tanqiu/assets/resources/shaders/scan-effects.effect

// Copyright (c) 2017-2020 Xiamen Yaji Software Co., Ltd.
CCEffect %{
  techniques:
  - passes:
    - vert: sprite-vs:vert
      frag: sprite-fs:frag
      depthStencilState:
        depthTest: false
        depthWrite: false
      blendState:
        targets:
        - blend: true
          blendSrc: src_alpha
          blendDst: one_minus_src_alpha
          blendDstAlpha: one_minus_src_alpha
      rasterizerState:
        cullMode: none
      properties:
        scanColor: { value: [0.5, 0.5, 0.5, 0.2] }
        scanWidth: { value: 0.05 }
        scanSpeed: { value: 1.0 }
        scanIntensity: { value: 2.0 }
        alphaThreshold: { value: 0.5 }
}%

CCProgram sprite-vs %{
  precision highp float;
  #include <builtin/uniforms/cc-global>
  #if USE_LOCAL
    #include <builtin/uniforms/cc-local>
  #endif
  #if SAMPLE_FROM_RT
    #include <common/common-define>
  #endif
  in vec3 a_position;
  in vec2 a_texCoord;
  in vec4 a_color;

  out vec4 color;
  out vec2 uv0;

  vec4 vert () {
    vec4 pos = vec4(a_position, 1);

    #if USE_LOCAL
      pos = cc_matWorld * pos;
    #endif

    #if USE_PIXEL_ALIGNMENT
      pos = cc_matView * pos;
      pos.xyz = floor(pos.xyz);
      pos = cc_matProj * pos;
    #else
      pos = cc_matViewProj * pos;
    #endif

    uv0 = a_texCoord;
    #if SAMPLE_FROM_RT
      CC_HANDLE_RT_SAMPLE_FLIP(uv0);
    #endif
    color = a_color;

    return pos;
  }
}%

CCProgram sprite-fs %{
  precision highp float;
  #include <builtin/internal/embedded-alpha>
  #include <builtin/internal/alpha-test>
  #include <builtin/uniforms/cc-global>
  
  in vec4 color;

  #if USE_TEXTURE
    in vec2 uv0;
    #pragma builtin(local)
    layout(set = 2, binding = 12) uniform sampler2D cc_spriteTexture;
  #endif

  uniform ScanUniforms {
    vec4 scanColor;
    float scanWidth;
    float scanSpeed;
    float scanIntensity;
  };

  vec4 frag () {
    vec4 o = vec4(1, 1, 1, 1);

    #if USE_TEXTURE
      o *= CCSampleWithAlphaSeparated(cc_spriteTexture, uv0);
      
      // 计算扫描线位置 (从右下到左上)
      float scanPosition = mod(cc_time.x * scanSpeed, 2.0 + scanWidth);
      
      // 计算当前像素到扫描线的距离 (对角线扫描)
      float diagonalPos = (1.0-(uv0.x + uv0.y) * 0.5); // 从右下到左上的对角线位置
      float distanceToScan = abs(diagonalPos - scanPosition);
      
      // 创建扫描线效果
      float scanEffect = 0.0;
      if (distanceToScan < scanWidth) {
        // 在扫描线范围内，计算强度
        float normalizedDistance = distanceToScan / scanWidth;
        scanEffect = (1.0 - normalizedDistance) * scanIntensity;
        
        // 使用平滑过渡
        scanEffect = smoothstep(0.0, 1.0, scanEffect);
      }
      
      // 应用扫描效果
      if (scanEffect > 0.0) {
        // 混合原始颜色和扫描颜色
        o.rgb = mix(o.rgb, scanColor.rgb, scanEffect * scanColor.a);
        // 增加亮度
        o.rgb += scanColor.rgb * scanEffect * 0.5;
      }
      
    #endif

    o *= color;
    ALPHA_TEST(o);
    return o;
  }
}%