UnrealEngineUWP/Engine/Shaders/PostProcessBusyWait.usf

// Copyright 1998-2014 Epic Games, Inc. All Rights Reserved.

/*=============================================================================
	PostProcessBusyWait.usf: Post processing busy wait implementation. For Debugging GPU timing.
=============================================================================*/

#include "Common.usf"
#include "PostProcessCommon.usf"

// >0, from the console variable r.GPUBusyWait, multiplied with some factor
uint GPUBusyWait;

void MainPS(float4 UVAndScreenPos : TEXCOORD0, out float4 OutColor : SV_Target0)
{
	float2 UV = UVAndScreenPos.xy;

	float Value = UV.x;

	for(uint i = 0; i < GPUBusyWait; ++i)
	{
		Value = Value * Value - 2.0f; 
	}

	OutColor = Value * 0.000000001f;
}