Layers, cameras and culling masks

Every GameObject has a layer from 0 to 31. A Camera (class 20) stores a culling mask, a 32-bit field with bit n set when the camera draws layer n, and a target texture: none for a camera that draws to the screen, a RenderTexture for a camera whose picture is used elsewhere (a minimap, a mirror). Sourced · Unity manual Whether a renderer is seen by the player depends on whether any screen camera draws its layer. Sourced · Unity manual

A renderer on a layer that no screen camera’s mask draws is not seen by the player. Sourced · Unity manual

Layer names

Layer names are in the TagManager of globalgamemanagers; layers 0 to 7 are built in (Default, TransparentFX, Ignore Raycast, Water at 4, UI at 5). The layers each game names:

Game	Named layers	Confidence
SkateBIRD	8 Wheels, 9 Board, 10 Ragdoll, 11 Ghost, 12 Ghost Listener, 13 Clothing Collisions, 14 See-thru Skatables, 15 Skate Zones, 16 Board-Interactive Deco, 17 Room Boundary Mesh, 28 Mini Map Markers, 29 Collectibles, 30 Collectible Toucher, 31 Post-Processing	Proven · SkateBIRD
Sledding Game	6 Default_HardCameraBlock, 7 Sled, 8 Player, 9 Ragdoll, 10 Terrain, 11 UI World, 12 PlayerHitCollider, 13 OnlyCollideWithPlayer, 14 Interactable, 15 DefaultNoCollideWithRagdoll, 16 AudioCutoffBlocker, 17 BarrierForPlayer, 19 BillboardCamera	Proven · Sledding
PEAK 3.0.0	8 DontCollideWithCharacter, 9 OnlyCollideWithCharacter, 10 Character, 11 GhostCharacter, 12 MIrror, 14 Hazard, 15 Rope, 20 Terrain, 21 Map, 22 InvisWall, 25 Lighting, 27 MirrorHidden, 29 Vines, 30 SDF, 31 Post	Proven · PEAK

Other uses of layers

Layers also decide physics: the physics settings store a layer collision matrix, and a collider’s layer decides what it touches. Sledding Game and PEAK name layers for that purpose (OnlyCollideWithPlayer, DontCollideWithCharacter). Inferred

SkateBIRD’s Post-Processing layer (31) holds the post-processing volumes, see post-processing. Inferred · SkateBIRD

Layer collision matrices

The PhysicsManager in globalgamemanagers stores m_LayerCollisionMatrix: 32 words, word a having bit b set when layers a and b collide. Observed · SkateBIRD, Sledding, PEAK Read in each of the three installs the matrix is symmetric over all 32 × 32 pairs. Observed · SkateBIRD, Sledding, PEAK (No frame captures it: it is a CPU setting.)

Game	Layers that collide with nothing else or everything	Layers with notable exclusions	Confidence
SkateBIRD	Room Boundary Mesh (17) and Mini Map Markers (28) collide with every layer	Wheels, Board and Ragdoll collide with none of layers 8 to 13 (themselves, each other, Ghost, Ghost Listener, Clothing Collisions); Skate Zones (15) and Board-Interactive Deco (16) collide only with a few layers (each with 16 or 14 layers excluded); Default excludes 11, 12, 13, 15 and 16	Observed · SkateBIRD
Sledding Game	Default, Default_HardCameraBlock and Terrain collide with the same set	Sled does not collide with Player or Ragdoll; PlayerHitCollider collides only with layer 7 (Sled); OnlyCollideWithPlayer collides only with layer 8 (Player); DefaultNoCollideWithRagdoll is Default without Ragdoll; UI World, Interactable, AudioCutoffBlocker and BillboardCamera collide with no named layer, not even themselves	Observed · Sledding
PEAK	InvisWall and MirrorHidden exclude only layer 8; Vines and SDF only layers 8 and 9	Character does not collide with layers 8, 11, 12, 13, 14, 16 or 17; OnlyCollideWithCharacter collides with Character (10), Hazard (14) and a few unnamed layers; GhostCharacter collides with only layers 3, 6, 7, 13 to 24 and 26 to 30	Observed · PEAK

The full rows are in the install’s PhysicsManager; the table summarises them.

Culling masks in SkateBIRD

SkateBIRD’s Minimap/Mission Marker shader draws big spheres on ordinary MeshRenderers on layer 28 (Mini Map Markers). They are invisible in the game: the player’s Main Camera has the culling mask 0xe003ff17, which excludes layer 28, and only the Objective Map Camera (for escape menu), which renders to a texture, has 0xf003ff17, which adds layer 28. Proven · SkateBIRD

0xe003ff17 draws layers 0, 1, 2, 4, 8 to 17 and 29 to 31; 0xf003ff17 adds 28. Proven · SkateBIRD Every scene of the install has this arrangement or a simpler one: scenes 0 to 7, 12 and 13 have exactly the Main Camera (mask 0xe003ff17, depth −1, near 0.1, far 5000) and the Objective Map Camera (for escape menu) (mask 0xf003ff17, depth 0, near 0.3, far 1000, target texture object 1283 of the same file); the credits scene (6) adds a Credits Camera with mask 0xffffffff at depth 10 that draws every layer to the screen; the loading scene (8) has one Main Camera with every layer; scenes 9 to 11 have no camera. Proven · SkateBIRD The main camera’s field of view is 75° (40° in the title scene) and the map camera’s varies by scene (60° to 92.2°). Proven · SkateBIRD