Lightmass misc lightmapping notes

StaticLightingDebug.cpp:::What goodies lie here?

LightaMapRendering (in Renderer Module): Handles render thread side of lightmaps (setting/creating uniform buffers)

FLightmap/FlightMap2D

  • GameThread struct containing lightmap data
  • Contains a reference (LightmapSetBelongsTo) to the lightmap set this lightmap refers to
  • LightmapSetBelongsTo set when FLightMap struct is allocated
  • Components handle allocating the FLightmap bookkepping data
  • Stores references to actual textures for the lightmaps

FLightMapInteraction

  • Defines interaction between mesh & lightmap
  • Just stores references to the textures in FlightMap + coefficients
  • Value struct b/c it gets blitted to the render thread

Registry->AllocateMeshBuildData

  • This actually creates the MeshMapBuildData struct
  • This gets written out to a sideband package next to the level (ex: MyHellzoneLevel_BuildData)

FLightMap2D::AllocateLightMap/FLightMap2D::AllocateInstancedLightMap

  • Seems to be called during light builds only
  • Actually allocates the lightmap texture

Components that require static lighting interaction (ex: landscape or staticmesh) have follow this file convention

  • [ComponentName]Lighting.cpp handles lightmapping functionality
  • [ComponentName]Rendering.cpp handles rendering

High-level process of baking

Start with StaticLightingManager::UpdateBuildLighting

AllocateLightMap populates PendingLightMaps (static array<FlightMapAllocationGroup> that gets procesed during Encode)

FlightMapAllocationGroup: Container of set of FLightMapAllocation

FlightMapAllocationGroup: Allocation of a region of lightmap texture to a specific lightmap

EncodeTextures() takes all the data in the PendingLightMaps allocation groups and turns them into FLightMapPendingTexture

FLightMapPendingTexture::StartEncoding()

Multiple Lightmaps

r.HighQualityLightMaps

TODO:

grep GCurrentLightmapSetIndex

grep LightmapSets

grep GCurrentILCIndex

add suffix to engine modification tag @third party code - Bebylon - MultiLightmap

coalesce cvars & rename to be better

change forward pass to use precomputed lightmap blends

store reference to MeshMapBuildDataID for LightmapSetsBelongTo

rename references of TArray<FLightMapRef> to typedef TArray<FLightMapRef> Lightmapset

FVector PrecomputedLightVolumeOffset = InWorldOffset - FVector(LightBuildLevelOffset);

PrecomputedLightVolume->ApplyWorldOffset(PrecomputedLightVolumeOffset);

void ULevel::OnApplyNewLightingData(bool bLightingSuccessful)

{

// Store level offset that was used during static light data build

// This will be used to find correct world position of precomputed lighting samples during origin rebasing

LightBuildLevelOffset = FIntVector::ZeroValue;

if (bLightingSuccessful && OwningWorld && OwningWorld->WorldComposition)

{

LightBuildLevelOffset = OwningWorld->WorldComposition->GetLevelOffset(this);

}

}

ULightComponent::IsPrecomputedLightingValid()


Last update: November 14, 2019