//高斯模糊效果(在华为P6上不生效)

CCEffect %{
  techniques:
  - passes:
    - vert: vs
      frag: fs
      blendState:
        targets:
        - blend: true
      rasterizerState:
        cullMode: none
      properties:
        texture: { value: white }
        u_degree: { value: 0.03 }
        u_brightness: { value: 1.0 }
}%

CCProgram vs %{ // 顶点Shader模块开始
  #include <cc-global>
  precision highp float;	  //定义float高精度
	in vec3 a_position; // 顶点Shader 从渲染管道里面获取的顶点信息,使用attribute来修饰;
	in vec2 a_uv0;   // 纹理坐标;
	out vec2 uv0;     // 传递给着色Shader，varying 来修饰，进行插值
	void main () {
		gl_Position = cc_matViewProj * vec4(a_position, 1);
		uv0 = a_uv0;
	}
}%

CCProgram fs %{
  #define repeats 5.  //重复次数，值越大模糊质量越高，但性能越低
  precision highp float;
  in vec2 uv0;
  uniform sampler2D texture;
  uniform ARGS{
    float u_degree;     //模糊度，外界属性
    float u_brightness; //亮度，外界属性
  };

  // 应用贴图UV
  vec4 draw(vec2 uv) {
      return  texture2D(texture,uv).rgba; 
  }

  float grid(float var, float size) {
      return floor(var*size)/size;
  }

  // 降低亮度
  vec4 dim(vec4 col, float factor) {
    return vec4(col.r * factor, col.g * factor, col.b * factor, col.a);
  }
    
  // 随机值
  float rand(vec2 co){
      return fract(sin(dot(co.xy ,vec2(12.9898,78.233))) * 43758.5453);
  }

  void main()
  {
    // 模糊贴图
    vec4 blurred_image = vec4(0.);
    // 重复采样
    for (float i = 0.; i < repeats; i++) { 
      // 第一采样点
      vec2 q = vec2(cos(degrees((i/repeats)*360.)),sin(degrees((i/repeats)*360.))) * (rand(vec2(i,uv0.x+uv0.y))+u_degree); 
      vec2 uv2 = uv0+(q*u_degree);
      blurred_image += draw(uv2)/2.;
      // 第二采样点
      q = vec2(cos(degrees((i/repeats)*360.)),sin(degrees((i/repeats)*360.))) * (rand(vec2(i+2.,uv0.x+uv0.y+24.))+u_degree); 
      uv2 = uv0+(q*u_degree);
      blurred_image += draw(uv2)/2.;
    }
    // 中和
    blurred_image /= repeats;
    // 降低亮度
    blurred_image = dim(blurred_image, u_brightness);
    // 导出颜色
    gl_FragColor = vec4(blurred_image);
  }
}%