/*****************************************************************************************
 *                                                                                       *
 * OpenSpace                                                                             *
 *                                                                                       *
 * Copyright (c) 2014                                                                    *
 *                                                                                       *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this  *
 * software and associated documentation files (the "Software"), to deal in the Software *
 * without restriction, including without limitation the rights to use, copy, modify,    *
 * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to    *
 * permit persons to whom the Software is furnished to do so, subject to the following   *
 * conditions:                                                                           *
 *                                                                                       *
 * The above copyright notice and this permission notice shall be included in all copies *
 * or substantial portions of the Software.                                              *
 *                                                                                       *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,   *
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A         *
 * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT    *
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF  *
 * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE  *
 * OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                                         *
 ****************************************************************************************/

#ifndef BLENDING_HGLSL
#define BLENDING_HGLSL

vec4 blendOver(vec4 oldColor, vec4 newColor)
{
	vec4 toReturn;
	toReturn.rgb =
		(newColor.rgb * newColor.a + oldColor.rgb * oldColor.a * (1 - newColor.a)) /
		(newColor.a + oldColor.a * (1 - newColor.a));
	toReturn.a = newColor.a + oldColor.a * (1 - newColor.a);
	return toReturn;
}

vec4 blendMultiply(vec4 oldColor, vec4 newColor)
{
	return oldColor * newColor;
}

vec4 blendAdd(vec4 oldColor, vec4 newColor)
{
	return oldColor + newColor;
}

vec4 blendSubtract(vec4 oldColor, vec4 newColor)
{
	return oldColor - newColor;
}

/*
vec3 rgb2hsv(vec3 c)
{
    vec4 K = vec4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);
    //vec4 p = mix(vec4(c.bg, K.wz), vec4(c.gb, K.xy), step(c.b, c.g));
    //vec4 q = mix(vec4(p.xyw, c.r), vec4(c.r, p.yzx), step(p.x, c.r));
	vec4 p = c.g < c.b ? vec4(c.bg, K.wz) : vec4(c.gb, K.xy);
    vec4 q = c.r < p.x ? vec4(p.xyw, c.r) : vec4(c.r, p.yzx);

    float d = q.x - min(q.w, q.y);
    float e = 1.0e-10;
    return vec3(abs(q.z + (q.w - q.y) / (6.0 * d + e)), d / (q.x + e), q.x);
}

vec3 hsv2rgb(vec3 c)
{
    vec4 K = vec4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);
    vec3 p = abs(fract(c.xxx + K.xyz) * 6.0 - K.www);
    return c.z * mix(K.xxx, clamp(p - K.xxx, 0.0, 1.0), c.y);
}
*/

vec3 hsl2rgb( in vec3 c )
{
    vec3 rgb = clamp( abs(mod(c.x*6.0+vec3(0.0,4.0,2.0),6.0)-3.0)-1.0, 0.0, 1.0 );

    return c.z + c.y * (rgb-0.5)*(1.0-abs(2.0*c.z-1.0));
}

vec3 HueShift (in vec3 Color, in float Shift)
{
    vec3 P = vec3(0.55735)*dot(vec3(0.55735),Color);
    
    vec3 U = Color-P;
    
    vec3 V = cross(vec3(0.55735),U);    

    Color = U*cos(Shift*6.2832) + V*sin(Shift*6.2832) + P;
    
    return vec3(Color);
}

vec3 rgb2hsl( in vec3 c ){
  float h = 0.0;
	float s = 0.0;
	float l = 0.0;
	float r = c.r;
	float g = c.g;
	float b = c.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 ) ); Original
		s = l < .0 ? cDelta / ( cMax + cMin ) : cDelta / ( 2.0 - ( cMax + cMin ) );
        
		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 );
}

vec3 rgb2hsv(vec3 c)
{
    vec4 K = vec4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);
    //vec4 p = mix(vec4(c.bg, K.wz), vec4(c.gb, K.xy), step(c.b, c.g));
    //vec4 q = mix(vec4(p.xyw, c.r), vec4(c.r, p.yzx), step(p.x, c.r));
	vec4 p = c.g < c.b ? vec4(c.bg, K.wz) : vec4(c.gb, K.xy);
    vec4 q = c.r < p.x ? vec4(p.xyw, c.r) : vec4(c.r, p.yzx);

    float d = q.x - min(q.w, q.y);
    float e = 1.0e-10;
    return vec3(abs(q.z + (q.w - q.y) / (6.0 * d + e)), d / (q.x + e), q.x);
}

vec3 hsv2rgb(vec3 c)
{
    vec4 K = vec4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);
    vec3 p = abs(fract(c.xxx + K.xyz) * 6.0 - K.www);
    return c.z * mix(K.xxx, clamp(p - K.xxx, 0.0, 1.0), c.y);
}

#endif