RGB to HSV and vice versa (in shaders)

gistfile1.txt

	float3 Hue(float H)
	{
	  float R = abs(H * 6 - 3) - 1;
	  float G = 2 - abs(H * 6 - 2);
	  float B = 2 - abs(H * 6 - 4);
	  return saturate(float3(R,G,B));
	}

	float3 HSVtoRGB(in float3 HSV)
	{
	  return ((Hue(HSV.x) - 1) * HSV.y + 1) * HSV.z;
	}
	float3 RGBtoHSV(in float3 RGB)
	{
	    float3 HSV = 0;
	    HSV.z = max(RGB.r, max(RGB.g, RGB.b));
	    float M = min(RGB.r, min(RGB.g, RGB.b));
	    float C = HSV.z - M;
	    if (C != 0)
	    {
	        HSV.y = C / HSV.z;
	        float3 Delta = (HSV.z - RGB) / C;
	        Delta.rgb -= Delta.brg;
	        Delta.rg += float2(2,4);
	        if (RGB.r >= HSV.z)
	            HSV.x = Delta.b;
	        else if (RGB.g >= HSV.z)
	            HSV.x = Delta.r;
	        else
	            HSV.x = Delta.g;
	        HSV.x = frac(HSV.x / 6);
	    }
	    return HSV;
	}