Lumen.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "EngineDefines.h"
#include "HAL/LowLevelMemTracker.h"
#include "Math/Vector.h"
#include "RHIShaderPlatform.h"
 
class FScene;
class FSceneView;
class FSceneViewFamily;
class FViewFamilyInfo;
class FViewInfo;
struct FEngineShowFlags;
enum class EDiffuseIndirectMethod;
struct FScreenMessageWriter;
enum EPixelFormat : uint8;
 
extern bool ShouldRenderLumenDiffuseGI(const FScene* Scene, const FSceneView& View, bool bSkipTracingDataCheck = false, bool bSkipProjectCheck = false);
extern bool ShouldRenderLumenReflections(const FSceneView& View, bool bSkipTracingDataCheck = false, bool bSkipProjectCheck = false, bool bIncludeStandalone = true);
extern bool ShouldRenderLumenReflectionsWater(const FViewInfo& View, bool bSkipTracingDataCheck = false, bool bSkipProjectCheck = false);
extern bool ShouldRenderLumenDirectLighting(const FScene* Scene, const FSceneView& View);
extern bool ShouldRenderAOWithLumenGI();
extern bool ShouldUseStereoLumenOptimizations();
 
 
class FLumenSceneData;
 
inline double BoxSurfaceArea(FVector Extent)
{
    return 2.0 * (Extent.X * Extent.Y + Extent.Y * Extent.Z + Extent.Z * Extent.X);
}
 
namespace Lumen
{
    // Must match usf
    constexpr uint32 PhysicalPageSize = 128;
    constexpr uint32 VirtualPageSize = PhysicalPageSize - 1; // 0.5 texel border around page
    constexpr uint32 MinCardResolution = 8;
    constexpr uint32 MinResLevel = 3; // 2^3 = MinCardResolution
    constexpr uint32 MaxResLevel = 11; // 2^11 = 2048 texels
    constexpr uint32 SubAllocationResLevel = 7; // log2(PHYSICAL_PAGE_SIZE)
    constexpr uint32 NumResLevels = MaxResLevel - MinResLevel + 1;
    constexpr uint32 CardTileSize = 8;
    constexpr uint32 CardTileShadowDownsampleFactorDwords = 8;
    constexpr uint32 NumDistanceBuckets = 16;
 
    constexpr float MaxTraceDistance = 0.5f * UE_OLD_WORLD_MAX;
 
    enum class ETracingPermutation
    {
        Cards,
        VoxelsAfterCards,
        Voxels,
        MAX
    };
 
    void DebugResetSurfaceCache();
 
    float GetMaxTraceDistance(const FViewInfo& View);
    bool IsLumenFeatureAllowedForView(const FScene* Scene, const FSceneView& View, bool bSkipTracingDataCheck = false, bool bSkipProjectCheck = false);
    bool ShouldVisualizeScene(const FEngineShowFlags& ShowFlags);
    bool ShouldVisualizeHardwareRayTracing(const FSceneViewFamily& ViewFamily);
    bool ShouldHandleSkyLight(const FScene* Scene, const FSceneViewFamily& ViewFamily);
 
    bool ShouldUpdateLumenSceneViewOrigin();
    FVector GetLumenSceneViewOrigin(const FViewInfo& View, int32 ClipmapIndex);
 
    // Global Distance Field
    int32 GetGlobalDFResolution();
    float GetGlobalDFClipmapExtent(int32 ClipmapIndex);
    int32 GetNumGlobalDFClipmaps(const FSceneView& View);
 
    // Features
    bool UseAsyncCompute(const FViewFamilyInfo& ViewFamily);
    bool UseWaveOps(EShaderPlatform ShaderPlatform);
    bool UseThreadGroupSize32();
    EPixelFormat GetLightingDataFormat();
    FVector3f GetLightingQuantizationError();
    float GetCachedLightingPreExposure();
 
    // Surface cache
    bool IsSurfaceCacheFrozen();
    bool IsSurfaceCacheUpdateFrameFrozen();
 
