LUT.fx

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// ReShade effect file
// visit facebook.com/MartyMcModding for news/updates
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// Marty's LUT shader 1.0 for ReShade 3.0
// Copyright © 2008-2016 Marty McFly
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#ifndef fLUT_TextureName
	#define fLUT_TextureName "lut.png"
#endif
#ifndef fLUT_TileSizeXY
	#define fLUT_TileSizeXY 32
#endif
#ifndef fLUT_TileAmount
	#define fLUT_TileAmount 32
#endif

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//
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#include "ReShadeUI.fxh"

uniform float fLUT_AmountChroma < __UNIFORM_SLIDER_FLOAT1
	ui_min = 0.00; ui_max = 1.00;
	ui_label = "LUT chroma amount";
	ui_tooltip = "Intensity of color/chroma change of the LUT.";
> = 1.00;

uniform float fLUT_AmountLuma < __UNIFORM_SLIDER_FLOAT1
	ui_min = 0.00; ui_max = 1.00;
	ui_label = "LUT luma amount";
	ui_tooltip = "Intensity of luma change of the LUT.";
> = 1.00;

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//
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#include "ReShade.fxh"
texture texLUT < source = fLUT_TextureName; > { Width = fLUT_TileSizeXY*fLUT_TileAmount; Height = fLUT_TileSizeXY; Format = RGBA8; };
sampler	SamplerLUT 	{ Texture = texLUT; };

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void PS_LUT_Apply(float4 vpos : SV_Position, float2 texcoord : TEXCOORD, out float4 res : SV_Target0)
{
	float4 color = tex2D(ReShade::BackBuffer, texcoord.xy);
	float2 texelsize = 1.0 / fLUT_TileSizeXY;
	texelsize.x /= fLUT_TileAmount;

	float3 lutcoord = float3((color.xy*fLUT_TileSizeXY-color.xy+0.5)*texelsize.xy,color.z*fLUT_TileSizeXY-color.z);
	float lerpfact = frac(lutcoord.z);
	lutcoord.x += (lutcoord.z-lerpfact)*texelsize.y;

	float3 lutcolor = lerp(tex2D(SamplerLUT, lutcoord.xy).xyz, tex2D(SamplerLUT, float2(lutcoord.x+texelsize.y,lutcoord.y)).xyz,lerpfact);

	color.xyz = lerp(normalize(color.xyz), normalize(lutcolor.xyz), fLUT_AmountChroma) * 
	            lerp(length(color.xyz),    length(lutcolor.xyz),    fLUT_AmountLuma);

	res.xyz = color.xyz;
	res.w = 1.0;
}

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//
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technique LUT
{
	pass LUT_Apply
	{
		VertexShader = PostProcessVS;
		PixelShader = PS_LUT_Apply;
	}
}