UnrealEngineUWP/Engine/Shaders/Private/SlatePostProcessPixelShader.usf

// Copyright Epic Games, Inc. All Rights Reserved.

#include "Common.ush"
#include "SlateShaderCommon.ush"


#define BILINEAR_FILTER_METHOD 1
#define MAX_SAMPLES 127

#if BILINEAR_FILTER_METHOD

// Weigts and offsets are packed into 4 floats (Weight, Offset, Weight, Offset)
float4 WeightAndOffsets[MAX_SAMPLES/2];
#else

#define MAX_SAMPLES 127
// Weigts and offsets are packed into 4 floats (Weight, Offset, Weight, Offset)
float4 WeightAndOffsets[MAX_SAMPLES];

#endif

/** Blur sample count */
int SampleCount;


Texture2D ElementTexture;
SamplerState ElementTextureSampler;

float4 BufferSizeAndDirection;
float4 UVBounds;
float4 ShaderParams;
float4 ShaderParams2;

float4 GetSample(float Weight, float Offset, float2 UV)
{
	const float2 MinUV = UVBounds.xy;
	const float2 MaxUV = UVBounds.zw;
	const float2 Direction = BufferSizeAndDirection.zw;
	const float2 BufferSize = BufferSizeAndDirection.xy;
	const float2 UVOffset = float2(Offset*BufferSize.x*Direction.x, Offset*BufferSize.y*Direction.y);

	return 
		Texture2DSample(ElementTexture, ElementTextureSampler, clamp(UV + UVOffset, MinUV, MaxUV)) * Weight
		+ Texture2DSample(ElementTexture, ElementTextureSampler, clamp(UV - UVOffset, MinUV, MaxUV)) * Weight;
}

float4 GaussianBlurMain( FScreenVertexOutput Input ) : SV_Target0
{
#if 0
	float4 OutColor = Texture2DSample(ElementTexture, ElementTextureSampler, Input.UV);
#else

	float4 OutColor = Texture2DSample(ElementTexture, ElementTextureSampler, clamp(Input.UV, UVBounds.xy, UVBounds.zw)) * WeightAndOffsets[0].x;
	// First offset is in zw
	{
		float Weight = WeightAndOffsets[0].z;
		float Offset = WeightAndOffsets[0].w;

		OutColor += GetSample(Weight, Offset, Input.UV);
	}

	for (int i = 2; i<SampleCount; i+=2)
	{
		int Index = i/2;
		{
			float Weight = WeightAndOffsets[Index].x;
			float Offset = WeightAndOffsets[Index].y;

			OutColor += GetSample(Weight, Offset, Input.UV);
		}

		{
			float Weight = WeightAndOffsets[Index].z;
			float Offset = WeightAndOffsets[Index].w;

			OutColor += GetSample(Weight, Offset, Input.UV);
		}

	}
#endif

	return float4(OutColor.rgb, 1);
}

float4 DownsampleMain(FScreenVertexOutput Input) : SV_Target0
{
#if 0
	return Texture2DSample(ElementTexture, ElementTextureSampler, Input.UV);
#else

	float2 UV[4];

	float2 MinUV = UVBounds.xy;
	float2 MaxUV = UVBounds.zw;

	// Shader params X/Y stores the UV offset in each direction
	UV[0] = clamp(Input.UV + ShaderParams.xy * float2(-1, -1), MinUV, MaxUV);
	UV[1] = clamp(Input.UV + ShaderParams.xy * float2(1, -1), MinUV, MaxUV);
	UV[2] = clamp(Input.UV + ShaderParams.xy * float2(-1, 1), MinUV, MaxUV);
	UV[3] = clamp(Input.UV + ShaderParams.xy * float2(1, 1), MinUV, MaxUV);

	float4 Sample[4];

	UNROLL for(int i = 0; i < 4; ++i)
	{
		Sample[i] = Texture2DSample(ElementTexture, ElementTextureSampler, UV[i]);
	}

	return float4(Sample[0] + Sample[1] + Sample[2] + Sample[3]) * 0.25f;
#endif
}

float2 Map(float2 value, float2 min1, float2 max1, float2 min2, float2 max2)
{
  return min2 + (value - min1) * (max2 - min2) / (max1 - min1);
}

float4 UpsampleMain(FScreenVertexOutput Input) : SV_Target0
{
	const float2 LocalSize = ShaderParams.xy;
	const float2 UV = Input.UV;
	const float Thickness = 0;
	const float4 CornerRadii = ShaderParams2;
	const float4 FillColor = Texture2DSample(ElementTexture, ElementTextureSampler, Input.UV);
	return GetRoundedBoxElementColorInternal(LocalSize, Map(UV, float2(0,0), ShaderParams.zw, float2(0,0),float2(1,1)), Thickness, CornerRadii, FillColor, FillColor);
}