Split Renderer class into explicit "classic" and "filament" classes.

PiperOrigin-RevId: 960272089
Change-Id: I9494472b7b8e838a75beaf0cd68e5ce4b42a80a4

python/mujoco/experimental/studio/native_viewer.cc

@@ -26,8 +26,8 @@
 #include <imgui.h>
 #include <implot.h>
 #include <mujoco/mujoco.h>
+#include <mujoco/experimental/platform/hal/filament_renderer.h>
 #include <mujoco/experimental/platform/hal/graphics_mode.h>
-#include <mujoco/experimental/platform/hal/renderer.h>
 #include <mujoco/experimental/platform/hal/window.h>
 #include <mujoco/experimental/platform/sys_utils.h>
 #include "structs.h"
@@ -119,7 +119,7 @@ class Viewer {
                                                          width, height, config);
     ImPlot::CreateContext();
 
-    renderer_ = std::make_unique<mujoco::platform::Renderer>(
+    renderer_ = std::make_unique<mujoco::platform::FilamentRenderer>(
         window_->GetNativeWindowHandle(), config.gfx_mode);
   }
 

python/mujoco/experimental/studio/renderer.cc

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include <mujoco/experimental/platform/hal/renderer.h>
+#include <mujoco/experimental/platform/hal/filament_renderer.h>
 
 #include <cstddef>
 #include <memory>
@@ -32,7 +32,7 @@ namespace mujoco::python {
 
 class Renderer {
  public:
-  using RendererImpl = mujoco::platform::Renderer;
+  using RendererImpl = mujoco::platform::FilamentRenderer;
   using GraphicsMode = mujoco::platform::GraphicsMode;
 
   Renderer(const std::string& graphics_mode_str) {

python/mujoco/experimental/studio/web/web_client.cc

@@ -43,7 +43,7 @@
 #include <imgui.h>
 #include <implot.h>
 #include <mujoco/mujoco.h>
-#include "experimental/platform/hal/renderer.h"
+#include "experimental/platform/hal/filament_renderer.h"
 #include "experimental/platform/hal/window.h"
 #include "experimental/platform/sim/model_holder.h"
 #include "experimental/platform/ux/interaction.h"
@@ -757,7 +757,7 @@ void StartApp() {
                                                             1400, 720, config);
   ImPlot::CreateContext();  // Needed if the server app uses ImPlot.
 
-  g_app.renderer = new mujoco::platform::Renderer(
+  g_app.renderer = new mujoco::platform::FilamentRenderer(
       g_app.window->GetNativeWindowHandle(), config.gfx_mode);
 
   // Initialize an empty dummy scene so Filament and ImGui are ready to render

src/experimental/platform/CMakeLists.txt

@@ -26,11 +26,14 @@ target_sources(${MUJOCO_PLATFORM_TARGET_NAME}
         resources.h
         sys_utils.cc
         sys_utils.h
+        hal/classic_renderer.cc
+        hal/classic_renderer.h
         hal/egl_utils.cc
         hal/egl_utils.h
+        hal/filament_renderer.cc
+        hal/filament_renderer.h
         hal/graphics_mode.cc
         hal/graphics_mode.h
-        hal/renderer.cc
         hal/renderer.h
         hal/window.cc
         hal/window.h

