GLSL RGB -> HSL

gistfile1.txt

vec3 rgb2hsl( vec3 _input ){
  float h = 0.0;
	float s = 0.0;
	float l = 0.0;
	float r = _input.r;
	float g = _input.g;
	float b = _input.b;
	float cMin = min( r, min( g, b ) );
	float cMax = max( r, max( g, b ) );

	l = ( cMax + cMin ) / 2.0;
	if ( cMax > cMin ) {
		float cDelta = cMax - cMin;
        
		s = l < .05 ? cDelta / ( cMax + cMin ) : cDelta / ( 2.0 - ( cMax + cMin ) );

		// hue
		if ( r == cMax ) {
			h = ( g - b ) / cDelta;
		} else if ( g == cMax ) {
			h = 2.0 + ( b - r ) / cDelta;
		} else {
			h = 4.0 + ( r - g ) / cDelta;
		}

		if ( h < 0.0) {
			h += 6.0;
		}
		h = h / 6.0;
	}
	return vec3( h, s, l );
}