    // Software ray tracing
    bool IsSoftwareRayTracingSupported();
    bool UseMeshSDFTracing(const FEngineShowFlags& EngineShowFlags);
    bool UseGlobalSDFTracing(const FEngineShowFlags& EngineShowFlags);
    bool UseGlobalSDFSimpleCoverageBasedExpand();
    bool UseGlobalSDFObjectGrid(const FSceneViewFamily& ViewFamily);
    bool UseHeightfieldTracing(const FSceneViewFamily& ViewFamily, const FLumenSceneData& LumenSceneData);
    bool UseHeightfieldTracingForVoxelLighting(const FLumenSceneData& LumenSceneData);
    int32 GetHeightfieldMaxTracingSteps();
    bool IsUsingGlobalSDF(const FSceneViewFamily& ViewFamily);
    bool IsUsingDistanceFieldRepresentationBit(const FViewInfo& View);
 
    // Hardware ray tracing
    bool AnyLumenHardwareRayTracingPassEnabled(const FScene* Scene, const FViewInfo& View);
    bool AnyLumenHardwareInlineRayTracingPassEnabled(const FScene* Scene, const FViewInfo& View);
    bool UseHardwareRayTracing(const FSceneViewFamily& ViewFamily);
    bool UseHardwareRayTracedSceneLighting(const FSceneViewFamily& ViewFamily);
    bool UseHardwareRayTracedDirectLighting(const FSceneViewFamily& ViewFamily);
    bool UseHardwareRayTracedReflections(const FSceneViewFamily& ViewFamily);
    bool UseReSTIRGather(const FSceneViewFamily& ViewFamily, EShaderPlatform ShaderPlatform);
    bool UseHardwareRayTracedScreenProbeGather(const FSceneViewFamily& ViewFamily);
    bool UseHardwareRayTracedShortRangeAO(const FSceneViewFamily& ViewFamily);
    bool UseHardwareRayTracedRadianceCache(const FSceneViewFamily& ViewFamily);
    bool UseHardwareRayTracedRadiosity(const FSceneViewFamily& ViewFamily);
    bool UseHardwareRayTracedVisualize(const FSceneViewFamily& ViewFamily);
    bool IsUsingRayTracingLightingGrid(const FSceneViewFamily& ViewFamily, const FViewInfo& View, EDiffuseIndirectMethod DiffuseIndirectMethod);
 
    bool ShouldRenderRadiosityHardwareRayTracing(const FSceneViewFamily& ViewFamily);
    bool ShouldVisualizeHardwareRayTracing(const FSceneViewFamily& ViewFamily);
 
    bool ShouldPrecachePSOs(EShaderPlatform Platform);
    
    bool UseHardwareInlineRayTracing(const FSceneViewFamily& ViewFamily);
 
    enum class ESurfaceCacheSampling
    {
        AlwaysResidentPagesWithoutFeedback,
        AlwaysResidentPages,
        HighResPages,
    };
 
    float GetHardwareRayTracingPullbackBias();
 
    bool UseFarField(const FSceneViewFamily& ViewFamily);
    bool UseFarFieldOcclusionOnly();
    float GetFarFieldMaxTraceDistance();
    float GetNearFieldMaxTraceDistanceDitherScale(bool bUseFarField);
    float GetNearFieldSceneRadius(const FViewInfo& View, bool bUseFarField);
 
    uint32 GetMeshCardDistanceBin(float Distance);
 
    float GetHeightfieldReceiverBias();
    void Shutdown();
 
    bool WriteWarnings(const FScene* Scene, const FEngineShowFlags& ShowFlags, const TArray<FViewInfo>& Views, FScreenMessageWriter* Writer);
 
    bool SupportsMultipleClosureEvaluation(EShaderPlatform ShaderPlatform);
    bool SupportsMultipleClosureEvaluation(const FViewInfo& View);
};
 
extern int32 GLumenFastCameraMode;
 
LLM_DECLARE_TAG(Lumen);