#version 330
uniform sampler2D texA;

in vec2 ftexcoord;
layout(location = 0) out vec4 rgbColour;
//layout(location = 0) out vec4 yuvColour;


void main()
{
    float y;
    float cb;
    float cr;

    vec2 txc = gl_FragCoord.xy;
    ivec2 texSize  = textureSize(texA, 0);
    vec2 texOffset = 1 / vec2(texSize.xy);

    y = texture(texA, ftexcoord).r;

    if (mod(txc.x, 2) > 1)
    {
        cb = texture(texA, ftexcoord.xy + texOffset * vec2(1.0, 0.0)).g - 0.5;
        cr = texture(texA, ftexcoord).g - 0.5;
    }
    else
    {
        cb = texture(texA, ftexcoord).g - 0.5;
        cr = texture(texA, ftexcoord.xy + texOffset * vec2(-1.0, 0.0)).g - 0.5;
    }

    rgbColour.r =  y + 1.5958* cr;
    rgbColour.g = y - 0.39173 * cb - 0.81290 * cr;
    rgbColour.b =  y + 2.017*cb;

}