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

#include "Common.ush"
#include "ScreenPass.ush"
#include "PostProcessHistogramCommon.ush"

SCREEN_PASS_TEXTURE_VIEWPORT(Input)
Texture2D InputTexture;

RWTexture2D<float> Output2DFRW;

[numthreads(THREADGROUP_SIZEX, THREADGROUP_SIZEY, 1)]
void SetupLogLuminanceCS(uint3 DispatchThreadId : SV_DispatchThreadID)
{
	float3 SceneColor = InputTexture.Load(uint3(Input_ViewportMin + DispatchThreadId.xy, 0)).rgb * View.OneOverPreExposure;
	float LuminanceVal = CalculateEyeAdaptationLuminance(SceneColor);
	Output2DFRW[DispatchThreadId.xy] = log2(LuminanceVal);
}