feat(示例): 添加文字渲染示例并修复场景过渡方法声明

添加新的文字渲染示例 demo_text_rendering，展示如何使用 GLFontAtlas 渲染文字
修复场景过渡类中缺少 override 关键字的方法声明
更新 README 文档以包含新示例

Extra2D/include/extra2d/scene/transition_box_scene.h

@@ -26,7 +26,7 @@ public:
 protected:
   void onTransitionStart() override;
   void renderContent(RenderBackend &renderer) override;
-  void updateTransition(float dt);
+  void updateTransition(float dt) override;
 
 private:
   int divisions_;

Extra2D/include/extra2d/scene/transition_flip_scene.h

@@ -29,7 +29,7 @@ public:
 protected:
   void onTransitionStart() override;
   void renderContent(RenderBackend &renderer) override;
-  void updateTransition(float dt);
+  void updateTransition(float dt) override;
 
 private:
   Axis axis_;

Extra2D/include/extra2d/scene/transition_scale_scene.h

@@ -24,7 +24,7 @@ public:
 protected:
   void onTransitionStart() override;
   void renderContent(RenderBackend &renderer) override;
-  void updateTransition(float dt);
+  void updateTransition(float dt) override;
 };
 
 } // namespace extra2d

Extra2D/include/extra2d/scene/transition_slide_scene.h

@@ -27,7 +27,7 @@ public:
 protected:
   void onTransitionStart() override;
   void renderContent(RenderBackend &renderer) override;
-  void updateTransition(float dt);
+  void updateTransition(float dt) override;
 
 private:
   TransitionDirection direction_;

README.md

@@ -407,6 +407,7 @@ eventService->addListener(EventType::GamepadButtonPressed, [](Event& e) {
 | 示例 | 说明 |
 |-----|------|
 | `demo_basic` | 基础示例：场景图、输入事件、视口适配 |
+| `demo_text_rendering` | 文字渲染示例：使用 GLFontAtlas 渲染文字 |
 
