多版本兼容方案：Cocos2d-x游戏同时支持HarmonyOS 4与5的渲染后端切换

以下为 ​​Cocos2d-x游戏同时兼容HarmonyOS 4与5的渲染后端切换方案​​，包含版本检测、动态接口适配和渲染管线切换的核心代码实现：

---

1. 版本检测与能力查询

1.1 系统版本识别

// version-detector.ets
class HarmonyVersion {
  private static readonly MIN_HOS5 = 5000000; // API Level 50+

  static isHarmonyOS5(): boolean {
    return device.apiLevel >= this.MIN_HOS5;
  }

  static getGraphicsCapabilities(): GraphicsFeature[] {
    return device.graphics.features.filter(feat => 
      this.isHarmonyOS5() ? true : feat.supportInHOS4
    );
  }
}

1.2 特性兼容检查

// feature-checker.ets
class RenderFeatureValidator {
  static checkRequiredFeatures(): void {
    const required = ['vk1.1', 'astc', 'compute_shaders'];
    const missing = required.filter(f => 
      !device.graphics.features.includes(f)
    );
    if (missing.length > 0) {
      throw new Error(`缺失必要特性: ${missing.join(',')}`);
    }
  }
}

---

2. 动态渲染后端切换

2.1 渲染器工厂

// renderer-factory.ets
class RenderBackendFactory {
  static createRenderer(): Renderer {
    return HarmonyVersion.isHarmonyOS5() ? 
      this._createVulkanRenderer() : 
      this._createGLESRenderer();
  }

  private static _createVulkanRenderer(): Renderer {
    return new VulkanRenderer({
      maxFramesInFlight: 2,
      enableAsyncCompute: true
    });
  }

  private static _createGLESRenderer(): Renderer {
    return new GLESRenderer({
      version: '3.2',
      extensions: ['EXT_color_buffer_float']
    });
  }
}

2.2 着色器变体管理

// shader-variant.ets
class ShaderVariantManager {
  static getShaderSource(name: string): string {
    const baseSource = assets.loadShader(name);
    return HarmonyVersion.isHarmonyOS5() ?
      `#define VULKAN\n${baseSource}` :
      `#define GLES\n${baseSource}`;
  }
}

---

3. 运行时管线切换

3.1 渲染指令转换层

// command-converter.ets
class RenderCommandTranslator {
  static convert(command: RenderCommand): BackendCommand {
    return HarmonyVersion.isHarmonyOS5() ?
      this._toVulkanCommand(command) :
      this._toGLESCommand(command);
  }

  private static _toVulkanCommand(cmd: RenderCommand): VulkanCommand {
    return {
      type: cmd.type === 'draw' ? 'vkCmdDraw' : 'vkCmdDispatch',
      params: cmd.params
    };
  }
}

3.2 纹理格式适配

// texture-adapter.ets
class TextureFormatAdapter {
  static getOptimalFormat(): TextureFormat {
    return HarmonyVersion.isHarmonyOS5() ?
      'ASTC_4x4' :
      'ETC2_RGBA';
  }

  static convertTexture(texture: Texture): void {
    const targetFormat = this.getOptimalFormat();
    if (texture.format !== targetFormat) {
      texture.recompress(targetFormat);
    }
  }
}

---

4. 完整工作流示例

4.1 游戏启动初始化

// game-init.ets
class GraphicsInitializer {
  static async init(): Promise<void> {
    // 1. 检查系统版本和能力
    RenderFeatureValidator.checkRequiredFeatures();
    
    // 2. 创建对应渲染器
    const renderer = RenderBackendFactory.createRenderer();
    
    // 3. 转换所有纹理
    TextureManager.getAllTextures().forEach(texture => 
      TextureFormatAdapter.convertTexture(texture)
    );
    
    // 4. 启动渲染循环
    renderer.start();
  }
}

4.2 帧渲染适配

// render-adapter.ets
class FrameRenderer {
  private static renderer?: Renderer;

  static render(scene: Scene): void {
    if (!this.renderer) {
      this.renderer = RenderBackendFactory.createRenderer();
    }
    
    const commands = scene.getRenderCommands();
    const translated = commands.map(cmd => 
      RenderCommandTranslator.convert(cmd)
    );
    
    this.renderer.submit(translated);
  }
}

---

5. 关键兼容性指标

特性	HarmonyOS 4支持	HarmonyOS 5支持	降级方案
Vulkan 1.1	❌	✅	回退到OpenGL ES 3.2
ASTC纹理压缩	仅部分设备	✅	使用ETC2
计算着色器	❌	✅	CPU模拟
多视图渲染	❌	✅	单通道渲染

---

6. 生产环境配置

6.1 渲染参数预设

// render-presets.json
{
  "hos4": {
    "graphicsAPI": "gles3",
    "textureFormat": "ETC2",
    "maxLights": 8,
    "shadowQuality": "low"
  },
  "hos5": {
    "graphicsAPI": "vulkan",
    "textureFormat": "ASTC",
    "maxLights": 32,
    "shadowQuality": "high"
  }
}

6.2 性能适配策略

// performance-policy.ets
class RenderQualityPolicy {
  static getSettings(): RenderSettings {
    return HarmonyVersion.isHarmonyOS5() ? 
      this._hos5Settings() : 
      this._hos4Settings();
  }

  private static _hos5Settings(): RenderSettings {
    return {
      msaa: 4,
      particleMax: 5000,
      textureQuality: 'high'
    };
  }
}

---

7. 扩展能力

7.1 动态功能降级

// feature-fallback.ets
class FeatureFallbackHandler {
  static handleUnsupported(feature: string): void {
    const fallbacks = {
      'ray_query': () => this._fallbackToSDF(),
      'mesh_shader': () => this._fallbackToVertexShader()
    };
    fallbacks[feature]?.();
  }
}

7.2 多版本着色器热加载

// shader-hotload.ets
class ShaderHotReloader {
  static async reload(name: string): Promise<void> {
    const source = ShaderVariantManager.getShaderSource(name);
    const program = HarmonyVersion.isHarmonyOS5() ?
      await VulkanCompiler.compile(source) :
      await GLESCompiler.compile(source);
    
    MaterialManager.updateShader(name, program);
  }
}

---

8. 调试工具集成

8.1 渲染器信息面板

// renderer-debug.ets
@Component
struct RendererInfoView {
  @State info: RendererInfo = {};

  build() {
    Column() {
      Text(`渲染后端: ${this.info.backend}`)
      Text(`API版本: ${this.info.version}`)
      Text(`活动特性: ${this.info.features.join(',')}`)
    }
    .onRendererInit(info => this.info = info)
  }
}

8.2 性能对比工具

// perf-comparator.ets
class RenderPerfComparator {
  static compare(): void {
    const glPerf = this._testGLESPerformance();
    const vkPerf = this._testVulkanPerformance();
    
    console.table({
      '平均帧率': [glPerf.fps, vkPerf.fps],
      'Draw Calls': [glPerf.drawCalls, vkPerf.drawCalls],
      '显存占用': [`${glPerf.vram}MB`, `${vkPerf.vram}MB`]
    });
  }
}

---

通过本方案可实现：

1. ​​自动检测​​ 系统版本
2. ​​无缝切换​​ 渲染后端
3. ​​智能降级​​ 高级特性
4. ​​统一接口​​ 兼容多版本