�?3.4章：渲染纹理技�?

渲染纹理(Render Texture)是现代图形编程中的核心技术，允许我们将场景渲染到纹理中进行后续处理。本教程将深入讲解渲染纹理的原理、实现和各种应用场景�?

🎯 学习目标

  • 理解渲染纹理和FBO的工作原�?- 掌握Cocos Creator中的渲染纹理实现
  • 学会实现后处理效果和屏幕空间技�?- 了解渲染纹理的性能优化策略

🔧 渲染纹理基础

FBO基础概念

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// 帧缓冲对�?FBO)管理�?class FrameBufferManager {
    private gl: WebGL2RenderingContext;
    private frameBuffers: Map<string, FrameBufferObject> = new Map();
    
    interface FrameBufferObject {
        fbo: WebGLFramebuffer;
        colorTextures: WebGLTexture[];
        depthTexture?: WebGLTexture;
        depthRenderbuffer?: WebGLRenderbuffer;
        width: number;
        height: number;
        format: TextureFormat;
        msaa: boolean;
        mipLevels: number;
    }
    
    interface TextureFormat {
        internalFormat: number;
        format: number;
        type: number;
        name: string;
    }
    
    private static readonly FORMATS = {
        RGBA8: { internalFormat: WebGL2RenderingContext.RGBA8, format: WebGL2RenderingContext.RGBA, type: WebGL2RenderingContext.UNSIGNED_BYTE, name: 'RGBA8' },
        RGBA16F: { internalFormat: WebGL2RenderingContext.RGBA16F, format: WebGL2RenderingContext.RGBA, type: WebGL2RenderingContext.HALF_FLOAT, name: 'RGBA16F' },
        RGBA32F: { internalFormat: WebGL2RenderingContext.RGBA32F, format: WebGL2RenderingContext.RGBA, type: WebGL2RenderingContext.FLOAT, name: 'RGBA32F' },
        DEPTH24_STENCIL8: { internalFormat: WebGL2RenderingContext.DEPTH24_STENCIL8, format: WebGL2RenderingContext.DEPTH_STENCIL, type: WebGL2RenderingContext.UNSIGNED_INT_24_8, name: 'DEPTH24_STENCIL8' }
    };
    
    public createFrameBuffer(
        name: string,
        width: number,
        height: number,
        config: {
            colorCount?: number;
            colorFormat?: keyof typeof FrameBufferManager.FORMATS;
            hasDepth?: boolean;
            depthFormat?: keyof typeof FrameBufferManager.FORMATS;
            msaa?: boolean;
            mipLevels?: number;
        } = {}
    ): FrameBufferObject {
        console.log(`🖼�?创建帧缓�? ${name} (${width}x${height})`);
        
        const fbo = this.gl.createFramebuffer()!;
        this.gl.bindFramebuffer(this.gl.FRAMEBUFFER, fbo);
        
        const colorCount = config.colorCount || 1;
        const colorFormat = FrameBufferManager.FORMATS[config.colorFormat || 'RGBA8'];
        const colorTextures: WebGLTexture[] = [];
        
        // 创建颜色纹理
        for (let i = 0; i < colorCount; i++) {
            const colorTexture = this.createTexture2D(width, height, colorFormat, config.mipLevels || 1);
            this.gl.framebufferTexture2D(
                this.gl.FRAMEBUFFER,
                this.gl.COLOR_ATTACHMENT0 + i,
                this.gl.TEXTURE_2D,
                colorTexture,
                0
            );
            colorTextures.push(colorTexture);
        }
        
        // 设置绘制缓冲�?        const drawBuffers = Array.from({length: colorCount}, (_, i) => this.gl.COLOR_ATTACHMENT0 + i);
        this.gl.drawBuffers(drawBuffers);
        