 运行示例：
 

examples/text_rendering/main.cpp

@@ -0,0 +1,206 @@
+/**
+ * @file main.cpp
+ * @brief Extra2D 文字渲染示例
+ *
+ * 演示如何使用 GLFontAtlas 渲染文字
+ */
+
+#include <extra2d/core/service_locator.h>
+#include <extra2d/extra2d.h>
+#include <extra2d/graphics/backends/opengl/gl_font_atlas.h>
+#include <extra2d/graphics/backends/opengl/gl_renderer.h>
+#include <extra2d/graphics/core/render_module.h>
+#include <extra2d/graphics/texture/font.h>
+#include <extra2d/platform/input_module.h>
+#include <extra2d/platform/window_module.h>
+#include <extra2d/services/camera_service.h>
+#include <extra2d/services/event_service.h>
+#include <iostream>
+
+using namespace extra2d;
+
+class TextRenderingScene : public Scene {
+public:
+  void onEnter() override {
+    // 加载字体
+    // 注意：请确保有字体文件在 assets/fonts/ 目录下
+    // 如果没有，可以使用系统字体路径
+    try {
+      font_ = std::make_shared<GLFontAtlas>("assets/fonts/arial.ttf", 24);
+    } catch (...) {
+      std::cerr << "Failed to load font from assets/fonts/arial.ttf"
+                << std::endl;
+      // 尝试使用备用路径
+      try {
+        font_ = std::make_shared<GLFontAtlas>("C:/Windows/Fonts/arial.ttf", 24);
+      } catch (...) {
+        std::cerr << "Failed to load font from system path!" << std::endl;
+        font_ = nullptr;
+      }
+    }
+
+    if (font_) {
+      std::cout << "Font loaded successfully!" << std::endl;
+      std::cout << "  Font size: " << font_->getFontSize() << std::endl;
+      std::cout << "  Line height: " << font_->getLineHeight() << std::endl;
+      std::cout << "  Ascent: " << font_->getAscent() << std::endl;
+      std::cout << "  Descent: " << font_->getDescent() << std::endl;
+    }
+  }
+
+  void onExit() override { font_.reset(); }
+
+  void onRender(RenderBackend &renderer) override {
+    Scene::onRender(renderer);
+
+    if (!font_) {
+      return;
+    }
+
+    // 获取渲染器
+    auto *glRenderer = dynamic_cast<GLRenderer *>(&renderer);
+    if (!glRenderer) {
+      return;
+    }
+
+    // 开始精灵批处理
+    glRenderer->beginSpriteBatch();
+
+    float y = 100.0f;
+    float x = 100.0f;
+
+    // 渲染标题
+    renderText(glRenderer, "Extra2D Text Rendering Demo", x, y,
+               Color(1.0f, 0.8f, 0.2f, 1.0f));
+    y += font_->getLineHeight() * 2;
+
+    // 渲染不同颜色的文字
+    renderText(glRenderer, "Red Text", x, y, Color(1.0f, 0.2f, 0.2f, 1.0f));
+    y += font_->getLineHeight();
+
+    renderText(glRenderer, "Green Text", x, y, Color(0.2f, 1.0f, 0.2f, 1.0f));
+    y += font_->getLineHeight();
+
+    renderText(glRenderer, "Blue Text", x, y, Color(0.2f, 0.2f, 1.0f, 1.0f));
+    y += font_->getLineHeight() * 2;
+
+    // 渲染多行文字
+    renderText(glRenderer, "This is a multi-line text example.", x, y,
+               Color(1.0f, 1.0f, 1.0f, 1.0f));
+    y += font_->getLineHeight();
+    renderText(glRenderer, "You can render text with different colors", x, y,
+               Color(0.8f, 0.8f, 0.8f, 1.0f));
+    y += font_->getLineHeight();
+    renderText(glRenderer, "and styles using GLFontAtlas.", x, y,
+               Color(0.6f, 0.6f, 0.6f, 1.0f));
+    y += font_->getLineHeight() * 2;
+
+    // 渲染半透明文字
+    renderText(glRenderer, "Semi-transparent text (50% opacity)", x, y,
+               Color(1.0f, 1.0f, 1.0f, 0.5f));
+    y += font_->getLineHeight() * 2;
+
+    // 渲染操作提示
+    renderText(glRenderer, "Press ESC to exit", x, y,
+               Color(0.5f, 0.5f, 0.5f, 1.0f));
+
+    // 结束精灵批处理
+    glRenderer->endSpriteBatch();
+  }
+
+private:
+  void renderText(GLRenderer *renderer, const std::string &text, float x,
+                  float y, const Color &color) {
+    if (!font_ || !renderer) {
+      return;
+    }
+
+    // 使用渲染器的 drawText 方法
+    renderer->drawText(*font_, text, Vec2(x, y), color);
+  }
+
+  std::shared_ptr<GLFontAtlas> font_;
+};
+
+int main(int argc, char *argv[]) {
+  (void)argc;
+  (void)argv;
+
+  std::cout << "Extra2D Text Rendering Demo - Starting..." << std::endl;
+
+  Application &app = Application::get();
+
+  // 注册模块
+  app.use<WindowModule>([](auto &cfg) {
+    cfg.w = 1280;
+    cfg.h = 720;
+    cfg.title = "Extra2D Text Rendering Demo";
+    cfg.priority = 0;
+    cfg.backend = "glfw";
+  });
+
+  app.use<RenderModule>([](auto &cfg) { cfg.priority = 10; });
+
+  app.use<InputModule>([](auto &cfg) { cfg.priority = 20; });
+
+  std::cout << "Initializing application..." << std::endl;
+  if (!app.init()) {
+    std::cerr << "Failed to initialize application!" << std::endl;
+    return -1;
+  }
+
+  std::cout << "Application initialized successfully!" << std::endl;
+
+  auto *win = app.window();
+  if (win) {
+    std::cout << "Window: " << win->width() << "x" << win->height()
+              << std::endl;
+  }
+
+  // 设置事件监听
+  auto eventService = ServiceLocator::instance().getService<IEventService>();
+  if (eventService) {
+    eventService->addListener(EventType::KeyPressed, [](Event &e) {
+      auto &keyEvent = std::get<KeyEvent>(e.data);
+      if (keyEvent.keyCode == static_cast<int>(Key::Escape)) {
+        e.handled = true;
+        Application::get().quit();
+      }
+    });
+  }
+
+  // 创建并配置场景
+  auto scene = makeShared<TextRenderingScene>();
+  scene->setBackgroundColor(Color(0.1f, 0.1f, 0.15f, 1.0f));
+
+  if (win) {
+    scene->setViewportSize(static_cast<float>(win->width()),
+                           static_cast<float>(win->height()));
+  }
+
+  // 配置相机
+  auto cameraService = ServiceLocator::instance().getService<ICameraService>();
+  if (cameraService && win) {
+    ViewportConfig vpConfig;
+    vpConfig.logicWidth = static_cast<float>(win->width());
+    vpConfig.logicHeight = static_cast<float>(win->height());
+    vpConfig.mode = ViewportMode::AspectRatio;
+    cameraService->setViewportConfig(vpConfig);
+    cameraService->updateViewport(win->width(), win->height());
+    cameraService->applyViewportAdapter();
+  }
+
+  app.enterScene(scene);
+
+  std::cout << "\nControls:" << std::endl;
+  std::cout << "  ESC - Exit" << std::endl;
+  std::cout << "\nRunning main loop...\n" << std::endl;
+
+  app.run();
+
+  std::cout << "Shutting down..." << std::endl;
+  app.shutdown();
+
+  std::cout << "Goodbye!" << std::endl;
+  return 0;
+}

