Use mjResourceProvider instead of custom LoadAsset callbacks.

PiperOrigin-RevId: 853172824
Change-Id: I60ef1207611c4da119cc3f0a7819088cffca6e4f

src/experimental/platform/helpers.h

@@ -26,9 +26,6 @@
 
 namespace mujoco::platform {
 
-// Function signature for loading assets from a given path.
-using LoadAssetFn = std::function<std::vector<std::byte>(std::string_view)>;
-
 // Save/load for simple ascii files.
 void SaveText(const std::string& contents, const std::string& filename);
 std::string LoadText(const std::string& filename);

src/experimental/platform/renderer.cc

@@ -14,17 +14,9 @@
 
 #include "experimental/platform/renderer.h"
 
-#include <chrono>
-#include <cstddef>
-#include <cstdint>
-#include <cstdlib>
-#include <cstring>
-#include <vector>
-
 #include <cstddef>
 
 #include <mujoco/mujoco.h>
-#include "experimental/platform/helpers.h"
 
 #if defined(USE_FILAMENT_OPENGL) || defined(USE_FILAMENT_VULKAN)
 #include "experimental/filament/render_context_filament.h"
@@ -37,8 +29,7 @@
 
 namespace mujoco::platform {
 
-Renderer::Renderer(void* native_window, const LoadAssetFn& load_asset_fn)
-    : load_asset_fn_(load_asset_fn), native_window_(native_window) {
+Renderer::Renderer(void* native_window) : native_window_(native_window) {
 #ifdef USE_CLASSIC_OPENGL
   ImGui_ImplOpenGL3_Init();
 #endif
@@ -57,8 +48,6 @@ void Renderer::Init(const mjModel* model) {
     mjrFilamentConfig render_config;
     mjr_defaultFilamentConfig(&render_config);
     render_config.native_window = native_window_;
-    render_config.load_asset = &Renderer::LoadAssetCallback;
-    render_config.load_asset_user_data = this;
     render_config.enable_gui = true;
 #if defined(USE_FILAMENT_OPENGL)
     render_config.graphics_api = mjGFX_OPENGL;
@@ -140,23 +129,4 @@ void Renderer::RenderToTexture(const mjModel* model, mjData* data,
 
 double Renderer::GetFps() { return fps_; }
 
-int Renderer::LoadAssetCallback(const char* path, void* user_data,
-                                unsigned char** out, std::uint64_t* out_size) {
-  Renderer* renderer = static_cast<Renderer*>(user_data);
-  std::vector<std::byte> bytes = (renderer->load_asset_fn_)(path);
-  if (bytes.empty()) {
-    *out_size = 0;
-    return 0;  // Empty file
-  }
-
-  *out_size = bytes.size();
-  *out = reinterpret_cast<unsigned char*>(malloc(*out_size));
-  if (*out == nullptr) {
-    mju_error("Failed to allocate memory for file %s", path);
-    return -1;
-  }
-
-  std::memcpy(*out, bytes.data(), *out_size);
-  return 0;
-}
 }  // namespace mujoco::platform

src/experimental/platform/renderer.h

@@ -17,11 +17,9 @@
 
 #include <chrono>
 #include <cstddef>
-#include <cstdint>
 #include <ratio>
 
 #include <mujoco/mujoco.h>
-#include "experimental/platform/helpers.h"
 
 namespace mujoco::platform {
 
@@ -34,7 +32,7 @@ class Renderer {
   using Seconds = std::chrono::duration<double>;
   using Milliseconds = std::chrono::duration<double, std::milli>;
 
-  Renderer(void* native_window, const LoadAssetFn& load_asset_fn);
+  explicit Renderer(void* native_window);
   ~Renderer();
 
   Renderer(const Renderer&) = delete;
@@ -64,10 +62,6 @@ class Renderer {
   // Resets the renderer; no rendering will occur until Init() is called again.
   void Deinit();
 
-  static int LoadAssetCallback(const char* path, void* user_data,
-                               unsigned char** out, std::uint64_t* out_size);
-
-  LoadAssetFn load_asset_fn_;
   void* native_window_ = nullptr;
   mjrContext render_context_;
   mjvScene scene_;

src/experimental/platform/window.cc

@@ -26,8 +26,8 @@
 #include <SDL_video.h>
 #include <backends/imgui_impl_sdl2.h>
 #include <imgui.h>
-#include "experimental/platform/helpers.h"
 #include <mujoco/mujoco.h>
+#include "user/user_resource.h"
 
