uniform sampler2D colorSampler;

uniform float Saturation;

varying vec2 uv;

void main() {

    vec4 color = texture2D(colorSampler, uv);

    vec4 scaledColor = color * vec4(0.3, 0.59, 0.11, 1.0);

    float luminance = scaledColor.r + scaledColor.g + scaledColor.b ;

    vec4 lerped = mix(vec4(luminance,luminance,luminance,color.a), color, Saturation);

    gl_FragColor = lerped;

}