        // 创建深度缓冲�?        let depthTexture: WebGLTexture | undefined;
        let depthRenderbuffer: WebGLRenderbuffer | undefined;
        
        if (config.hasDepth) {
            if (config.depthFormat) {
                // 使用深度纹理
                const depthFormat = FrameBufferManager.FORMATS[config.depthFormat];
                depthTexture = this.createTexture2D(width, height, depthFormat, 1);
                this.gl.framebufferTexture2D(
                    this.gl.FRAMEBUFFER,
                    this.gl.DEPTH_STENCIL_ATTACHMENT,
                    this.gl.TEXTURE_2D,
                    depthTexture,
                    0
                );
            } else {
                // 使用深度渲染缓冲�?                depthRenderbuffer = this.gl.createRenderbuffer()!;
                this.gl.bindRenderbuffer(this.gl.RENDERBUFFER, depthRenderbuffer);
                this.gl.renderbufferStorage(this.gl.RENDERBUFFER, this.gl.DEPTH24_STENCIL8, width, height);
                this.gl.framebufferRenderbuffer(
                    this.gl.FRAMEBUFFER,
                    this.gl.DEPTH_STENCIL_ATTACHMENT,
                    this.gl.RENDERBUFFER,
                    depthRenderbuffer
                );
            }
        }
        
        // 检查完整�?        const status = this.gl.checkFramebufferStatus(this.gl.FRAMEBUFFER);
        if (status !== this.gl.FRAMEBUFFER_COMPLETE) {
            throw new Error(`帧缓冲不完整: ${this.getFramebufferStatusString(status)}`);
        }
        
        this.gl.bindFramebuffer(this.gl.FRAMEBUFFER, null);
        
        const frameBuffer: FrameBufferObject = {
            fbo: fbo,
            colorTextures: colorTextures,
            depthTexture: depthTexture,
            depthRenderbuffer: depthRenderbuffer,
            width: width,
            height: height,
            format: colorFormat,
            msaa: config.msaa || false,
            mipLevels: config.mipLevels || 1
        };
        
        this.frameBuffers.set(name, frameBuffer);
        
        console.log(`�?帧缓冲创建成�? ${colorCount}个颜色附�? 深度: ${config.hasDepth}`);
        return frameBuffer;
    }
    
    private createTexture2D(width: number, height: number, format: TextureFormat, mipLevels: number): WebGLTexture {
        const texture = this.gl.createTexture()!;
        this.gl.bindTexture(this.gl.TEXTURE_2D, texture);
        
        // 分配存储空间
        this.gl.texStorage2D(this.gl.TEXTURE_2D, mipLevels, format.internalFormat, width, height);
        
        // 设置过滤参数
        if (mipLevels > 1) {
            this.gl.texParameteri(this.gl.TEXTURE_2D, this.gl.TEXTURE_MIN_FILTER, this.gl.LINEAR_MIPMAP_LINEAR);
            this.gl.texParameteri(this.gl.TEXTURE_2D, this.gl.TEXTURE_MAG_FILTER, this.gl.LINEAR);
        } else {
            this.gl.texParameteri(this.gl.TEXTURE_2D, this.gl.TEXTURE_MIN_FILTER, this.gl.LINEAR);
            this.gl.texParameteri(this.gl.TEXTURE_2D, this.gl.TEXTURE_MAG_FILTER, this.gl.LINEAR);
        }
        
        this.gl.texParameteri(this.gl.TEXTURE_2D, this.gl.TEXTURE_WRAP_S, this.gl.CLAMP_TO_EDGE);
        this.gl.texParameteri(this.gl.TEXTURE_2D, this.gl.TEXTURE_WRAP_T, this.gl.CLAMP_TO_EDGE);
        
        return texture;
    }
    
    public bindFrameBuffer(name: string, clearColor?: [number, number, number, number]): boolean {
        const frameBuffer = this.frameBuffers.get(name);
        if (!frameBuffer) {
            console.error(`帧缓冲不存在: ${name}`);
            return false;
        }
        
        this.gl.bindFramebuffer(this.gl.FRAMEBUFFER, frameBuffer.fbo);
        this.gl.viewport(0, 0, frameBuffer.width, frameBuffer.height);
        
        if (clearColor) {
            this.gl.clearColor(clearColor[0], clearColor[1], clearColor[2], clearColor[3]);
            this.gl.clear(this.gl.COLOR_BUFFER_BIT | this.gl.DEPTH_BUFFER_BIT);
        }
        
        return true;
    }
}

🎨 后处理效果系�?

后处理管�?

