//glsl计算sprite的亮度饱和度对比度

#ifdef GL_ES

precision mediump float;

#endif

uniform sampler2D u_texture;

varying vec2 v_texCoord;

varying vec4 v_fragmentColor;               

void main(void)

{

    vec4 color = texture2D(u_texture, v_texCoord);

    if(color.a >= 0.4)

    {

        vec3 avg = vec3(0.5,0.5,0.5);

        vec3 luncoeff = vec3 (0.2125, 0.7154, 0.0721);

        float T1 = 0.4;

        float T2 = 2.4;

        //计算亮度

        vec3 brtColor = color.rgb * T2;

        float intensityf = dot(brtColor,luncoeff);

        vec3 intensity = vec3(intensityf,intensityf,intensityf);

        //计算饱和度

        vec3 satColor = vec3(mix(intensity, brtColor, .));

        //计算对比度

        vec3 conColor = vec3(mix(avg, satColor, T1));

        gl_FragColor = vec4(conColor.r,conColor.g,conColor.b,color.a);

    }

    else

    {

        gl_FragColor = color;

    }

}