// This file is part of the FidelityFX Super Resolution 3.1 Unreal Engine Plugin.
//
// Copyright (c) 2023-2025 Advanced Micro Devices, Inc. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

#include "/Engine/Private/Common.ush"
#include "/Engine/Private/ScreenPass.ush"

static const half InvDistortionScaleBias = 1 / 4.0f;

// =====================================================================================
//
// SHADER RESOURCES
//
// =====================================================================================
Texture2D UEDistortion;
RWTexture2D<half2> OutputTexture;

// =====================================================================================
//
// ENTRY POINTS
//
// =====================================================================================
[numthreads(THREADGROUP_SIZEX, THREADGROUP_SIZEY, THREADGROUP_SIZEZ)] 
void MainCS(uint3 LocalThreadId : SV_GroupThreadID, uint3 WorkGroupId : SV_GroupID, uint3 DispatchThreadId : SV_DispatchThreadID)
{
	uint Width = View.ViewSizeAndInvSize.x;
	uint Height = View.ViewSizeAndInvSize.y;

	if (Width > DispatchThreadId.x && Height > DispatchThreadId.y)
	{
		half2 PositiveOffset = UEDistortion[DispatchThreadId.xy + View.ViewRectMin.xy].rg;
		half2 NegativeOffset = UEDistortion[DispatchThreadId.xy + View.ViewRectMin.xy].ba;
		OutputTexture[DispatchThreadId.xy] = (PositiveOffset - NegativeOffset) * InvDistortionScaleBias;
	}
}