// Copyright Epic Games, Inc. All Rights Reserved.
//------------------------------------------------------------------------------
// Copyright (c) 2021 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.
//------------------------------------------------------------------------------

// FidelityFX Super Resolution - Robust Contrast Adaptive Sharpening

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


// =====================================================================================
//
// SHADER RESOURCES
//
// =====================================================================================

// RCAS params
uint4 Const0;
float2 VPColor_ExtentInverse;


// =====================================================================================
//
// FIDELITYFX SETUP
//
// =====================================================================================
#define A_HLSL 1
#define A_GPU  1

#if USE_RCAS_DENOISE 
#define FSR_RCAS_DENOISE 1
#endif

#if USE_PASSTHROUGH_ALPHA
#define FSR_RCAS_PASSTHROUGH_ALPHA 1
#endif

#if ENABLE_FP16
	#define FSR_RCAS_H   1
	#define FSR_RCAS_HX2 1
	#define A_HALF       1
	#include "ffx_a.ush"

	Texture2D<AH4>   InputTexture;
	RWTexture2D<AH4> OutputTexture;
	AH4 FsrRcasLoadH(min16int2 p)  {return InputTexture.Load(int3(p, 0));}
	AH4 FsrRcasLoadHx2(min16int2 p){return InputTexture.Load(int3(p, 0));}
#else
	#define FSR_RCAS_F 1
	#include "ffx_a.ush"

	Texture2D           InputTexture;
	RWTexture2D<float4> OutputTexture;
	AF4 FsrRcasLoadF(int2 p){return InputTexture.Load(int3(p, 0));}
#endif
	
// should be included after ffx_a.ush, defines FSR_OUTPUTDEVICE
#include "PostProcessMobileFFX_Common.ush"


// Note: Input is expected to be in Gamma2-encoding.
// LDR: This is already the case.
// HDR: A ColorConversionCS runs before FSR to provide Gamma2 input to FSR passes
#if ENABLE_FP16
	void FsrRcasInputH  (inout AH1 r,inout AH1 g,inout AH1 b){} // RCAS is done in perceptual space (sRGB~Gamma2)
	void FsrRcasInputHx2(inout AH2 r,inout AH2 g,inout AH2 b){} // Hence, no need to modify r/g/b
#else
	void FsrRcasInputF(inout AF1 r, inout AF1 g, inout AF1 b){}
#endif


#include "ffx_fsr1.ush"


// =====================================================================================
// 
// RCAS IMPLEMENTATION
// 
// =====================================================================================
#if ENABLE_FP16 // half precision floating point
AH4 RCASPassCommon(AU2 gxy)
#else
AF4 RCASPassCommon(AU2 gxy)
#endif
{
	//
	// RCAS()
	//
	#if ENABLE_FP16 // half precision floating point

		#if USE_PASSTHROUGH_ALPHA

			AH4 Gamma2Color = AH4(0, 0, 0, 0);
			FsrRcasH(Gamma2Color.r, Gamma2Color.g, Gamma2Color.b, Gamma2Color.a, gxy, Const0);
	
		#else
	
			AH4 Gamma2Color = AH4(0, 0, 0, 1);
			FsrRcasH(Gamma2Color.r, Gamma2Color.g, Gamma2Color.b, gxy, Const0);
	
		#endif // USE_PASSTHROUGH_ALPHA
	
	#else // FP32 - full precision floating point

		#if USE_PASSTHROUGH_ALPHA
	
			AF4 Gamma2Color = AF4(0, 0, 0, 0);
			FsrRcasF(Gamma2Color.r, Gamma2Color.g, Gamma2Color.b, Gamma2Color.a, gxy, Const0);
	
		#else
	
			AF4 Gamma2Color = AF4(0, 0, 0, 1);
			FsrRcasF(Gamma2Color.r, Gamma2Color.g, Gamma2Color.b, gxy, Const0);
	
		#endif // USE_PASSTHROUGH_ALPHA
	
	#endif // ENABLE_FP16

	return Gamma2Color;
}



// =====================================================================================
//
// ENTRY POINTS
//
// =====================================================================================
#if COMPUTE_SHADER
[numthreads(THREADGROUP_SIZEX, THREADGROUP_SIZEY, THREADGROUP_SIZEZ)]
void MainCS(uint3 LocalThreadId : SV_GroupThreadID, uint3 WorkGroupId : SV_GroupID, uint3 Dtid : SV_DispatchThreadID)
{
	// Do remapping of local xy in workgroup for a more PS-like swizzle pattern.
	AU2 gxy = ARmp8x8(LocalThreadId.x) + AU2(WorkGroupId.x << 4u, WorkGroupId.y << 4u);	
	
#if ENABLE_FP16
	OutputTexture[gxy] = RCASPassCommon(gxy);

	gxy.x += 8u;
	OutputTexture[gxy] = RCASPassCommon(gxy);

	gxy.y += 8u;
	OutputTexture[gxy] = RCASPassCommon(gxy);

	gxy.x -= 8u;
	OutputTexture[gxy] = RCASPassCommon(gxy);
#else
	OutputTexture[gxy] = RCASPassCommon(gxy);

	gxy.x += 8u;
	OutputTexture[gxy] = RCASPassCommon(gxy);

	gxy.y += 8u;
	OutputTexture[gxy] = RCASPassCommon(gxy);

	gxy.x -= 8u;
	OutputTexture[gxy] = RCASPassCommon(gxy);
#endif
}
#endif // COMPUTE_SHADER

#if ENABLE_FP16
void MainPS(noperspective float4 UVAndScreenPos : TEXCOORD0, float4 SvPosition : SV_POSITION, out AH4 OutColor : SV_Target0)
{
	AU2 gxy = AU2(SvPosition.xy);
	OutColor = RCASPassCommon(gxy);
}
#else
void MainPS(noperspective float4 UVAndScreenPos : TEXCOORD0, float4 SvPosition : SV_POSITION, out float4 OutColor : SV_Target0)
{
	AU2 gxy = AU2(SvPosition.xy);
	OutColor = RCASPassCommon(gxy);
}
#endif