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// 后处理基础着色器
CCProgram fullscreen-vs %{
  precision highp float;
  
  in vec2 a_position; // 全屏四边�?[-1,1]
  
  out vec2 v_uv;
  
  void vert() {
    v_uv = a_position * 0.5 + 0.5; // 转换到[0,1]
    gl_Position = vec4(a_position, 0.0, 1.0);
  }
}%

// 基础后处理片段着色器
CCProgram post-process-base-fs %{
  precision highp float;
  
  in vec2 v_uv;
  layout(location = 0) out vec4 fragColor;
  
  uniform sampler2D inputTexture;
  uniform vec4 screenSize; // xy: size, zw: inv_size
  
  // 基础采样函数
  vec4 sampleInput(vec2 uv) {
    return texture(inputTexture, uv);
  }
  
  vec4 sampleInputOffset(vec2 uv, vec2 offset) {
    return texture(inputTexture, uv + offset * screenSize.zw);
  }
  
  void frag() {
    fragColor = sampleInput(v_uv);
  }
}%

// 高斯模糊后处�?CCProgram gaussian-blur-fs %{
  precision highp float;
  
  in vec2 v_uv;
  layout(location = 0) out vec4 fragColor;
  
  uniform sampler2D inputTexture;
  uniform vec4 blurParams; // x: radius, y: direction(0=horizontal,1=vertical), z: strength, w: unused
  uniform vec4 screenSize;
  
  const float weights[5] = float[](0.227027, 0.1945946, 0.1216216, 0.0540541, 0.0162162);
  
  void frag() {
    vec2 texelSize = screenSize.zw;
    vec2 direction = blurParams.y < 0.5 ? vec2(1.0, 0.0) : vec2(0.0, 1.0);
    
    vec3 result = texture(inputTexture, v_uv).rgb * weights[0];
    
    for(int i = 1; i < 5; ++i) {
        vec2 offset = direction * float(i) * texelSize * blurParams.x;
        result += texture(inputTexture, v_uv + offset).rgb * weights[i];
        result += texture(inputTexture, v_uv - offset).rgb * weights[i];
    }
    
    fragColor = vec4(result, 1.0);
  }
}%

// Bloom后处�?CCProgram bloom-extract-fs %{
  precision highp float;
  
  in vec2 v_uv;
  layout(location = 0) out vec4 fragColor;
  
  uniform sampler2D inputTexture;
  uniform vec4 bloomParams; // x: threshold, y: knee, z: intensity, w: unused
  
  // 亮度提取
  float luminance(vec3 color) {
    return dot(color, vec3(0.2126, 0.7152, 0.0722));
  }
  
  vec3 thresholdFilter(vec3 color, float threshold, float knee) {
    float brightness = luminance(color);
    float softness = clamp(brightness - threshold + knee, 0.0, 2.0 * knee);
    softness = (softness * softness) / (4.0 * knee + 1e-4);
    float contribution = max(softness, brightness - threshold) / max(brightness, 1e-4);
    return color * contribution;
  }
  
  void frag() {
    vec3 color = texture(inputTexture, v_uv).rgb;
    vec3 bloom = thresholdFilter(color, bloomParams.x, bloomParams.y);
    fragColor = vec4(bloom * bloomParams.z, 1.0);
  }
}%

// Tone Mapping后处�?CCProgram tone-mapping-fs %{
  precision highp float;
  
  in vec2 v_uv;
  layout(location = 0) out vec4 fragColor;
  
  uniform sampler2D hdrTexture;
  uniform sampler2D bloomTexture;
  uniform vec4 toneMappingParams; // x: exposure, y: gamma, z: bloomStrength, w: type
  
  // ACES色调映射
  vec3 ACESFilm(vec3 x) {
    float a = 2.51;
    float b = 0.03;
    float c = 2.43;
    float d = 0.59;
    float e = 0.14;
    return clamp((x * (a * x + b)) / (x * (c * x + d) + e), 0.0, 1.0);
  }
  
  // Reinhard色调映射
  vec3 Reinhard(vec3 color) {
    return color / (1.0 + color);
  }
  
  void frag() {
    vec3 hdrColor = texture(hdrTexture, v_uv).rgb;
    vec3 bloomColor = texture(bloomTexture, v_uv).rgb;
    
    // 合并HDR和Bloom
    hdrColor += bloomColor * toneMappingParams.z;
    
    // 应用曝光
    hdrColor *= toneMappingParams.x;
    
    // 色调映射
    vec3 mapped;
    if (toneMappingParams.w < 0.5) {
        mapped = Reinhard(hdrColor);
    } else {
        mapped = ACESFilm(hdrColor);
    }
    
    // 伽马校正
    mapped = pow(mapped, vec3(1.0 / toneMappingParams.y));
    
    fragColor = vec4(mapped, 1.0);
  }
}%

TypeScript后处理系�?