 // Because X11/Xlib.h defines Status.
 #ifdef Status
@@ -40,8 +40,7 @@ extern void* GetNativeWindowOsx(void* window);
 
 namespace mujoco::platform {
 
-static void InitImGui(SDL_Window* window, const LoadAssetFn& load_asset_fn,
-                      bool load_fonts, bool build_fonts) {
+static void InitImGui(SDL_Window* window, bool load_fonts, bool build_fonts) {
   ImGui::CreateContext();
 
   ImGuiIO& io = ImGui::GetIO();
@@ -52,28 +51,36 @@ static void InitImGui(SDL_Window* window, const LoadAssetFn& load_asset_fn,
   ImGui_ImplSDL2_InitForOther(window);
 
   if (load_fonts) {
-    // Note: fonts are stored statically because they aren't actually loaded
-    // until the fonts are built.
+    mjResource* font = nullptr;
+    int size = 0;
+    void* data = nullptr;
+
     ImFontConfig main_cfg;
-    static auto main_font = load_asset_fn("OpenSans-Regular.ttf");
-    io.Fonts->AddFontFromMemoryTTF(main_font.data(), main_font.size(), 20.f,
-                                  &main_cfg);
+    main_cfg.FontDataOwnedByAtlas = false;
+    font =
+        mju_openResource("", "font:OpenSans-Regular.ttf", nullptr, nullptr, 0);
+    size = mju_readResource(font, const_cast<const void**>(&data));
+    io.Fonts->AddFontFromMemoryTTF(data, size, 20.f, &main_cfg);
 
     ImFontConfig icon_cfg;
+    icon_cfg.FontDataOwnedByAtlas = false;
     icon_cfg.MergeMode = true;
-    static auto icon_font = load_asset_fn("fontawesome-webfont.ttf");
+    font = mju_openResource("", "font:fontawesome-webfont.ttf", nullptr,
+                            nullptr, 0);
+    size = mju_readResource(font, const_cast<const void**>(&data));
     constexpr ImWchar icon_ranges[] = {0xf000, 0xf3ff, 0x000};
-    io.Fonts->AddFontFromMemoryTTF(icon_font.data(), icon_font.size(), 14.f,
-                                  &icon_cfg, icon_ranges);
+    io.Fonts->AddFontFromMemoryTTF(data, size, 14.f, &icon_cfg, icon_ranges);
 
     if (build_fonts) {
       io.Fonts->Build();
     }
+
+    // Note: we purposefully do not "close" the font resources as ImGui may
+    // need them again to resize fonts.
   }
 }
 
-Window::Window(std::string_view title, int width, int height, Config config,
-               const LoadAssetFn& load_asset_fn)
+Window::Window(std::string_view title, int width, int height, Config config)
     : width_(width), height_(height), config_(config) {
   SDL_SetHint(SDL_HINT_FRAMEBUFFER_ACCELERATION, "1");
   SDL_GL_SetAttribute(SDL_GL_MULTISAMPLEBUFFERS, 1);
@@ -113,8 +120,7 @@ Window::Window(std::string_view title, int width, int height, Config config,
     mju_error("Error creating window: %s", SDL_GetError());
   }
 
-  InitImGui(sdl_window_, load_asset_fn, config.load_fonts,
-            (render_config != kClassicOpenGL));
+  InitImGui(sdl_window_, config.load_fonts, (render_config != kClassicOpenGL));
 
   if (render_config == kFilamentWebGL || render_config == kClassicOpenGL) {
     SDL_GLContext gl_context = SDL_GL_CreateContext(sdl_window_);

src/experimental/platform/window.h

@@ -43,8 +43,7 @@ class Window {
     bool load_fonts = true;
   };
 
-  Window(std::string_view title, int width, int height, Config config,
-         const LoadAssetFn& load_asset_fn);
+  Window(std::string_view title, int width, int height, Config config);
   ~Window();
 
   Window(const Window&) = delete;