feat(shader): 支持单文件分段着色器并更新内置默认着色器

- 扩展 ShaderLoader 以支持 .glsl 单文件分段格式（#type vertex/fragment）
- 将内置默认着色器从分离的 .vert/.frag 文件合并为单个 default.glsl 文件
- 更新 BuiltinAssetFactory 使用新的加载方式创建默认着色器
- 删除旧的 default.frag 文件，简化着色器资源管理

include/assets/loaders/shader_loader.h

@@ -17,7 +17,7 @@ public:
     explicit ShaderLoader(AssetFileSystem fileSystem);
     /**
      * @brief 从文件加载着色器
-     * @param path 单个文件路径（自动推断 .vert/.frag）
+     * @param path 单个文件路径（.glsl 单文件分段，或自动推断 .vert/.frag）
      * @return 着色器指针，失败返回 nullptr
      */
     Ptr<Shader> load(const std::string& path) override;

shader/default.frag

@@ -1,40 +0,0 @@
-#version 320 es
-precision highp float;
-
-// 从顶点着色器输入
-in vec2 vTexCoord;
-in vec4 vColor;
-in vec4 vTintColor;
-in float vOpacity;
-
-// 纹理采样器
-uniform sampler2D uTexture;
-
-// 输出颜色
-out vec4 fragColor;
-
-/**
- * @brief 片段着色器入口
- *
- * 采样纹理并与顶点颜色、色调和透明度混合
- */
-void main() {
-    // 采样纹理
-    vec4 texColor = texture(uTexture, vTexCoord);
-    
-    // 如果纹理采样结果是黑色或透明，使用白色作为默认值
-    if (texColor.rgb == vec3(0.0) || texColor.a < 0.01) {
-        texColor = vec4(1.0, 1.0, 1.0, 1.0);
-    }
-    
-    // 混合：纹理 * 顶点颜色 * 色调
-    fragColor = texColor * vColor * vTintColor;
-    
-    // 应用透明度
-    fragColor.a *= vOpacity;
-    
-    // Alpha 测试：丢弃几乎透明的像素
-    if (fragColor.a < 0.01) {
-        discard;
-    }
-}

shader/default.glsl

@@ -1,7 +1,7 @@
+#type vertex
 #version 320 es
 precision highp float;
 
-// 全局 UBO (binding = 0) - 每帧更新一次
 layout(std140, binding = 0) uniform GlobalUBO {
     mat4 uViewProjection;
     vec4 uCameraPosition;
@@ -10,39 +10,56 @@ layout(std140, binding = 0) uniform GlobalUBO {
     vec2 uScreenSize;
 };
 
-// 材质 UBO (binding = 1) - 每物体更新
 layout(std140, binding = 1) uniform MaterialUBO {
     vec4 uColor;
     vec4 uTintColor;
     float uOpacity;
-    float uPadding[3];  // std140 对齐填充
+    float uPadding[3];
 };
 
-// 模型矩阵作为单独的统一变量（每个物体设置）
 uniform mat4 uModelMatrix;
 
-// 顶点属性
 layout(location = 0) in vec2 aPosition;
 layout(location = 1) in vec2 aTexCoord;
 layout(location = 2) in vec4 aColor;
 
-// 输出到片段着色器
 out vec2 vTexCoord;
 out vec4 vColor;
 out vec4 vTintColor;
 out float vOpacity;
 
-/**
- * @brief 顶点着色器入口
- *
- * 计算顶点在裁剪空间中的位置，
- * 并传递纹理坐标和颜色到片段着色器
- */
 void main() {
     gl_Position = uViewProjection * uModelMatrix * vec4(aPosition, 0.0, 1.0);
     vTexCoord = aTexCoord;
-    // 混合顶点颜色和材质 UBO 中的颜色
     vColor = aColor * uColor;
     vTintColor = uTintColor;
     vOpacity = uOpacity;
 }
+
+#type fragment
+#version 320 es
+precision highp float;
+
+in vec2 vTexCoord;
+in vec4 vColor;
+in vec4 vTintColor;
+in float vOpacity;
+
+uniform sampler2D uTexture;
+
+out vec4 fragColor;
+
+void main() {
+    vec4 texColor = texture(uTexture, vTexCoord);
+
+    if (texColor.rgb == vec3(0.0) || texColor.a < 0.01) {
+        texColor = vec4(1.0, 1.0, 1.0, 1.0);
+    }
+
+    fragColor = texColor * vColor * vTintColor;
+    fragColor.a *= vOpacity;
+
+    if (fragColor.a < 0.01) {
+        discard;
+    }
+}