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// 后处理效果管理器
class PostProcessingManager {
    private gl: WebGL2RenderingContext;
    private fboManager: FrameBufferManager;
    private effects: Map<string, PostEffect> = new Map();
    private effectChain: string[] = [];
    private tempBuffers: string[] = ['temp0', 'temp1'];
    
    interface PostEffect {
        name: string;
        shader: Shader;
        enabled: boolean;
        parameters: Map<string, any>;
        renderFunc?: (input: string, output: string) => void;
    }
    
    constructor(gl: WebGL2RenderingContext, fboManager: FrameBufferManager) {
        this.gl = gl;
        this.fboManager = fboManager;
        this.initializeTempBuffers();
    }
    
    private initializeTempBuffers(): void {
        const width = this.gl.canvas.width;
        const height = this.gl.canvas.height;
        
        // 创建临时缓冲�?        this.fboManager.createFrameBuffer('temp0', width, height, {
            colorFormat: 'RGBA16F',
            hasDepth: false
        });
        
        this.fboManager.createFrameBuffer('temp1', width, height, {
            colorFormat: 'RGBA16F',
            hasDepth: false
        });
        
        // Bloom用的低分辨率缓冲�?        this.fboManager.createFrameBuffer('bloom_extract', width / 2, height / 2, {
            colorFormat: 'RGBA16F',
            hasDepth: false
        });
        
        this.fboManager.createFrameBuffer('bloom_blur_h', width / 4, height / 4, {
            colorFormat: 'RGBA16F',
            hasDepth: false
        });
        
        this.fboManager.createFrameBuffer('bloom_blur_v', width / 4, height / 4, {
            colorFormat: 'RGBA16F',
            hasDepth: false
        });
    }
    
    public addEffect(name: string, shader: Shader, parameters: {[key: string]: any} = {}): void {
        const effect: PostEffect = {
            name: name,
            shader: shader,
            enabled: true,
            parameters: new Map(Object.entries(parameters))
        };
        
        this.effects.set(name, effect);
        
        console.log(`�?添加后处理效�? ${name}`);
    }
    
    public setEffectChain(chain: string[]): void {
        this.effectChain = chain.filter(name => this.effects.has(name));
        console.log(`🔗 设置后处理链: ${this.effectChain.join(' -> ')}`);
    }
    
    public setEffectParameter(effectName: string, paramName: string, value: any): void {
        const effect = this.effects.get(effectName);
        if (effect) {
            effect.parameters.set(paramName, value);
        }
    }
    
    public processFrame(inputTexture: WebGLTexture): void {
        if (this.effectChain.length === 0) {
            this.copyToScreen(inputTexture);
            return;
        }
        
        let currentInput = 'input';
        let currentOutput = 'temp0';
        let tempIndex = 0;
        
        // 将输入纹理绑定到temp缓冲区用于读�?        // 这里简化处理，实际需要更复杂的纹理管�?        
        for (let i = 0; i < this.effectChain.length; i++) {
            const effectName = this.effectChain[i];
            const effect = this.effects.get(effectName);
            
            if (!effect || !effect.enabled) continue;
            
            // 确定输出目标
            if (i === this.effectChain.length - 1) {
                currentOutput = 'screen'; // 最后一个效果输出到屏幕
            } else {
                currentOutput = this.tempBuffers[tempIndex % 2];
            }
            
            // 执行效果
            this.executeEffect(effect, currentInput, currentOutput);
            
            // 为下一个效果准备输�?            currentInput = this.tempBuffers[tempIndex % 2];
            tempIndex++;
        }
    }
    
    private executeEffect(effect: PostEffect, inputBuffer: string, outputBuffer: string): void {
        console.log(`🎨 执行后处�? ${effect.name} (${inputBuffer} -> ${outputBuffer})`);
        
        // 特殊效果的自定义渲染逻辑
        if (effect.renderFunc) {
            effect.renderFunc(inputBuffer, outputBuffer);
            return;
        }
        