src/experimental/platform/hal/classic_renderer.cc

@@ -0,0 +1,202 @@
+// Copyright 2025 DeepMind Technologies Limited
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "experimental/platform/hal/classic_renderer.h"
+
+#include <algorithm>
+#include <chrono>
+#include <cstddef>
+#include <memory>
+#include <span>
+#include <utility>
+
+#include <backends/imgui_impl_opengl3.h>
+#include <imgui.h>
+#include <mujoco/mujoco.h>
+#if !defined(__EMSCRIPTEN__) && !defined(__APPLE__)
+#include "experimental/platform/hal/egl_utils.h"
+#endif
+#include "experimental/platform/hal/graphics_mode.h"
+
+namespace mujoco::platform {
+
+static void FlipImage(unsigned char* pixels, int width, int height, int bpp) {
+  const int row_size = width * bpp;
+  for (int i = 0; i < height / 2; ++i) {
+    unsigned char* top_row = pixels + i * row_size;
+    unsigned char* bottom_row = pixels + (height - 1 - i) * row_size;
+    for (int j = 0; j < row_size; ++j) {
+      std::swap(top_row[j], bottom_row[j]);
+    }
+  }
+}
+
+ClassicRenderer::ClassicRenderer(void* native_window, GraphicsMode gfx)
+    : gfx_(gfx) {
+  if (native_window == nullptr) {
+#if !defined(__EMSCRIPTEN__) && !defined(__APPLE__)
+    graphics_api_context_ = CreateEglContext();
+#endif
+  }
+  if (ImGui::GetCurrentContext()) {
+    ImGui_ImplOpenGL3_Init();
+  }
+}
+
+ClassicRenderer::~ClassicRenderer() {
+  if (ImGui::GetCurrentContext()) {
+    ImGui_ImplOpenGL3_Shutdown();
+  }
+
+  Deinit();
+  graphics_api_context_.reset();
+}
+
+void ClassicRenderer::Init(const mjModel* model) {
+  Deinit();
+  if (model) {
+    mjr_defaultContext(&render_context_);
+    mjr_makeContext(model, &render_context_, mjFONTSCALE_150);
+    mjv_defaultScene(&scene_);
+    mjv_makeScene(model, &scene_, 2000);
+    initialized_ = true;
+  }
+}
+
+void ClassicRenderer::Deinit() {
+  if (initialized_) {
+    mjv_freeScene(&scene_);
+    mjr_freeContext(&render_context_);
+    initialized_ = false;
+  }
+}
+
+void ClassicRenderer::Render(const mjModel* model, mjData* data,
+                             const mjvPerturb* perturb, mjvCamera* camera,
+                             const mjvOption* vis_option, int width, int height,
+                             std::span<std::byte> pixels,
+                             std::span<mjvGeom> extra_geoms) {
+  if (!initialized_) {
+    return;
+  }
+
+  mjvCamera default_cam;
+  if (camera == nullptr) {
+    if (model) {
+      mjv_defaultFreeCamera(model, &default_cam);
+    } else {
+      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_);
+  const int nextra_geoms =
+      std::min<int>(extra_geoms.size(), scene_.maxgeom - scene_.ngeom);
+  for (int i = 0; i < nextra_geoms; ++i) {
+    scene_.geoms[scene_.ngeom++] = extra_geoms[i];
+  }
+
+  const bool render_to_texture = !pixels.empty();
+  if (render_to_texture) {
+    // mjr_readPixels reads to a RGB buffer (i.e. 3 bytes per pixel).
+    if (pixels.size() != width * height * 3) {
+      mju_error("Offscreen mode requires a pixel buffer of size %d.",
+                width * height * 3);
+    }
+    mjr_resizeOffscreen(width, height, &render_context_);
+
+    framebuffer_mode_ = mjFB_OFFSCREEN;
+    mjr_setBuffer(mjFB_OFFSCREEN, &render_context_);
+  }
+
+  const mjrRect viewport = {0, 0, width, height};
+  mjr_render(viewport, &scene_, &render_context_);
+
+  // The filament backend knows how to renders the ImGui draw data. For the
+  // classic backend, we need to render the ImGui draw data ourselves.
+  if (ImGui::GetCurrentContext()) {
+    ImGui_ImplOpenGL3_NewFrame();
+    ImGui::Render();
+    ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
+  }
+
+  if (render_to_texture) {
+    unsigned char* ptr = reinterpret_cast<unsigned char*>(pixels.data());
+    DoReadPixels(width, height, ptr);
+  }
+
+  UpdateFps();
+}
+
+void ClassicRenderer::RenderToTexture(const mjModel* model, mjData* data,
+                                      mjvCamera* camera, int width, int height,
+                                      std::byte* output) {
+  if (!initialized_) {
+    return;
+  }
+
+  mjv_updateCamera(model, data, camera, &scene_);
+  unsigned char* ptr = reinterpret_cast<unsigned char*>(output);
+
+  framebuffer_mode_ = mjFB_OFFSCREEN;
+  mjr_setBuffer(mjFB_OFFSCREEN, &render_context_);
+  const mjrRect viewport = {0, 0, width, height};
+  mjr_render(viewport, &scene_, &render_context_);
+  DoReadPixels(width, height, ptr);
+}
+
+int ClassicRenderer::UploadImage(int texture_id, const std::byte* pixels,
+                                 int width, int height, int bpp) {
+  // unsupported
+  return 0;
+}
+
+void ClassicRenderer::DoReadPixels(int width, int height, unsigned char* rgb) {
+  if (!rgb) {
+    return;
+  }
+  if (framebuffer_mode_ == mjFB_WINDOW) {
+    mju_warning("ReadPixels is only supported for offscreen rendering.");
+    return;
+  }
+
+  const mjrRect viewport = {0, 0, width, height};
+  mjr_readPixels(rgb, nullptr, viewport, &render_context_);
+  mjr_setBuffer(mjFB_WINDOW, &render_context_);
+  FlipImage(rgb, viewport.width, viewport.height, 3);
+  framebuffer_mode_ = mjFB_WINDOW;
+  mjr_setBuffer(mjFB_WINDOW, &render_context_);
+}
+
+double ClassicRenderer::GetFps() { return fps_; }
+
+void ClassicRenderer::UpdateFps() {
+  TimePoint now = std::chrono::steady_clock::now();
+  TimePoint::duration delta_time = now - last_fps_update_;
+  const double interval = std::chrono::duration<double>(delta_time).count();
+  ++frames_;
+  if (interval > 0.2) {  // only update FPS stat at most 5 times per second
+    last_fps_update_ = now;
+    fps_ = frames_ / interval;
+    frames_ = 0;
+  }
+}
+}  // namespace mujoco::platform

src/experimental/platform/hal/classic_renderer.h

@@ -0,0 +1,91 @@
+// Copyright 2025 DeepMind Technologies Limited
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef MUJOCO_SRC_EXPERIMENTAL_PLATFORM_HAL_CLASSIC_RENDERER_H_
+#define MUJOCO_SRC_EXPERIMENTAL_PLATFORM_HAL_CLASSIC_RENDERER_H_
+
+#include <chrono>
+#include <cstddef>
+#include <memory>
+#include <span>
+
+#include <mujoco/mujoco.h>
+#include "experimental/platform/hal/graphics_mode.h"
+#include "experimental/platform/hal/renderer.h"
+
+namespace mujoco::platform {
+
+// Renders the mujoco simulation and the imgui state using the Classic MuJoCo
+// OpenGL renderer.
+class ClassicRenderer : public Renderer {
+ public:
+  ClassicRenderer(void* native_window, GraphicsMode gfx_mode);
+  ~ClassicRenderer();
+
+  ClassicRenderer(const ClassicRenderer&) = delete;
+  ClassicRenderer& operator=(const ClassicRenderer&) = delete;
+
+  // Initializes the renderer with the given mjModel.
+  void Init(const mjModel* model) override;
+
+  // Renders the simulation and ux state. Renders into `pixels` if provided,
+  // otherwise renders to the `native_window` provided at construction.
+  void Render(const mjModel* model, mjData* data, const mjvPerturb* perturb,
+              mjvCamera* camera, const mjvOption* vis_option, int width,
+              int height, std::span<std::byte> pixels = {},
+              std::span<mjvGeom> extra_geoms = {}) override;
+
+  // Populates the given output buffer with RGB888 pixel data. The size of the
+  // output buffer must be at least width * height * 3.
+  void RenderToTexture(const mjModel* model, mjData* data, mjvCamera* camera,
+                       int width, int height, std::byte* output) override;
+
+  // Uploads an image to the backend for GUI rendering, returning the texture
+  // ID for the texture. The ID can be used in subsequent calls to update the
+  // texture data. A nullptr pixels argument will free the texture if it exists.
+  // A texture ID of 0 will create a new texture.
+  int UploadImage(int texture_id, const std::byte* pixels, int width,
+                  int height, int bpp) override;
+
+  // Rendering flags.
+  mjtByte* GetRenderFlags() override { return scene_.flags; }
+
+  // Returns the current frame rate.
+  double GetFps() override;
+
+ private:
+  using Clock = std::chrono::steady_clock;
+  using TimePoint = std::chrono::time_point<Clock>;
+
+  // Resets the renderer; no rendering will occur until Init() is called again.
+  void Deinit();
+
+  void UpdateFps();
+
+  void DoReadPixels(int width, int height, unsigned char* rgb);
+
+  GraphicsMode gfx_ = GraphicsMode::ClassicOpenGl;
+  std::shared_ptr<void> graphics_api_context_ = nullptr;
+  mjrContext render_context_;
+  mjvScene scene_;
+  TimePoint last_fps_update_;
+  int framebuffer_mode_ = 0;
+  int frames_ = 0;
+  double fps_ = 0;
+  bool initialized_ = false;
+};
+
+}  // namespace mujoco::platform
+
+#endif  // MUJOCO_SRC_EXPERIMENTAL_PLATFORM_HAL_CLASSIC_RENDERER_H_

