UnrealEngineUWP/Engine/Shaders/InstancedStereo.usf

// Copyright 1998-2017 Epic Games, Inc. All Rights Reserved..

/*=============================================================================
	InstancedStereo.usf: Resolve which view uniforms in a stereo pair to use.
=============================================================================*/

#pragma once

// Explictly include view uniform buffers
#include "UniformBuffers/View.usf"
#include "UniformBuffers/InstancedView.usf"

// ViewState, GetPrimaryView and GetInstancedView are generated by the shader compiler to ensure View uniform buffer changes are up to date.
// see GenerateInstancedStereoCode()
#include "GeneratedInstancedStereo.usf"

// Packing the eye index and instanced stereo flag into a single uint to save an interpolator
uint PackEyeIndex(uint EyeIndex, bool bIsInstancedStereo)
{
	uint Result = 0;
	Result |= (uint)bIsInstancedStereo << 31;
	Result |= EyeIndex;
	return Result;
}

uint GetEyeIndex(uint PackedIndex)
{
	return PackedIndex & 0x1;
}

bool IsInstancedStereo(uint PackedIndex)
{
	return (PackedIndex >> 1) > 0;
}

static ViewState ResolvedView;

ViewState ResolveView()
{
	return GetPrimaryView();
}

#if INSTANCED_STEREO
static const float EyeOffsetScale[2] = { -1.0, 1.0 };
static const float4 EyeClipEdge[2] = { float4(-1.0, 0.0, 0.0, 1.0), float4(1.0, 0.0, 0.0, 1.0) };
bool bIsInstancedStereo;
#endif

#if INSTANCED_STEREO || MOBILE_MULTI_VIEW
ViewState ResolveView(uint ViewIndex)
{
	if (ViewIndex == 0)
	{
		return GetPrimaryView();
	}
	else
	{
		return GetInstancedView();
	}
}
#endif