/*
     File: Shader.fsh
 Abstract: Fragment shader for converting Y/UV textures to RGB.
  Version: 1.0
 
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 */

uniform sampler2D SamplerY;
uniform sampler2D SamplerU;
uniform sampler2D SamplerV;

varying highp vec2 texCoordVarying;

void main()
{
    mediump vec3 yuv;
    lowp vec3 rgb;
    
    yuv.x = texture2D(SamplerY, texCoordVarying).r;
    yuv.y = texture2D(SamplerU, texCoordVarying).r - 0.5;
    yuv.z = texture2D(SamplerV, texCoordVarying).r - 0.5;
    
    // BT.601, which is the standard for SDTV is provided as a reference
    
    /*rgb = mat3(    1,       1,     1,
                   0, -.34413, 1.772,
               1.402, -.71414,     0) * yuv;*/
     
    
    // Using BT.709 which is the standard for HDTV
    rgb = mat3(      1,       1,      1,
                     0, -.18732, 1.8556,
               1.57481, -.46813,      0) * yuv;
    
    gl_FragColor = vec4(rgb, 1);
}