src/experimental/platform/hal/filament_renderer.cc

@@ -0,0 +1,289 @@
+// Copyright 2025 DeepMind Technologies Limited
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "experimental/platform/hal/filament_renderer.h"
+
+#include <algorithm>
+#include <cstddef>
+#include <functional>
+#include <memory>
+#include <span>
+
+#include <mujoco/mjrfilament.h>
+#include <mujoco/mujoco.h>
+#include "experimental/filament/compat/scene_bridge.h"
+#include "experimental/platform/hal/graphics_mode.h"
+#include "experimental/platform/ux/imgui_bridge.h"
+#include "experimental/platform/ux/imgui_widgets.h"
+#include "experimental/platform/ux/plugin.h"
+#include "render/filament/mjrfilament_cpp.h"
+
+namespace mujoco::platform {
+
+static std::function<void()> g_update_gui_callback = nullptr;
+static void PluginUpdate(GuiPlugin* plugin) {
+  if (g_update_gui_callback) {
+    g_update_gui_callback();
+  }
+}
+
+FilamentRenderer::FilamentRenderer(void* native_window, GraphicsMode gfx)
+    : native_window_(native_window), gfx_(gfx) {
+  g_update_gui_callback = [this]() {
+    if (main_scene_) {
+      mjrf_DEBUG_drawImguiEditor(main_scene_.get());
+    }
+  };
+}
+
+FilamentRenderer::~FilamentRenderer() {
+  g_update_gui_callback = nullptr;
+  Deinit();
+}
+
+void FilamentRenderer::Init(const mjModel* model) {
+  Deinit();
+  if (model) {
+    mjrfContextConfig cfg;
+    mjrf_defaultContextConfig(&cfg);
+    cfg.native_window = native_window_;
+    cfg.force_software_rendering = IsSoftware(gfx_);
+    cfg.graphics_api = IsOpenGl(gfx_) || IsWebGl(gfx_) ? mjGRAPHICS_API_OPENGL
+                                                       : mjGRAPHICS_API_VULKAN;
+    filament_context_ = CreateContext(cfg);
+
+    main_scene_ = CreateScene(filament_context_.get(), {});
+    ux_scene_ = CreateScene(filament_context_.get(), {});
+    scene_bridge_ = std::make_unique<SceneBridge>(filament_context_.get(),
+                                                  main_scene_.get(), model);
+    imgui_bridge_ =
+        std::make_unique<ImguiBridge>(filament_context_.get(), ux_scene_.get());
+    scene_bridge_->SetDrawTextFunction(DrawTextAt);
+
+    mjv_defaultScene(&scene_);
+    mjv_makeScene(model, &scene_, 2000);
+  }
+}
+
+void FilamentRenderer::Deinit() {
+  if (filament_context_) {
+    mjv_freeScene(&scene_);
+    scene_bridge_.reset();
+    imgui_bridge_.reset();
+    ux_scene_.reset();
+    main_scene_.reset();
+    filament_context_.reset();
+  }
+}
+
+void FilamentRenderer::Render(const mjModel* model, mjData* data,
+                              const mjvPerturb* perturb, mjvCamera* camera,
+                              const mjvOption* vis_option, int width,
+                              int height, std::span<std::byte> pixels,
+                              std::span<mjvGeom> extra_geoms) {
+  if (!filament_context_) {
+    return;
+  }
+
+  mjvCamera default_cam;
+  if (camera == nullptr) {
+    if (model) {
+      mjv_defaultFreeCamera(model, &default_cam);
+    } else {
+      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_);
+  const int nextra_geoms =
+      std::min<int>(extra_geoms.size(), scene_.maxgeom - scene_.ngeom);
+  for (int i = 0; i < nextra_geoms; ++i) {
+    scene_.geoms[scene_.ngeom++] = extra_geoms[i];
+  }
+
+  const bool render_to_texture = !pixels.empty();
+  if (render_to_texture) {
+    if (pixels.size() != width * height * 3) {
+      mju_error("Offscreen mode requires a pixel buffer of size %d.",
+                width * height * 3);
+    }
+    framebuffer_mode_ = mjFB_OFFSCREEN + 1;
+  }
+
+  DoRender(width, height);
+
+  if (render_to_texture) {
+    unsigned char* ptr = reinterpret_cast<unsigned char*>(pixels.data());
+    DoReadPixels(width, height, ptr);
+  }
+
+  UpdateFps();
+}
+
+void FilamentRenderer::RenderToTexture(const mjModel* model, mjData* data,
+                                       mjvCamera* camera, int width, int height,
+                                       std::byte* output) {
+  if (!filament_context_) {
+    return;
+  }
+
+  mjv_updateCamera(model, data, camera, &scene_);
+  unsigned char* ptr = reinterpret_cast<unsigned char*>(output);
+
+  framebuffer_mode_ = mjFB_OFFSCREEN;
+  DoRender(width, height);
+  DoReadPixels(width, height, ptr);
+}
+
+int FilamentRenderer::UploadImage(int texture_id, const std::byte* pixels,
+                                  int width, int height, int bpp) {
+  return imgui_bridge_->UploadImage(
+      texture_id, reinterpret_cast<const unsigned char*>(pixels), width, height,
+      bpp);
+}
+
+void FilamentRenderer::DoRender(int width, int height) {
+  const mjrRect viewport = {0, 0, width, height};
+  scene_bridge_->Update(viewport, &scene_);
+  // Update the UX renderable entity after processing the scene in case there
+  // are any elements in the scene which generate UX draw calls (e.g. labels).
+  if (framebuffer_mode_ != 1) {
+    imgui_bridge_->Update();
+  }
+  if (framebuffer_mode_ == 0) {
+    mjrDrawMode draw_mode = mjDRAW_MODE_DEFAULT;
+    if (scene_.flags[mjRND_SEGMENT]) {
+      if (scene_.flags[mjRND_IDCOLOR]) {
+        draw_mode = mjDRAW_MODE_SEGMENTATION_BY_ID;
+      } else {
+        draw_mode = mjDRAW_MODE_SEGMENTATION_BY_COLOR;
+      }
+    } else if (scene_.flags[mjRND_DEPTH]) {
+      draw_mode = mjDRAW_MODE_DEPTH;
+    } else if (scene_.flags[mjRND_WIREFRAME]) {
+      draw_mode = mjDRAW_MODE_WIREFRAME;
+    }
+
+    mjrfRenderRequest reqs[2];
+
+    mjrf_defaultRenderRequest(&reqs[0]);
+    reqs[0].scene = main_scene_.get();
+    reqs[0].draw_mode = draw_mode;
+    reqs[0].camera = scene_bridge_->GetCamera();
+    reqs[0].viewport = viewport;
+    reqs[0].enable_shadows = scene_.flags[mjRND_SHADOW];
+    reqs[0].enable_reflections = scene_.flags[mjRND_REFLECTION];
+
+    mjrf_defaultRenderRequest(&reqs[1]);
+    reqs[1].scene = ux_scene_.get();
+    reqs[1].draw_mode = mjDRAW_MODE_DEFAULT;
+    reqs[1].camera = imgui_bridge_->GetCamera(viewport.width, viewport.height);
+    reqs[1].viewport = viewport;
+    reqs[1].enable_shadows = false;
+    reqs[1].enable_reflections = false;
+    reqs[1].enable_post_processing = false;
+
+    mjrf_render(filament_context_.get(), &reqs[0], 2, nullptr, 0);
+  }
+}
+
+void FilamentRenderer::DoReadPixels(int width, int height, unsigned char* rgb) {
+  if (!rgb) {
+    return;
+  }
+  if (framebuffer_mode_ == 0) {
+    mju_warning("ReadPixels is only supported for offscreen rendering.");
+    return;
+  }
+
+  const mjrRect viewport = {0, 0, width, height};
+  mjrDrawMode draw_mode = mjDRAW_MODE_DEFAULT;
+  if (scene_.flags[mjRND_SEGMENT]) {
+    if (scene_.flags[mjRND_IDCOLOR]) {
+      draw_mode = mjDRAW_MODE_SEGMENTATION_BY_ID;
+    } else {
+      draw_mode = mjDRAW_MODE_SEGMENTATION_BY_COLOR;
+    }
+  } else if (scene_.flags[mjRND_DEPTH]) {
+    draw_mode = mjDRAW_MODE_DEPTH;
+  } else if (scene_.flags[mjRND_WIREFRAME]) {
+    draw_mode = mjDRAW_MODE_WIREFRAME;
+  }
+
+  mjrfRenderTargetConfig config;
+  mjrf_defaultRenderTargetConfig(&config);
+  config.width = viewport.width;
+  config.height = viewport.height;
+  config.color_format = mjPIXEL_FORMAT_RGB8;
+  config.depth_format = mjPIXEL_FORMAT_DEPTH32F;
+  auto target = CreateRenderTarget(filament_context_.get(), config);
+
+  mjrfRenderRequest reqs[2];
+  mjrf_defaultRenderRequest(&reqs[0]);
+  reqs[0].scene = main_scene_.get();
+  reqs[0].draw_mode = draw_mode;
+  reqs[0].camera = scene_bridge_->GetCamera();
+  reqs[0].target = target.get();
+  reqs[0].viewport = viewport;
+  reqs[0].enable_shadows = scene_.flags[mjRND_SHADOW];
+  reqs[0].enable_reflections = scene_.flags[mjRND_REFLECTION];
+
+  mjrf_defaultRenderRequest(&reqs[1]);
+  reqs[1].scene = ux_scene_.get();
+  reqs[1].draw_mode = mjDRAW_MODE_DEFAULT;
+  reqs[1].camera = imgui_bridge_->GetCamera(viewport.width, viewport.height);
+  reqs[1].target = target.get();
+  reqs[1].viewport = viewport;
+  reqs[1].enable_shadows = false;
+  reqs[1].enable_reflections = false;
+  reqs[1].enable_post_processing = false;
+
+  mjrfReadPixelsRequest read_request;
+  mjrf_defaultReadPixelsRequest(&read_request);
+  read_request.target = target.get();
+  read_request.output = rgb;
+  read_request.num_bytes = viewport.width * viewport.height * 3;
+
+  const int num_requests = (framebuffer_mode_ == 2) ? 2 : 1;
+  const mjrfFrameHandle frame = mjrf_render(filament_context_.get(), &reqs[0],
+                                            num_requests, &read_request, 1);
+  mjrf_waitForFrame(filament_context_.get(), frame);
+  framebuffer_mode_ = mjFB_WINDOW;
+}
+
+double FilamentRenderer::GetFps() { return fps_; }
+
+void FilamentRenderer::UpdateFps() {
+  mjrfFrameStats stats;
+  mjrf_defaultFrameStats(&stats);
+  mjrf_getFrameStats(filament_context_.get(), 0, &stats);
+  fps_ = stats.frame_rate;
+}
+
+}  // namespace mujoco::platform
+
+mjPLUGIN_LIB_INIT(renderer) {
+  mujoco::platform::GuiPlugin plugin;
+  plugin.name = "Filament";
+  plugin.update = [](mujoco::platform::GuiPlugin* self) {
+    mujoco::platform::PluginUpdate(self);
+  };
+  mujoco::platform::RegisterPlugin(plugin);
+}

