/*
 Denoising by NVIDIA Corporation
 https://a248.e.akamai.net/f/248/10/10/developer.download.nvidia.com/SDK/10/direct3d/screenshots/samples/Denoising.html
 
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 Modified and optimized for ReShade by JPulowski

 Do not distribute without giving credit to the original author(s).

 1.0  - Initial release
*/
#include EFFECT_CONFIG(JPulowski)

#if USE_DENOISE

#pragma message "Denoise by NVIDIA (ported by JPulowski)\n"

namespace JPulowski {

float3 PS_Denoise_KNN(float4 vpos : SV_POSITION, float2 texcoord : TEXCOORD0) : SV_TARGET
{
	float3 orig = tex2D(ReShade::BackBuffer, texcoord).rgb;
	float3 texIJ;
	float weight;
	float3 result = 0.0;
	float counter = 0.0;
	float sum = 0.0;
	
	float iWindowArea = 2.0 * WindowRadius + 1.0;
	iWindowArea *= iWindowArea;
	
	for (int i = -WindowRadius; i <= WindowRadius; i++) {
		for (int j = -WindowRadius; j <= WindowRadius; j++) {                       
			texIJ = tex2D(ReShade::BackBuffer, texcoord + ReShade::PixelSize * float2(i, j)).rgb;
			weight = dot(orig - texIJ, orig - texIJ);

			weight = exp(-(weight * rcp(NoiseLevel) + (i * i + j * j) * rcp(GaussianSigma)));
			counter += weight > WeightThreshold;
			
			sum += weight;
			
			result.rgb += texIJ * weight;
		}
	}
            
	result /= sum;
	float lerpQ = (counter > (CounterThreshold * iWindowArea)) ? 1.0 - LerpCoefficeint : LerpCoefficeint;
	result = lerp(result, orig, lerpQ);
	
	return result;
}

float3 PS_Denoise_NLM(float4 vpos : SV_POSITION, float2 texcoord : TEXCOORD0) : SV_TARGET
{
	float3 result = 0.0;
	float3 texIJb;
	float3 texIJc;
	float counter = 0.0;
	float weight;  
	float sum = 0.0;
    
	float invBlockArea = 2.0 * BlockRadius + 1.0;
	invBlockArea = rcp(invBlockArea * invBlockArea);
    
	for (int i = -WindowRadius; i <= WindowRadius; i++) {
        for (int j = -WindowRadius; j <= WindowRadius; j++) {
				
				weight = 0.0;
				
				for (int n = -BlockRadius; n <= BlockRadius; n++) {
					for (int m = -BlockRadius; m <= BlockRadius; m++) {              
							texIJb = tex2D(ReShade::BackBuffer, texcoord + ReShade::PixelSize * float2(i + n, j + m)).rgb;
							texIJc = tex2D(ReShade::BackBuffer, texcoord + ReShade::PixelSize * float2(    n,     m)).rgb;
							weight = dot(texIJb - texIJc, texIJb - texIJc) + weight;
					}
                }
				texIJc = tex2D(ReShade::BackBuffer, texcoord + ReShade::PixelSize * float2(i, j)).rgb;

				weight *= invBlockArea;
				weight = exp(-(weight * rcp(NoiseLevel) + (i * i + j * j) * rcp(GaussianSigma)));
	            
				counter += weight > WeightThreshold;

				sum += weight;

				result += texIJc * weight;
        }
	}
	float iWindowArea = 2.0 * WindowRadius + 1.0;
	iWindowArea *= iWindowArea;

	float3 orig = tex2D(ReShade::BackBuffer, texcoord).rgb;

    result /= sum;
	float lerpQ = (counter > (CounterThreshold * iWindowArea)) ? 1.0 - LerpCoefficeint : LerpCoefficeint;
	result = lerp(result, orig, lerpQ);
    
	return result;
}

technique Denoise_Tech <bool enabled = RESHADE_START_ENABLED; int toggle = Denoise_ToggleKey; >
{

#if (DenoiseMethod == 0)

	pass Bilateral
	{
		VertexShader = ReShade::VS_PostProcess;
		PixelShader = PS_Denoise_KNN;
	}

#else

	pass NonLocalMeans
	{
		VertexShader = ReShade::VS_PostProcess;
		PixelShader = PS_Denoise_NLM;
	}
	
#endif

}

}

#endif

#include EFFECT_CONFIG_UNDEF(JPulowski)