        // 绑定输出缓冲�?        if (outputBuffer === 'screen') {
            this.gl.bindFramebuffer(this.gl.FRAMEBUFFER, null);
            this.gl.viewport(0, 0, this.gl.canvas.width, this.gl.canvas.height);
        } else {
            this.fboManager.bindFrameBuffer(outputBuffer);
        }
        
        // 使用着色器
        this.gl.useProgram(effect.shader.program);
        
        // 设置参数
        this.setEffectUniforms(effect);
        
        // 绑定输入纹理
        // 这里需要从inputBuffer获取纹理并绑�?        
        // 渲染全屏四边�?        this.renderFullscreenQuad();
    }
    
    public setupBloomEffect(): void {
        // Bloom效果的自定义渲染逻辑
        const bloomEffect: PostEffect = {
            name: 'bloom',
            shader: this.getBloomShader(),
            enabled: true,
            parameters: new Map([
                ['threshold', 1.0],
                ['knee', 0.5],
                ['intensity', 1.0],
                ['radius', 2.0]
            ]),
            renderFunc: (input: string, output: string) => {
                this.renderBloom(input, output);
            }
        };
        
        this.effects.set('bloom', bloomEffect);
    }
    
    private renderBloom(input: string, output: string): void {
        console.log(`🌟 渲染Bloom效果`);
        
        // 1. 亮度提取
        this.fboManager.bindFrameBuffer('bloom_extract');
        this.gl.useProgram(this.getBloomExtractShader().program);
        // 设置阈值参�?        this.renderFullscreenQuad();
        
        // 2. 下采样和水平模糊
        this.fboManager.bindFrameBuffer('bloom_blur_h');
        this.gl.useProgram(this.getGaussianBlurShader().program);
        // 设置水平模糊参数
        this.renderFullscreenQuad();
        
        // 3. 垂直模糊
        this.fboManager.bindFrameBuffer('bloom_blur_v');
        // 设置垂直模糊参数
        this.renderFullscreenQuad();
        
        // 4. 合成到输�?        if (output === 'screen') {
            this.gl.bindFramebuffer(this.gl.FRAMEBUFFER, null);
        } else {
            this.fboManager.bindFrameBuffer(output);
        }
        
        this.gl.useProgram(this.getBloomCompositeShader().program);
        // 绑定原始纹理和模糊纹�?        this.renderFullscreenQuad();
    }
    
    private renderFullscreenQuad(): void {
        // 渲染全屏四边形的顶点数据
        const vertices = new Float32Array([
            -1, -1,
             1, -1,
            -1,  1,
             1,  1
        ]);
        
        const vbo = this.gl.createBuffer();
        this.gl.bindBuffer(this.gl.ARRAY_BUFFER, vbo);
        this.gl.bufferData(this.gl.ARRAY_BUFFER, vertices, this.gl.STATIC_DRAW);
        
        const posLocation = this.gl.getAttribLocation(this.gl.getParameter(this.gl.CURRENT_PROGRAM), 'a_position');
        this.gl.enableVertexAttribArray(posLocation);
        this.gl.vertexAttribPointer(posLocation, 2, this.gl.FLOAT, false, 0, 0);
        
        this.gl.drawArrays(this.gl.TRIANGLE_STRIP, 0, 4);
        
        this.gl.deleteBuffer(vbo);
    }
}

🖼�?高级渲染纹理应用

屏幕空间反射(SSR)

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// 屏幕空间反射着色器
CCProgram ssr-fs %{
  precision highp float;
  
  in vec2 v_uv;
  layout(location = 0) out vec4 fragColor;
  
  uniform sampler2D colorTexture;
  uniform sampler2D normalTexture;
  uniform sampler2D depthTexture;
  uniform sampler2D roughnessTexture;
  
  uniform mat4 viewMatrix;
  uniform mat4 projMatrix;
  uniform mat4 invViewMatrix;
  uniform mat4 invProjMatrix;
  uniform vec4 ssrParams; // x: maxDistance, y: resolution, z: thickness, w: fadeDistance
  
  // 从深度重构视图空间位�?  vec3 reconstructViewPos(vec2 uv, float depth) {
    vec4 clipPos = vec4(uv * 2.0 - 1.0, depth * 2.0 - 1.0, 1.0);
    vec4 viewPos = invProjMatrix * clipPos;
    return viewPos.xyz / viewPos.w;
  }
  