src/experimental/platform/hal/filament_renderer.h

@@ -0,0 +1,100 @@
+// Copyright 2025 DeepMind Technologies Limited
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef MUJOCO_SRC_EXPERIMENTAL_PLATFORM_HAL_FILAMENT_RENDERER_H_
+#define MUJOCO_SRC_EXPERIMENTAL_PLATFORM_HAL_FILAMENT_RENDERER_H_
+
+#include <cstddef>
+#include <memory>
+#include <span>
+
+#include <mujoco/mjrfilament.h>
+#include <mujoco/mujoco.h>
+#include "experimental/filament/compat/scene_bridge.h"
+#include "experimental/platform/hal/graphics_mode.h"
+#include "experimental/platform/hal/renderer.h"
+#include "experimental/platform/ux/imgui_bridge.h"
+#include "render/filament/mjrfilament_cpp.h"
+
+namespace mujoco::platform {
+
+// Renders the mujoco simulation and the imgui state using the Filament-based
+// MuJoCo renderer.
+//
+// For OpenGL, two different Filament configurations are available: normal and
+// headless. Normal rendering assumes that we will be rendering to an x11
+// window and therefore will use a x11-based context. Headless assumes that we
+// will be rendering to a texture and will use an EGL context. Vulkan and WebGL
+// have no need for such a distinction. If rendering to a window surface (e.g.
+// x11), it requires a pointer to the native window to do so.
+class FilamentRenderer : public Renderer {
+ public:
+  FilamentRenderer(void* native_window, GraphicsMode gfx_mode);
+  ~FilamentRenderer();
+
+  FilamentRenderer(const FilamentRenderer&) = delete;
+  FilamentRenderer& operator=(const FilamentRenderer&) = delete;
+
+  // Initializes the renderer with the given mjModel.
+  void Init(const mjModel* model) override;
+
+  // Renders the simulation and ux state. Renders into `pixels` if provided,
+  // otherwise renders to the `native_window` provided at construction.
+  void Render(const mjModel* model, mjData* data, const mjvPerturb* perturb,
+              mjvCamera* camera, const mjvOption* vis_option, int width,
+              int height, std::span<std::byte> pixels = {},
+              std::span<mjvGeom> extra_geoms = {}) override;
+
+  // Populates the given output buffer with RGB888 pixel data. The size of the
+  // output buffer must be at least width * height * 3.
+  void RenderToTexture(const mjModel* model, mjData* data, mjvCamera* camera,
+                       int width, int height, std::byte* output) override;
+
+  // Uploads an image to the backend for GUI rendering, returning the texture
+  // ID for the texture. The ID can be used in subsequent calls to update the
+  // texture data. A nullptr pixels argument will free the texture if it exists.
+  // A texture ID of 0 will create a new texture.
+  int UploadImage(int texture_id, const std::byte* pixels, int width,
+                  int height, int bpp) override;
+
+  // Rendering flags.
+  mjtByte* GetRenderFlags() override { return scene_.flags; }
+
+  // Returns the current frame rate.
+  double GetFps() override;
+
+ private:
+  // Resets the renderer; no rendering will occur until Init() is called again.
+  void Deinit();
+
+  void UpdateFps();
+
+  void DoRender(int width, int height);
+  void DoReadPixels(int width, int height, unsigned char* rgb);
+
+  void* native_window_ = nullptr;
+  GraphicsMode gfx_ = GraphicsMode::FilamentVulkan;
+  UniquePtr<mjrfContext> filament_context_{nullptr, nullptr};
+  UniquePtr<mjrfScene> main_scene_{nullptr, nullptr};
+  UniquePtr<mjrfScene> ux_scene_{nullptr, nullptr};
+  std::unique_ptr<SceneBridge> scene_bridge_;
+  std::unique_ptr<ImguiBridge> imgui_bridge_;
+  int framebuffer_mode_ = 0;
+  mjvScene scene_;
+  double fps_ = 0;
+};
+
+}  // namespace mujoco::platform
+
+#endif  // MUJOCO_SRC_EXPERIMENTAL_PLATFORM_HAL_FILAMENT_RENDERER_H_

