'#version 300 es\nprecision mediump float;\n\nuniform sampler2D colorSampler;\nuniform int bufferChannel; // 0=Y, 1=U, 2=V\nin vec2 texCoords;\nout float outColor;\n\nvec4 unmultAlpha(vec4 color) {\n    if (color.a == 0.) return vec4(0.);\n    return vec4(color.rgb / color.a, color.a);\n}\n\nvoid main() {\n    vec2 flippedCoords = vec2(texCoords.x, 1. - texCoords.y);\n    vec4 color = unmultAlpha(texture(colorSampler, flippedCoords));\n\n    // See http://avisynth.nl/index.php/Color_conversions\n    // BT.601 = vec3(0.299, 0.587, 0.114)\n    // BT.709 = vec3(0.2126, 0.7152, 0.0722)\n    vec3 coef = vec3(0.2126, 0.7152, 0.0722);\n\n    float y = dot(color.rgb, coef);\n    float u = (color.b - y) / (1. - coef.b);\n    float v = (color.r - y) / (1. - coef.r);\n\n    if (bufferChannel == 0) {\n        outColor = mix(16./255., 236./255., y);\n    } else if (bufferChannel == 1) {\n        outColor = mix(16./255., 240./255., u * 0.5 + 0.5);\n    } else if (bufferChannel == 2) {\n        outColor = mix(16./255., 240./255., v * 0.5 + 0.5);\n    }\n}\n