// Copyright 2022 Manuel Wagner - All rights reserved

Texture2D InputTexture;
SamplerState InputTextureSampler;
RWBuffer<float> OutputUAV;
uint2 OutputDimensions; // X = InputTensor.GetSize(1), Y = InputTensor.GetSize(2) -> this does not correspond to input texture XY
float2 HalfPixelUV;

[numthreads(THREADGROUP_SIZE_X, THREADGROUP_SIZE_Y, THREADGROUP_SIZE_Z)]
void SceneColorToInputTensorCS(in const uint3 DispatchThreadID : SV_DispatchThreadID)
{
	const uint2 OutputUAVTexelCoordinate = DispatchThreadID.xy;
	if(any(OutputUAVTexelCoordinate >= OutputDimensions))
	{
		return;
	}

	const uint GlobalIndex = ((OutputUAVTexelCoordinate.x * OutputDimensions.y  + OutputUAVTexelCoordinate.y)*3);

	// note that the OutputUAV has shape (1, Y, X, C)
	// which is why we need to flip the indexing
	const float2 UV = float2(OutputUAVTexelCoordinate.yx) / float2(OutputDimensions.yx) + HalfPixelUV;

	const float4 TextureValue = InputTexture.SampleLevel(InputTextureSampler, UV, 0);

	OutputUAV[GlobalIndex + 0] = TextureValue.r;
	OutputUAV[GlobalIndex + 1] = TextureValue.g;
	OutputUAV[GlobalIndex + 2] = TextureValue.b;
}

#include "/Engine/Public/Platform.ush"