//!HOOK MAIN
//!BIND HOOKED
//!DESC Vibrance.35

#define Vibrance 0.35

/* --- vibrance (mpv glsl.hook) --- */
/* v1.40 (2023-07) released by butterw under GPLv3
(1 texture, 9 arithmetic).

Smart saturation (or desaturation). Protects skin tones from excessive adjustments.

- Vibrance parameter, [-1, 1.0], 0: no effect
>> Positive: saturates low-saturation pixels first, ex: 0.35
negative: reduces saturation of high-saturation pixels first, ex: -0.15

Simplified version of SweetFx.Vibrance.
Calculates a saturation measure, then applies saturation based on it.
Affects color only, no effect on grays.
*/

#define CoefLuma vec4(0.2126, 0.7152, 0.0722, 0) //sRGB, HDTV

vec4 hook() {
	vec4 c0 = HOOKED_texOff(0);
	float colorSat = max(max(c0.r, c0.g), c0.b) - min(min(c0.r, c0.g), c0.b); // >=0, 5 arithmetic

	colorSat = 1.0+Vibrance -abs(Vibrance)*colorSat;
	c0.rgb = mix(vec3(dot(c0, CoefLuma)), c0.rgb, colorSat);
	return c0;
}