  // 光线步进
  vec2 rayMarch(vec3 rayStart, vec3 rayDir, float maxDistance) {
    float stepSize = maxDistance / ssrParams.y; // resolution控制步数
    vec3 currentPos = rayStart;
    
    for (float i = 0.0; i < ssrParams.y; i += 1.0) {
      currentPos += rayDir * stepSize;
      
      // 转换到屏幕空�?      vec4 clipPos = projMatrix * vec4(currentPos, 1.0);
      vec3 screenPos = clipPos.xyz / clipPos.w;
      vec2 screenUV = screenPos.xy * 0.5 + 0.5;
      
      // 检查边�?      if (screenUV.x < 0.0 || screenUV.x > 1.0 || screenUV.y < 0.0 || screenUV.y > 1.0) {
        break;
      }
      
      // 采样深度
      float sceneDepth = texture(depthTexture, screenUV).r;
      vec3 sceneViewPos = reconstructViewPos(screenUV, sceneDepth);
      
      // 检查相�?      float depthDiff = abs(currentPos.z - sceneViewPos.z);
      if (depthDiff < ssrParams.z && currentPos.z > sceneViewPos.z) {
        return screenUV;
      }
    }
    
    return vec2(-1.0); // 未找到相�?  }
  
  void frag() {
    vec4 normalData = texture(normalTexture, v_uv);
    vec3 normal = normalData.rgb * 2.0 - 1.0;
    float roughness = texture(roughnessTexture, v_uv).r;
    
    // 粗糙表面不计算反�?    if (roughness > 0.8) {
      fragColor = vec4(0.0);
      return;
    }
    
    float depth = texture(depthTexture, v_uv).r;
    vec3 viewPos = reconstructViewPos(v_uv, depth);
    vec3 viewDir = normalize(-viewPos);
    vec3 reflectDir = reflect(-viewDir, normal);
    
    // 光线步进
    vec2 hitUV = rayMarch(viewPos, reflectDir, ssrParams.x);
    
    if (hitUV.x >= 0.0) {
      vec3 reflectionColor = texture(colorTexture, hitUV).rgb;
      
      // 根据距离衰减
      float fadeDistance = length(hitUV - v_uv) / ssrParams.w;
      float fade = 1.0 - clamp(fadeDistance, 0.0, 1.0);
      
      // 根据粗糙度调整反射强�?      float reflectance = 1.0 - roughness;
      
      fragColor = vec4(reflectionColor, fade * reflectance);
    } else {
      fragColor = vec4(0.0);
    }
  }
}%

实时阴影映射

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// 实时阴影映射系统
class RealtimeShadowSystem {
    private cascadedShadowMaps: WebGLTexture[] = [];
    private shadowMapSize: number = 2048;
    private cascadeCount: number = 4;
    
    interface ShadowCascade {
        viewMatrix: mat4;
        projMatrix: mat4;
        splitDistance: number;
        shadowBounds: BoundingBox;
    }
    
    public setupCascadedShadowMaps(): void {
        console.log(`🌑 设置级联阴影映射 (${this.cascadeCount}�?`);
        
        // 创建2D数组纹理用于级联阴影
        const shadowMapArray = this.gl.createTexture()!;
        this.gl.bindTexture(this.gl.TEXTURE_2D_ARRAY, shadowMapArray);
        
        this.gl.texImage3D(
            this.gl.TEXTURE_2D_ARRAY,
            0,
            this.gl.DEPTH_COMPONENT24,
            this.shadowMapSize,
            this.shadowMapSize,
            this.cascadeCount,
            0,
            this.gl.DEPTH_COMPONENT,
            this.gl.UNSIGNED_INT,
            null
        );
        
        this.gl.texParameteri(this.gl.TEXTURE_2D_ARRAY, this.gl.TEXTURE_MIN_FILTER, this.gl.LINEAR);
        this.gl.texParameteri(this.gl.TEXTURE_2D_ARRAY, this.gl.TEXTURE_MAG_FILTER, this.gl.LINEAR);
        this.gl.texParameteri(this.gl.TEXTURE_2D_ARRAY, this.gl.TEXTURE_WRAP_S, this.gl.CLAMP_TO_BORDER);
        this.gl.texParameteri(this.gl.TEXTURE_2D_ARRAY, this.gl.TEXTURE_WRAP_T, this.gl.CLAMP_TO_BORDER);
        
