ScriptableRenderPipeline/MaterialGraphProject/Assets/UnityShaderEditor/Runtime/Nodes/Art/Conversion/RGBtoHSVNode.cs

using System.Reflection;

namespace UnityEngine.MaterialGraph
{
	[Title ("Art/Conversion/RGBtoHSV")]
	public class RGBtoHSVNode : CodeFunctionNode
	{
		public RGBtoHSVNode ()
		{
			name = "RGBtoHSV";
		}

	    protected override MethodInfo GetFunctionToConvert()
	    {
	        return GetType().GetMethod("Unity_RGBtoHSV", BindingFlags.Static | BindingFlags.NonPublic);
	    }

	    static string Unity_RGBtoHSV(
	        [Slot(0, Binding.None)] Vector3 rgb,
	        [Slot(1, Binding.None)] out Vector3 hsv)
	    {
	        hsv = Vector3.zero;
	        return
	            @"
{
    //Reference code from:http://www.chilliant.com/rgb2hsv.html
    {precision}4 K = {precision}4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);
    {precision}4 P = lerp({precision}4(rgb.bg, K.wz), {precision}4(rgb.gb, K.xy), step(rgb.b, rgb.g));
    {precision}4 Q = lerp({precision}4(P.xyw, rgb.r), {precision}4(rgb.r, P.yzx), step(P.x, rgb.r));
    {precision} D = Q.x - min(Q.w, Q.y);
    {precision}  E = 1e-10;
    hsv = {precision}3(abs(Q.z + (Q.w - Q.y)/(6.0 * D + E)), D / (Q.x + E), Q.x);
}
";
	    }
	}
}