RayTracingLighting.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "ShaderParameters.h"
#include "ShaderParameterMacros.h"
#include "SceneRendering.h"
#include "LightSceneInfo.h"
#include "RayTracingDefinitions.h"
#include "RayTracingTypes.h"
#include "Containers/DynamicRHIResourceArray.h"
 
#if RHI_RAYTRACING
 
FRHIRayTracingShader* GetRayTracingLightingMissShader(const FGlobalShaderMap* ShaderMap);
 
// This struct holds a light grid and list of raytracing lights for both building and rendering
BEGIN_GLOBAL_SHADER_PARAMETER_STRUCT(FRayTracingLightGrid, RENDERER_API)
    SHADER_PARAMETER(uint32, SceneLightCount)
    SHADER_PARAMETER(uint32, SceneInfiniteLightCount)
    SHADER_PARAMETER(FVector3f, SceneLightsTranslatedBoundMin)
    SHADER_PARAMETER(FVector3f, SceneLightsTranslatedBoundMax)
    SHADER_PARAMETER_RDG_BUFFER_SRV(StructuredBuffer<FRTLightingData>, SceneLights)
    SHADER_PARAMETER_RDG_TEXTURE(Texture2DArray<uint>, LightGrid)
    SHADER_PARAMETER_RDG_BUFFER_SRV(Buffer<uint>, LightGridData)
    SHADER_PARAMETER(unsigned, LightGridResolution)
    SHADER_PARAMETER(unsigned, LightGridMaxCount)
    SHADER_PARAMETER(unsigned, LightGridAxis)
END_GLOBAL_SHADER_PARAMETER_STRUCT()
 
using FRayTracingLightFunctionMap = TMap<const FLightSceneInfo*, int32>;
 
// Register this in the graph builder so we can easily move it around and access it from both the main rendering thread and RDG passes
RDG_REGISTER_BLACKBOARD_STRUCT(FRayTracingLightFunctionMap)
 
FRayTracingLightFunctionMap GatherLightFunctionLights(FScene* Scene, const FEngineShowFlags EngineShowFlags, ERHIFeatureLevel::Type InFeatureLevel);
FRayTracingLightFunctionMap GatherLightFunctionLightsPathTracing(FScene* Scene, const FEngineShowFlags EngineShowFlags, ERHIFeatureLevel::Type InFeatureLevel);
 
TRDGUniformBufferRef<FRayTracingLightGrid> CreateRayTracingLightData(
    FRDGBuilder& GraphBuilder,
    const FScene* Scene,
    const FSceneView& View,
    FGlobalShaderMap* ShaderMap,
    bool bBuildLightGrid);
 
void BindLightFunctionShaders(
    FRHICommandList& RHICmdList,
    const FScene* Scene,
    const FRayTracingLightFunctionMap* RayTracingLightFunctionMap,
    const class FViewInfo& View);
 
void BindLightFunctionShadersPathTracing(
    FRHICommandList& RHICmdList,
    const FScene* Scene,
    const FRayTracingLightFunctionMap* RayTracingLightFunctionMap,
    const class FViewInfo& View);
 
// Helper routines, useful when building a light grid
FBox3f GetPointLightBounds(const FVector3f& Center, float Radius);
FBox3f GetSpotLightBounds(const FVector3f& Center, const FVector3f& Normal, float Radius, float CosOuter);
FBox3f GetRectLightBounds(const FVector3f& Center, const FVector3f& Normal, const FVector3f& Tangent, float HalfWidth, float HalfHeight, float Radius, float BarnCos, float BarnLen);
 
#endif