src/experimental/platform/hal/renderer.cc

@@ -1,385 +0,0 @@
-// Copyright 2025 DeepMind Technologies Limited
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-#include "experimental/platform/hal/renderer.h"
-
-#include <algorithm>
-#include <chrono>
-#include <cstddef>
-#include <functional>
-#include <memory>
-#include <span>
-#include <utility>
-
-#include <backends/imgui_impl_opengl3.h>
-#include <imgui.h>
-#include <mujoco/mujoco.h>
-#if !defined(__EMSCRIPTEN__) && !defined(__APPLE__)
-#include "experimental/platform/hal/egl_utils.h"
-#endif
-#include <mujoco/mjrfilament.h>
-#include "experimental/filament/compat/scene_bridge.h"
-#include "experimental/platform/hal/graphics_mode.h"
-#include "experimental/platform/ux/imgui_bridge.h"
-#include "experimental/platform/ux/imgui_widgets.h"
-#include "experimental/platform/ux/plugin.h"
-#include "render/filament/mjrfilament_cpp.h"
-
-namespace mujoco::platform {
-
-static std::function<void()> g_update_gui_callback = nullptr;
-static void PluginUpdate(GuiPlugin* plugin) {
-  if (g_update_gui_callback) {
-    g_update_gui_callback();
-  }
-}
-
-static void FlipImage(unsigned char* pixels, int width, int height, int bpp) {
-  const int row_size = width * bpp;
-  for (int i = 0; i < height / 2; ++i) {
-    unsigned char* top_row = pixels + i * row_size;
-    unsigned char* bottom_row = pixels + (height - 1 - i) * row_size;
-    for (int j = 0; j < row_size; ++j) {
-      std::swap(top_row[j], bottom_row[j]);
-    }
-  }
-}
-
-Renderer::Renderer(void* native_window, GraphicsMode gfx)
-    : native_window_(native_window), gfx_(gfx) {
-  if (IsClassic(gfx_)) {
-    if (native_window == nullptr) {
-#if !defined(__EMSCRIPTEN__) && !defined(__APPLE__)
-      graphics_api_context_ = CreateEglContext();
-#endif
-    }
-    if (ImGui::GetCurrentContext()) {
-      ImGui_ImplOpenGL3_Init();
-    }
-  }
-
-  g_update_gui_callback = [this]() {
-    if (main_scene_) {
-      mjrf_DEBUG_drawImguiEditor(main_scene_.get());
-    }
-  };
-}
-
-Renderer::~Renderer() {
-  g_update_gui_callback = nullptr;
-  if (IsClassic(gfx_)) {
-    if (ImGui::GetCurrentContext()) {
-      ImGui_ImplOpenGL3_Shutdown();
-    }
-  }
-  Deinit();
-  graphics_api_context_.reset();
-}
-
-void Renderer::Init(const mjModel* model) {
-  Deinit();
-  if (model) {
-    if (IsClassic(gfx_)) {
-      mjr_defaultContext(&render_context_);
-      mjr_makeContext(model, &render_context_, mjFONTSCALE_150);
-
-    } else {
-      mjrfContextConfig cfg;
-      mjrf_defaultContextConfig(&cfg);
-      cfg.native_window = native_window_;
-      cfg.force_software_rendering = IsSoftware(gfx_);
-      cfg.graphics_api = IsOpenGl(gfx_) || IsWebGl(gfx_)
-                             ? mjGRAPHICS_API_OPENGL
-                             : mjGRAPHICS_API_VULKAN;
-      filament_context_ = CreateContext(cfg);
-      main_scene_ = CreateScene(filament_context_.get(), {});
-      ux_scene_ = CreateScene(filament_context_.get(), {});
-      scene_bridge_ = std::make_unique<SceneBridge>(filament_context_.get(),
-                                                    main_scene_.get(), model);
-      imgui_bridge_ = std::make_unique<ImguiBridge>(filament_context_.get(),
-                                                    ux_scene_.get());
-      scene_bridge_->SetDrawTextFunction(DrawTextAt);
-    }
-
-    mjv_defaultScene(&scene_);
-    mjv_makeScene(model, &scene_, 2000);
-    initialized_ = true;
-  }
-}
-
-void Renderer::Deinit() {
-  if (initialized_) {
-    mjv_freeScene(&scene_);
-    if (IsClassic(gfx_)) {
-      mjr_freeContext(&render_context_);
-    } else {
-      scene_bridge_.reset();
-      imgui_bridge_.reset();
-      ux_scene_.reset();
-      main_scene_.reset();
-      filament_context_.reset();
-    }
-    initialized_ = false;
-  }
-}
-
-void Renderer::Render(const mjModel* model, mjData* data,
-                      const mjvPerturb* perturb, mjvCamera* camera,
-                      const mjvOption* vis_option, int width, int height,
-                      std::span<std::byte> pixels,
-                      std::span<mjvGeom> extra_geoms) {
-  if (!initialized_) {
-    return;
-  }
-
-  mjvCamera default_cam;
-  if (camera == nullptr) {
-    if (model) {
-      mjv_defaultFreeCamera(model, &default_cam);
-    } else {
-      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_);
-  const int nextra_geoms =
-      std::min<int>(extra_geoms.size(), scene_.maxgeom - scene_.ngeom);
-  for (int i = 0; i < nextra_geoms; ++i) {
-    scene_.geoms[scene_.ngeom++] = extra_geoms[i];
-  }
-
-  const bool render_to_texture = !pixels.empty();
-  if (render_to_texture) {
-    // mjr_readPixels reads to a RGB buffer (i.e. 3 bytes per pixel).
-    if (pixels.size() != width * height * 3) {
-      mju_error("Offscreen mode requires a pixel buffer of size %d.",
-                width * height * 3);
-    }
-    if (IsClassic(gfx_)) {
-      mjr_resizeOffscreen(width, height, &render_context_);
-    }
-
-    // The filament backend supports two offscreen framebuffers.
-    // mjFB_OFFSCREEN renders just the mjvScene data. +1 also includes the
-    // ImGui draw data.
-    DoSetBuffer(IsClassic(gfx_) ? mjFB_OFFSCREEN : mjFB_OFFSCREEN + 1);
-  }
-
-  DoRender(width, height);
-
-  // The filament backend knows how to renders the ImGui draw data. For the
-  // classic backend, we need to render the ImGui draw data ourselves.
-  if (IsClassic(gfx_) && ImGui::GetCurrentContext()) {
-    ImGui_ImplOpenGL3_NewFrame();
-    ImGui::Render();
-    ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
-  }
-
-  if (render_to_texture) {
-    unsigned char* ptr = reinterpret_cast<unsigned char*>(pixels.data());
-    DoReadPixels(width, height, ptr);
-  }
-
-  UpdateFps();
-}
-
-void Renderer::RenderToTexture(const mjModel* model, mjData* data,
-                               mjvCamera* camera, int width, int height,
-                               std::byte* output) {
-  if (!initialized_) {
-    return;
-  }
-
-  mjv_updateCamera(model, data, camera, &scene_);
