precision mediump float;
uniform sampler2D u_Texture0;
uniform sampler2D u_Texture1;
varying vec2 v_TexCoordinate;
const vec3 W = vec3(0.2125, 0.7154, 0.0721);

//JASNOŚĆ, KONTRAST, SATURACJA
vec3 BrightnessContrastSaturation(vec3 color, float brt, float con, float sat)
{
    vec3 black = vec3(0., 0., 0.);
    vec3 middle = vec3(0.5, 0.5, 0.5);
    float luminance = dot(color, W);
    vec3 gray = vec3(luminance, luminance, luminance);

    vec3 brtColor = mix(black, color, brt);
    vec3 conColor = mix(middle, brtColor, con);
    vec3 satColor = mix(gray, conColor, sat);
    return satColor;
}

//DODAJE INNY OBRAZ W TRYBIE OVERLAY
vec3 ovelayBlender(vec3 Color, vec3 filter){
    vec3 filter_result;

    float luminance = dot(filter, W);

    if(luminance < 0.5)
        filter_result = 2. * filter * Color;
    else
        filter_result = 1. - (1. - (2. *(filter - 0.5)))*(1. - Color);

    return filter_result;
}

void main()
{
     vec2 st = v_TexCoordinate.st;
     vec3 irgb = texture2D(u_Texture0, st).rgb;
     vec3 filter = texture2D(u_Texture1, st).rgb;

     float T_bright = 1.2;
     float T_contrast = 1.0;
     float T_saturation = 0.9;
     vec3 bcs_result = BrightnessContrastSaturation(irgb, T_bright, T_contrast, T_saturation);

     //WIĘCEJ CZERWONEGO, MNIEJ NIEBIESKIEGO
     vec3 rb_result = vec3(bcs_result.r*1.1, bcs_result.g, bcs_result.b*0.9);

     vec3 after_filter = mix(rb_result, ovelayBlender(rb_result, filter), 0.5);

     gl_FragColor = vec4(after_filter, 1.);
}