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++ vec4 desaturate(vec3 color, float strength)
++ {
++ vec3 lum = vec3(0.299, 0.587, 0.114); // lum values based on: ITU-R BT.601
++ vec3 gray = vec3(dot(lum, color));
++ return vec4(mix(color, gray, -strength), 1.0);
++ }
++
++ void MAIN()
++ {
++ vec4 sourceColor = texture(INPUT, INPUT_UV);
++ vec4 basecolor = vec4(sourceColor.r * redStrength, sourceColor.g * greenStrength, sourceColor.b * blueStrength, sourceColor.a);
++ FRAGCOLOR = desaturate(basecolor.rgb, saturation);
++ }