-  unsigned char* ptr = reinterpret_cast<unsigned char*>(output);
-
-  DoSetBuffer(mjFB_OFFSCREEN);
-  DoRender(width, height);
-  DoReadPixels(width, height, ptr);
-}
-
-int Renderer::UploadImage(int texture_id, const std::byte* pixels, int width,
-                          int height, int bpp) {
-  if (IsClassic(gfx_)) {
-    return 0;
-  } else {
-    return imgui_bridge_->UploadImage(
-        texture_id, reinterpret_cast<const unsigned char*>(pixels), width,
-        height, bpp);
-  }
-}
-
-void Renderer::DoRender(int width, int height) {
-  const mjrRect viewport = {0, 0, width, height};
-  if (IsClassic(gfx_)) {
-    mjr_render(viewport, &scene_, &render_context_);
-  } else {
-    scene_bridge_->Update(viewport, &scene_);
-    // Update the UX renderable entity after processing the scene in case there
-    // are any elements in the scene which generate UX draw calls (e.g. labels).
-    if (framebuffer_mode_ != 1) {
-      imgui_bridge_->Update();
-    }
-    if (framebuffer_mode_ == 0) {
-      mjrDrawMode draw_mode = mjDRAW_MODE_DEFAULT;
-      if (scene_.flags[mjRND_SEGMENT]) {
-        if (scene_.flags[mjRND_IDCOLOR]) {
-          draw_mode = mjDRAW_MODE_SEGMENTATION_BY_ID;
-        } else {
-          draw_mode = mjDRAW_MODE_SEGMENTATION_BY_COLOR;
-        }
-      } else if (scene_.flags[mjRND_DEPTH]) {
-        draw_mode = mjDRAW_MODE_DEPTH;
-      } else if (scene_.flags[mjRND_WIREFRAME]) {
-        draw_mode = mjDRAW_MODE_WIREFRAME;
-      }
-
-      mjrfRenderRequest reqs[2];
-
-      mjrf_defaultRenderRequest(&reqs[0]);
-      reqs[0].scene = main_scene_.get();
-      reqs[0].draw_mode = draw_mode;
-      reqs[0].camera = scene_bridge_->GetCamera();
-      reqs[0].viewport = viewport;
-      reqs[0].enable_shadows = scene_.flags[mjRND_SHADOW];
-      reqs[0].enable_reflections = scene_.flags[mjRND_REFLECTION];
-
-      mjrf_defaultRenderRequest(&reqs[1]);
-      reqs[1].scene = ux_scene_.get();
-      reqs[1].draw_mode = mjDRAW_MODE_DEFAULT;
-      reqs[1].camera = imgui_bridge_->GetCamera(viewport.width, viewport.height);
-      reqs[1].viewport = viewport;
-      reqs[1].enable_shadows = false;
-      reqs[1].enable_reflections = false;
-      reqs[1].enable_post_processing = false;
-
-      mjrf_render(filament_context_.get(), &reqs[0], 2, nullptr, 0);
-    }
-  }
-}
-
-void Renderer::DoSetBuffer(int framebuffer) {
-  framebuffer_mode_ = framebuffer;
-  if (IsClassic(gfx_)) {
-    mjr_setBuffer(framebuffer, &render_context_);
-  }
-}
-
-void Renderer::DoReadPixels(int width, int height, unsigned char* rgb) {
-  if (!rgb) {
-    return;
-  }
-  if (framebuffer_mode_ == 0) {
-    mju_warning("ReadPixels is only supported for offscreen rendering.");
-    return;
-  }
-
-  const mjrRect viewport = {0, 0, width, height};
-  if (IsClassic(gfx_)) {
-    mjr_readPixels(rgb, nullptr, viewport, &render_context_);
-    mjr_setBuffer(mjFB_WINDOW, &render_context_);
-    FlipImage(rgb, viewport.width, viewport.height, 3);
-  } else {
-    mjrDrawMode draw_mode = mjDRAW_MODE_DEFAULT;
-    if (scene_.flags[mjRND_SEGMENT]) {
-      if (scene_.flags[mjRND_IDCOLOR]) {
-        draw_mode = mjDRAW_MODE_SEGMENTATION_BY_ID;
-      } else {
-        draw_mode = mjDRAW_MODE_SEGMENTATION_BY_COLOR;
-      }
-    } else if (scene_.flags[mjRND_DEPTH]) {
-      draw_mode = mjDRAW_MODE_DEPTH;
-    } else if (scene_.flags[mjRND_WIREFRAME]) {
-      draw_mode = mjDRAW_MODE_WIREFRAME;
-    }
-
-    mjrfRenderTargetConfig config;
-    mjrf_defaultRenderTargetConfig(&config);
-    config.width = viewport.width;
-    config.height = viewport.height;
-    config.color_format = mjPIXEL_FORMAT_RGB8;
-    config.depth_format = mjPIXEL_FORMAT_DEPTH32F;
-    auto target = CreateRenderTarget(filament_context_.get(), config);
-
-    mjrfRenderRequest reqs[2];
-    mjrf_defaultRenderRequest(&reqs[0]);
-    reqs[0].scene = main_scene_.get();
-    reqs[0].draw_mode = draw_mode;
-    reqs[0].camera = scene_bridge_->GetCamera();
-    reqs[0].target = target.get();
-    reqs[0].viewport = viewport;
-    reqs[0].enable_shadows = scene_.flags[mjRND_SHADOW];
-    reqs[0].enable_reflections = scene_.flags[mjRND_REFLECTION];
-
-    mjrf_defaultRenderRequest(&reqs[1]);
-    reqs[1].scene = ux_scene_.get();
-    reqs[1].draw_mode = mjDRAW_MODE_DEFAULT;
-    reqs[1].camera = imgui_bridge_->GetCamera(viewport.width, viewport.height);
-    reqs[1].target = target.get();
-    reqs[1].viewport = viewport;
-    reqs[1].enable_shadows = false;
-    reqs[1].enable_reflections = false;
-    reqs[1].enable_post_processing = false;
-
-    mjrfReadPixelsRequest read_request;
-    mjrf_defaultReadPixelsRequest(&read_request);
-    read_request.target = target.get();
-    read_request.output = rgb;
-    read_request.num_bytes = viewport.width * viewport.height * 3;
-
-    const int num_requests = (framebuffer_mode_ == 2) ? 2 : 1;
-    const mjrfFrameHandle frame = mjrf_render(
-        filament_context_.get(), &reqs[0], num_requests, &read_request, 1);
-    mjrf_waitForFrame(filament_context_.get(), frame);
-  }
-  DoSetBuffer(mjFB_WINDOW);
-}
-
-double Renderer::GetFps() { return fps_; }
-
-void Renderer::UpdateFps() {
-  if (IsClassic(gfx_)) {
-    TimePoint now = std::chrono::steady_clock::now();
-    TimePoint::duration delta_time = now - last_fps_update_;
-    const double interval = std::chrono::duration<double>(delta_time).count();
-    ++frames_;
-    if (interval > 0.2) {  // only update FPS stat at most 5 times per second
-      last_fps_update_ = now;
-      fps_ = frames_ / interval;
-      frames_ = 0;
-    }
-  } else {
-    mjrfFrameStats stats;
-    mjrf_defaultFrameStats(&stats);
-    mjrf_getFrameStats(filament_context_.get(), 0, &stats);
-    fps_ = stats.frame_rate;
-  }
-}
-
-}  // namespace mujoco::platform
-
-mjPLUGIN_LIB_INIT(renderer) {
-  mujoco::platform::GuiPlugin plugin;
-  plugin.name = "Filament";
-  plugin.update = [](mujoco::platform::GuiPlugin* self) {
-    mujoco::platform::PluginUpdate(self);
-  };
-  mujoco::platform::RegisterPlugin(plugin);
-}