src/assets/builtin/builtin_asset_factory.cpp

@@ -1,4 +1,5 @@
 #include <assets/builtin/builtin_asset_factory.h>
+#include <assets/loaders/shader_loader.h>
 #include <utils/logger.h>
 
 namespace extra2d {
@@ -22,18 +23,9 @@ bool BuiltinAssetFactory::create() {
   }
 
   {
-    std::string vertPath = fileSystem_.assetPath("shader/default.vert");
+    ShaderLoader shaderLoader(fileSystem_);
-    std::string fragPath = fileSystem_.assetPath("shader/default.frag");
+    Ptr<Shader> shader = shaderLoader.load("shader/default.glsl");
-    if (!fileSystem_.exists(vertPath) || !fileSystem_.exists(fragPath)) {
+    if (!shader) {
-      return false;
-    }
-    std::string vsSource = fileSystem_.readString(vertPath);
-    std::string fsSource = fileSystem_.readString(fragPath);
-    if (vsSource.empty() || fsSource.empty()) {
-      return false;
-    }
-    Ptr<Shader> shader = makePtr<Shader>();
-    if (!shader->loadFromSource(vsSource, fsSource)) {
       return false;
     }
     defaultShader_ = shaders_.insert(shader);
@@ -92,4 +84,3 @@ Handle<Material> BuiltinAssetFactory::defaultMaterial() const {
 Handle<Mesh> BuiltinAssetFactory::defaultQuad() const { return defaultQuad_; }
 
 } // namespace extra2d
-

src/assets/loaders/shader_loader.cpp

@@ -1,16 +1,91 @@
 #include <assets/loaders/shader_loader.h>
 #include <renderer/shader.h>
 #include <utils/logger.h>
+#include <sstream>
 
 namespace extra2d {
+namespace {
+
+enum class ShaderStageType {
+    None,
+    Vertex,
+    Fragment
+};
+
+static bool parseCombinedShaderSource(const std::string& source,
+                                      std::string& vsSource,
+                                      std::string& fsSource) {
+    std::istringstream stream(source);
+    std::string line;
+    ShaderStageType stage = ShaderStageType::None;
+
+    while (std::getline(stream, line)) {
+        const size_t first = line.find_first_not_of(" \t");
+        std::string trimmed = first == std::string::npos ? "" : line.substr(first);
+
+        if (!trimmed.empty() && (trimmed.rfind("#type", 0) == 0 || trimmed.rfind("#shader", 0) == 0)) {
+            std::istringstream directive(trimmed);
+            std::string key;
+            std::string value;
+            directive >> key >> value;
+
+            if (value == "vertex" || value == "vert" || value == "vs") {
+                stage = ShaderStageType::Vertex;
+            } else if (value == "fragment" || value == "frag" || value == "fs") {
+                stage = ShaderStageType::Fragment;
+            } else {
+                stage = ShaderStageType::None;
+            }
+            continue;
+        }
+
+        if (stage == ShaderStageType::Vertex) {
+            vsSource += line + "\n";
+        } else if (stage == ShaderStageType::Fragment) {
+            fsSource += line + "\n";
+        }
+    }
+
+    return !vsSource.empty() && !fsSource.empty();
+}
+
+}
 
 ShaderLoader::ShaderLoader(AssetFileSystem fileSystem)
     : fileSystem_(std::move(fileSystem)) {}
 
 Ptr<Shader> ShaderLoader::load(const std::string &path) {
+  std::string::size_type dotPos = path.rfind('.');
+  if (dotPos != std::string::npos) {
+    std::string ext = path.substr(dotPos);
+    if (ext == ".glsl") {
+      std::string source = fileSystem_.readString(path);
+      if (source.empty()) {
+        E2D_ERROR("ShaderLoader: 读取着色器失败: {}", path);
+        return Ptr<Shader>();
+      }
+
+      std::string vsSource;
+      std::string fsSource;
+      if (!parseCombinedShaderSource(source, vsSource, fsSource)) {
+        E2D_ERROR("ShaderLoader: 单文件着色器缺少分段标记(#type vertex/#type fragment): {}", path);
+        return Ptr<Shader>();
+      }
+
+      Ptr<Shader> shader = makePtr<Shader>();
+      if (!shader->loadFromSource(vsSource, fsSource)) {
+        E2D_ERROR("ShaderLoader: 编译单文件着色器失败 {}", path);
+        return Ptr<Shader>();
+      }
+
+      E2D_DEBUG("ShaderLoader: 已加载单文件着色器 {}", path);
+      return shader;
+    }
+  }
+
   std::string basePath = path;
 
-  std::string::size_type dotPos = basePath.rfind('.');
+  dotPos = basePath.rfind('.');
   if (dotPos != std::string::npos) {
     basePath = basePath.substr(0, dotPos);
   }