xmake.lua

@@ -202,6 +202,65 @@ target("demo_basic")
     after_build(install_shaders)
 target_end()
 
+-- 文字渲染示例
+target("demo_text_rendering")
+    set_kind("binary")
+    set_default(false)
+    
+    add_deps("extra2d")
+    add_files("examples/text_rendering/main.cpp")
+    
+    -- 平台配置
+    local plat = get_config("plat") or os.host()
+    local backend = get_config("window_backend") or "sdl2"
+    if plat == "mingw" or plat == "windows" then
+        add_packages("glm", "nlohmann_json")
+        if backend == "glfw" then
+            add_packages("glfw")
+        else
+            add_packages("libsdl2")
+        end
+        add_syslinks("opengl32", "glu32", "winmm", "imm32", "version", "setupapi")
+    elseif plat == "linux" then
+        add_packages("glm", "nlohmann_json")
+        if backend == "glfw" then
+            add_packages("glfw")
+        else
+            add_packages("libsdl2")
+        end
+        add_syslinks("GL", "dl", "pthread")
+    elseif plat == "macosx" then
+        add_packages("glm", "nlohmann_json")
+        if backend == "glfw" then
+            add_packages("glfw")
+        else
+            add_packages("libsdl2")
+        end
+        add_frameworks("OpenGL", "Cocoa", "IOKit", "CoreVideo")
+    end
+    
+    -- 构建后安装Shader文件和assets
+    after_build(function (target)
+        -- 安装shaders
+        local plat = get_config("plat") or os.host()
+        local targetdir = target:targetdir()
+        local shader_src = "Extra2D/shaders"
+        local shader_dest = path.join(targetdir, "shaders")
+        os.rm(shader_dest)
+        os.cp(shader_src, shader_dest)
+        print("Shaders installed to: " .. shader_dest)
+        
+        -- 复制assets目录
+        local assets_src = "examples/text_rendering/assets"
+        local assets_dest = path.join(targetdir, "assets")
+        if os.exists(assets_src) then
+            os.rm(assets_dest)
+            os.cp(assets_src, assets_dest)
+            print("Assets installed to: " .. assets_dest)
+        end
+    end)
+target_end()
+
 -- Hello Module 示例 - 展示如何创建自定义模块
 target("demo_hello_module")
     set_kind("binary")