src/experimental/platform/hal/renderer.h

@@ -15,117 +15,51 @@
 #ifndef MUJOCO_SRC_EXPERIMENTAL_PLATFORM_HAL_RENDERER_H_
 #define MUJOCO_SRC_EXPERIMENTAL_PLATFORM_HAL_RENDERER_H_
 
-#include <chrono>
 #include <cstddef>
-#include <memory>
-#include <ratio>
 #include <span>
 
-#include <mujoco/mjrfilament.h>
 #include <mujoco/mujoco.h>
-#include "experimental/filament/compat/scene_bridge.h"
-#include "experimental/platform/hal/graphics_mode.h"
-#include "experimental/platform/ux/imgui_bridge.h"
-#include "render/filament/mjrfilament_cpp.h"
 
 namespace mujoco::platform {
 
 // Renders the mujoco simulation and the imgui state.
-//
-// The Renderer is built around a specific backend configuration
-// (see renderer_backend.h).
-//
-// Currently we support two rendering engines: the Classic MuJoCo OpenGL
-// renderer and a Filament-based renderer.
-//
-// The Classic renderer is implemented using the OpenGL 2.0 fixed function
-// pipeline. It assumes that the caller has correctly initialized the OpenGL
-// context (e.g. using EGL).
-//
-// The Filament renderer is a modern physically-based renderer that supports
-// OpenGL 3.0, Vulkan, and WebGL (as well as other graphics libraries). Unlike
-// the Classic renderer, the Filament engine itself will manage its graphics
-// context. If rendering to a window surface (e.g. x11), it requires a pointer
-// to the native window to do so.
-//
-// For OpenGL, two different Filament configurations are available: normal and
-// headless. Normal rendering assumes that we will be rendering to an x11
-// window and therefore will use a x11-based context. Headless assumes that we
-// will be rendering to a texture and will use an EGL context. Vulkan and WebGL
-// have no need for such a distinction.
 class Renderer {
  public:
-  using Clock = std::chrono::steady_clock;
-  using TimePoint = std::chrono::time_point<Clock>;
-  using Seconds = std::chrono::duration<double>;
-  using Milliseconds = std::chrono::duration<double, std::milli>;
-
-  Renderer(void* native_window, GraphicsMode gfx_mode);
-  ~Renderer();
+  Renderer() = default;
+  virtual ~Renderer() = default;
 
   Renderer(const Renderer&) = delete;
   Renderer& operator=(const Renderer&) = delete;
 
   // Initializes the renderer with the given mjModel.
-  void Init(const mjModel* model);
+  virtual void Init(const mjModel* model) = 0;
 
