,26 @@ SceneView::~SceneView() {
   engine_->destroy(scene_);
 }
 
+void SceneView::Render(filament::Renderer* renderer, DrawMode draw_mode,
+                       filament::RenderTarget* target) {
+  filament::View* view = PrepareRenderView(draw_mode);
+  filament::MultiSampleAntiAliasingOptions options =
+      view->getMultiSampleAntiAliasingOptions();
+
+  if (target) {
+    // We need to disable msaa in order to render to texture.
+    view->setMultiSampleAntiAliasingOptions({.enabled = false});
+  }
+
+  view->setRenderTarget(target);
+  renderer->render(view);
+  view->setRenderTarget(nullptr);
+
+  if (target) {
+    view->setMultiSampleAntiAliasingOptions(options);
+  }
+}
+
 filament::View* SceneView::PrepareRenderView(DrawMode mode) {
   for (auto& iter : drawables_) {
     iter->SetDrawMode(mode);

src/experimental/filament/filament/scene_view.h

@@ -67,8 +67,8 @@ class SceneView {
 
   using DrawMode = Material::DrawMode;
 
-  // Prepares and returns the filament View for the given draw mode.
-  filament::View* PrepareRenderView(DrawMode mode);
+  void Render(filament::Renderer* renderer, DrawMode draw_mode,
+              filament::RenderTarget* target = nullptr);
 
   // Accessors.
   filament::Engine* GetEngine() const;
@@ -79,6 +79,9 @@ class SceneView {
   SceneView& operator=(const SceneView&) = delete;
 
  private:
+  // Prepares and returns the filament View for the given draw mode.
+  filament::View* PrepareRenderView(DrawMode mode);
+
   void UpdateCamera(const mjvGLCamera* cameras);
 
   void PrepareLights();