        // 设置边界颜色为白�?无阴�?
        this.gl.texParameterfv(this.gl.TEXTURE_2D_ARRAY, this.gl.TEXTURE_BORDER_COLOR, [1.0, 1.0, 1.0, 1.0]);
        
        this.cascadedShadowMaps.push(shadowMapArray);
    }
    
    public calculateCascadeSplits(camera: Camera, lightDir: vec3): ShadowCascade[] {
        const cascades: ShadowCascade[] = [];
        const nearPlane = camera.near;
        const farPlane = camera.far;
        
        // 计算级联分割距离
        const splitDistances: number[] = [];
        for (let i = 0; i < this.cascadeCount; i++) {
            const ratio = (i + 1) / this.cascadeCount;
            const logarithmic = nearPlane * Math.pow(farPlane / nearPlane, ratio);
            const uniform = nearPlane + (farPlane - nearPlane) * ratio;
            const splitDistance = mix(uniform, logarithmic, 0.5); // 混合分割
            splitDistances.push(splitDistance);
        }
        
        let prevSplitDistance = nearPlane;
        
        for (let i = 0; i < this.cascadeCount; i++) {
            const cascade = this.calculateCascadeMatrices(
                camera,
                lightDir,
                prevSplitDistance,
                splitDistances[i]
            );
            cascades.push(cascade);
            prevSplitDistance = splitDistances[i];
        }
        
        return cascades;
    }
    
    private calculateCascadeMatrices(
        camera: Camera,
        lightDir: vec3,
        nearDist: number,
        farDist: number
    ): ShadowCascade {
        // 计算级联的视锥体角点
        const frustumCorners = this.calculateFrustumCorners(camera, nearDist, farDist);
        
        // 计算包围�?        const center = this.calculateCenter(frustumCorners);
        const radius = this.calculateRadius(frustumCorners, center);
        
        // 光源视图矩阵
        const lightPos = vec3.subtract(vec3.create(), center, vec3.scale(vec3.create(), lightDir, radius * 2));
        const lightView = mat4.lookAt(mat4.create(), lightPos, center, [0, 1, 0]);
        
        // 正交投影矩阵
        const lightProj = mat4.ortho(mat4.create(), -radius, radius, -radius, radius, 0.1, radius * 4);
        
        return {
            viewMatrix: lightView,
            projMatrix: lightProj,
            splitDistance: farDist,
            shadowBounds: this.calculateShadowBounds(frustumCorners, lightView, lightProj)
        };
    }
    
    public renderShadowCascades(cascades: ShadowCascade[], renderList: RenderObject[]): void {
        console.log(`🌑 渲染级联阴影映射`);
        
        const shadowFBO = this.fboManager.getFrameBuffer('cascaded_shadows');
        
        for (let i = 0; i < cascades.length; i++) {
            // 绑定到特定层
            this.gl.bindFramebuffer(this.gl.FRAMEBUFFER, shadowFBO.fbo);
            this.gl.framebufferTextureLayer(
                this.gl.FRAMEBUFFER,
                this.gl.DEPTH_ATTACHMENT,
                this.cascadedShadowMaps[0],
                0,
                i
            );
            
            this.gl.viewport(0, 0, this.shadowMapSize, this.shadowMapSize);
            this.gl.clear(this.gl.DEPTH_BUFFER_BIT);
            
            // 设置光源矩阵
            const lightViewProj = mat4.multiply(mat4.create(), cascades[i].projMatrix, cascades[i].viewMatrix);
            
            // 渲染阴影投射�?            renderList.forEach(obj => {
                if (obj.castShadow && this.objectInCascade(obj, cascades[i])) {
                    this.renderObjectToShadowMap(obj, lightViewProj);
                }
            });
        }
    }
}

📝 本章小结

通过本教程，你应该掌握了�?

  1. 渲染纹理基础: 理解FBO和渲染纹理的工作原理
  2. *后处理系�?: 学会实现完整的后处理效果管线
  3. 高级应用: 掌握SSR、阴影映射等高级技�?4. 性能优化: 了解渲染纹理的内存管理和优化策略

�?3章：高级渲染技术完结！🎮�?

🚀 下一步学�?

继续学习跨平台兼容性技术！🌐