   // Renders the simulation and ux state. Renders into `pixels` if provided,
   // otherwise renders to the `native_window` provided at construction.
-  void Render(const mjModel* model, mjData* data, const mjvPerturb* perturb,
-              mjvCamera* camera, const mjvOption* vis_option, int width,
-              int height, std::span<std::byte> pixels = {},
-              std::span<mjvGeom> extra_geoms = {});
+  virtual void Render(const mjModel* model, mjData* data,
+                      const mjvPerturb* perturb, mjvCamera* camera,
+                      const mjvOption* vis_option, int width, int height,
+                      std::span<std::byte> pixels = {},
+                      std::span<mjvGeom> extra_geoms = {}) = 0;
 
   // Populates the given output buffer with RGB888 pixel data. The size of the
   // output buffer must be at least width * height * 3.
-  void RenderToTexture(const mjModel* model, mjData* data, mjvCamera* camera,
-                       int width, int height, std::byte* output);
+  virtual void RenderToTexture(const mjModel* model, mjData* data,
+                               mjvCamera* camera, int width, int height,
+                               std::byte* output) = 0;
 
   // Uploads an image to the backend for GUI rendering, returning the texture
   // ID for the texture. The ID can be used in subsequent calls to update the
   // texture data. A nullptr pixels argument will free the texture if it exists.
   // A texture ID of 0 will create a new texture.
-  int UploadImage(int texture_id, const std::byte* pixels, int width,
-                  int height, int bpp);
+  virtual int UploadImage(int texture_id, const std::byte* pixels, int width,
+                          int height, int bpp) = 0;
 
   // Rendering flags.
-  mjtByte* GetRenderFlags() { return scene_.flags; }
+  virtual mjtByte* GetRenderFlags() = 0;
 
   // Returns the current frame rate.
-  double GetFps();
-
- private:
-  // Resets the renderer; no rendering will occur until Init() is called again.
-  void Deinit();
-
-  void UpdateFps();
-
-  void DoRender(int width, int height);
-  void DoSetBuffer(int framebuffer);
-  void DoReadPixels(int width, int height, unsigned char* rgb);
-
-  void* native_window_ = nullptr;
-  GraphicsMode gfx_ = GraphicsMode::FilamentVulkan;
-
-  // State used by the classic renderer.
-  std::shared_ptr<void> graphics_api_context_ = nullptr;
-  mjrContext render_context_;
-
-  // State used by the filament renderer.
-  UniquePtr<mjrfContext> filament_context_{nullptr, nullptr};
-  UniquePtr<mjrfScene> main_scene_{nullptr, nullptr};
-  UniquePtr<mjrfScene> ux_scene_{nullptr, nullptr};
-  std::unique_ptr<SceneBridge> scene_bridge_;
-  std::unique_ptr<ImguiBridge> imgui_bridge_;
-
-  // Common state.
-  int framebuffer_mode_ = 0;
-  mjvScene scene_;
-  bool initialized_ = false;
-  mjtNum last_update_time_ = -1;
-  int frames_ = 0;
-  TimePoint last_fps_update_;
-  double fps_ = 0;
+  virtual double GetFps() = 0;
 };
 
 }  // namespace mujoco::platform

src/experimental/platform/hal/renderer_test.cc

@@ -11,7 +11,7 @@
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
-#include "experimental/platform/hal/renderer.h"
+#include "experimental/platform/hal/filament_renderer.h"
 
 #include <cstddef>
 #include <memory>
@@ -50,7 +50,7 @@ class RendererTest : public ::testing::Test {
 };
 
 TEST_F(RendererTest, OpengGlSoftware) {
-  Renderer renderer(nullptr, GraphicsMode::FilamentOpenGlSoftware);
+  FilamentRenderer renderer(nullptr, GraphicsMode::FilamentOpenGlSoftware);
   renderer.Init(holder_->model());
 
   gl::DriverType driver_type = gl::GetLoadedDriverType();
@@ -69,7 +69,7 @@ TEST_F(RendererTest, OpengGlSoftware) {
 }
 
 TEST_F(RendererTest, OpengGlHeadless) {
-  Renderer renderer(nullptr, GraphicsMode::FilamentOpenGlHeadless);
+  FilamentRenderer renderer(nullptr, GraphicsMode::FilamentOpenGlHeadless);
   renderer.Init(holder_->model());
 
   gl::DriverType driver_type = gl::GetLoadedDriverType();
@@ -92,7 +92,7 @@ TEST_F(RendererTest, OpengGlHeadless) {
 }
 
 TEST_F(RendererTest, VulkanSoftware) {
-  Renderer renderer(nullptr, GraphicsMode::FilamentVulkanSoftware);
+  FilamentRenderer renderer(nullptr, GraphicsMode::FilamentVulkanSoftware);
   renderer.Init(holder_->model());
 
   std::vector<std::byte> pixels(width_ * height_ * 3);
@@ -108,7 +108,7 @@ TEST_F(RendererTest, VulkanSoftware) {
 }
 
 TEST_F(RendererTest, VulkanHeadless) {
-  Renderer renderer(nullptr, GraphicsMode::FilamentVulkan);
+  FilamentRenderer renderer(nullptr, GraphicsMode::FilamentVulkan);
   renderer.Init(holder_->model());
 
   std::vector<std::byte> pixels(width_ * height_ * 3);

src/experimental/studio/app.cc

@@ -36,6 +36,8 @@
 #include <imgui.h>
 #include <implot.h>
 #include <mujoco/mujoco.h>
+#include "experimental/platform/hal/classic_renderer.h"
+#include "experimental/platform/hal/filament_renderer.h"
 #include "experimental/platform/hal/graphics_mode.h"
 #include "experimental/platform/hal/renderer.h"
 #include "experimental/platform/hal/window.h"
@@ -119,8 +121,14 @@ void App::SwitchGraphicsMode(int width, int height,
   window_config.gfx_mode = gfx_mode_;
   window_ = std::make_unique<platform::Window>(app_title_, width, height,
                                                window_config);
-  renderer_ = std::make_unique<platform::Renderer>(
-      window_->GetNativeWindowHandle(), gfx_mode_);
+  if (platform::IsClassic(gfx_mode_)) {
+    renderer_ = std::make_unique<platform::ClassicRenderer>(
+        window_->GetNativeWindowHandle(), gfx_mode_);
+
+  } else {
+    renderer_ = std::make_unique<platform::FilamentRenderer>(
+        window_->GetNativeWindowHandle(), gfx_mode_);
+  }
 
   // TODO: Figure out why this breaks on some platforms.
   // LoadSettings();