LYGIA Shader Library

Use:

blendOverlay(<float|vec3> base, <float|vec3> blend [, <float> opacity])

Check it on Github

#ifndef FNC_BLENDOVERLAY
#define FNC_BLENDOVERLAY
float blendOverlay(in float base, in float blend) {
    return (base < .5)? (2.*base*blend): (1. - 2. * (1. - base) * (1. - blend));
}

vec3 blendOverlay(in vec3 base, in vec3 blend) {
    return vec3(blendOverlay(base.r, blend.r),
                blendOverlay(base.g, blend.g),
                blendOverlay(base.b, blend.b));
}

vec3 blendOverlay(in vec3 base, in vec3 blend, in float opacity) {
    return (blendOverlay(base, blend) * opacity + base * (1. - opacity));
}
#endif

Use:

blendOverlay(<float|float3> base, <float|float3> blend [, <float> opacity])

Check it on Github

#ifndef FNC_BLENDOVERLAY
#define FNC_BLENDOVERLAY
float blendOverlay(in float base, in float blend) {
    return (base < .5)? (2.*base*blend): (1. - 2. * (1. - base) * (1. - blend));
}

float3 blendOverlay(in float3 base, in float3 blend) {
    return float3(  blendOverlay(base.r, blend.r),
                    blendOverlay(base.g, blend.g),
                    blendOverlay(base.b, blend.b) );
}

float3 blendOverlay(in float3 base, in float3 blend, in float opacity) {
    return (blendOverlay(base, blend) * opacity + base * (1. - opacity));
}
#endif