/*{
    "CATEGORIES": [
        "Color Adjustment",
        "Film",
        "v002"
    ],
    "CREDIT": "by v002",
    "INPUTS": [
        {
            "NAME": "inputImage",
            "TYPE": "image"
        },
        {
            "DEFAULT": 0,
            "MAX": 1,
            "MIN": 0,
            "NAME": "amount",
            "TYPE": "float"
        }
    ],
    "ISFVSN": "2"
}
*/

//	Based on v002 bleach bypass – https://github.com/v002/v002-Film-Effects/

//constant variables.
const vec4 one = vec4(1.0);	
const vec4 two = vec4(2.0);
//const vec4 lumcoeff = vec4(0.2125,0.7154,0.0721,0.0);
const vec4 lumcoeff = vec4(0.2126, 0.7152, 0.0722, 0.0);


vec4 overlay(vec4 myInput, vec4 previousmix, vec4 amount)
{
	float luminance = dot(previousmix,lumcoeff);
	float mixamount = clamp((luminance - 0.45) * 10., 0., 1.);

	vec4 branch1 = two * previousmix * myInput;
	vec4 branch2 = one - (two * (one - previousmix) * (one - myInput));

	vec4 result = mix(branch1, branch2, vec4(mixamount) );

	return mix(previousmix, result, amount);
}

void main (void) 
{ 		
	vec4 input0 = IMG_THIS_PIXEL(inputImage);

	vec4 luma = vec4(dot(input0,lumcoeff));

	gl_FragColor = overlay(luma, input0, vec4(amount));

}