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

#include "/Engine/Private/Common.ush"
#include "/Engine/Shared/MaterialCacheDefinitions.h"
#include "/Engine/Private/GammaCorrectionCommon.ush"
#include "/Engine/Private/MortonCode.ush"

StructuredBuffer<FMaterialCachePageWriteData> PageWriteData;

RWTexture2D<float4> RWVTLayer0;
RWTexture2D<float4> RWVTLayer1;
RWTexture2D<float4> RWVTLayer2;

Texture2DArray<float4> ABuffer0;
Texture2DArray<float4> ABuffer1;
Texture2DArray<float4> ABuffer2;

[numthreads(64, 1, 1)]
void WritePagesMain(uint3 DTid : SV_DispatchThreadID)
{
	const FMaterialCachePageWriteData Data = PageWriteData[DTid.y];

	// Tile width guaranteed to be power of two, Morton is fine
	const uint2 PagePixelPos = MortonDecode(DTid.x);
	
	const uint3 ABufferPhysicalLocation = Data.ABufferPhysicalPosition + uint3(PagePixelPos, 0);
	const uint2 VTPhysicalLocation      = Data.VTPhysicalPosition + PagePixelPos;

	float4 ABufferValue0 = ABuffer0[ABufferPhysicalLocation];
	float4 ABufferValue1 = ABuffer1[ABufferPhysicalLocation];
	float4 ABufferValue2 = ABuffer2[ABufferPhysicalLocation];

	// -- Platform Block Compression --
	
	RWVTLayer0[VTPhysicalLocation] = float4(LinearToSrgb(ABufferValue0.xyz), ABufferValue0.w);
	RWVTLayer1[VTPhysicalLocation] = ABufferValue1;
	RWVTLayer2[VTPhysicalLocation] = ABufferValue2;
}