Scenes and the object hierarchy

A scene (levelN) is a flat list of objects: GameObjects (class 1), each with a Transform (class 4, or a RectTransform, 224, for UI) and a list of components (renderers, colliders, lights, cameras, scripts). Parents and children are links between Transforms; the file has no nesting. Sourced · Unity manual A scene file stores its own GameObjects and components, not the meshes, materials and textures its renderers use: those are in the sharedassets files, referenced by file id and path id. Observed · SkateBIRD

Contents of real scenes

Scene	Objects	GameObject	Transform	MonoBehaviour	MeshRenderer	MeshCollider	BoxCollider	LODGroup	Confidence
SkateBIRD level1 (bedroom 1)	44,305	16,189	14,871	4,847	1,351	1,669	515	0	Observed · SkateBIRD
SkateBIRD level12 (playground)	86,103	32,277	31,256	8,186	2,655	4,133	1,338	0	Observed · SkateBIRD
Sledding Game level1 (the mountain), build 25351629	151,088	45,145	42,057	12,168	18,069	694	4,151	2,507	Observed · Sledding
PEAK 3.0.0 level4	623,157	184,286	181,348	47,571	71,447	15,658	7,098	12,596	Observed · PEAK
PEAK 3.0.0 level1	52,515	14,457	14,025	2,820	8,178	1,670	fewer than 60	1,947	Observed · PEAK

Each count is the number of objects of that class in the one file. SkateBIRD’s scenes hold no terrain, no LODGroup and no navmesh; Sledding Game’s holds terrains and tree prototypes (terrain). Observed · SkateBIRD, Sledding

SkateBIRD’s scene roots show how a game scene is built: every playable scene is self-contained, with the player bird, the skateboard, cameras, post-processing, a dialogue manager and the mission set in it, so a scene is a whole level and not geometry alone. The playground (level12) has 18 roots including Level Elements, Missions - Playground, Non-Static Level Elements, Reset Positions, Player Birb, Cinemachine SkateCam 2.0, Skateboard For Skating and Main Camera. Observed · SkateBIRD

The frame

Unity’s frame is left-handed, +Y up, +Z forward, in metres. A yaw of 0 faces +Z. A renderer in a right-handed frame with counter-clockwise front faces (glTF) is reached by negating one axis (z): positions, normals and tangent directions negate z, triangle winding reverses, and a tangent’s w flips because the mirror flips the bitangent cross(normal, tangent.xyz) * w. Observed[every vertex and triangle of a sample of small real meshes, against an independent decoder]{games=“sledding”}

A Transform stores a local position, rotation (a quaternion x, y, z, w) and scale; the world matrix is the product of the chain from the root, Matrix4x4.TRS(position, rotation, scale) at each step. Sourced · Unity manual The product of such steps is not always a rotation and a scale: a rotated child under a parent with a non-uniform scale is sheared, and an odd number of negative scale components mirrors it. Inferred In Sledding Game’s first level 6 composed world matrices are mirrored and 1,224 are sheared, so they cannot be written back as one position, rotation and scale. Observed · Sledding A RectTransform’s stored local x and y can be stale: they come from its anchors: the parent rectangle’s minimum plus its size times the anchors interpolated at the pivot, plus the anchored position. Observed · Sledding

Prefabs

A prefab instance placed in a scene is not recorded as such in a build: the scene file holds its GameObjects, Transforms and components like any others, and no PrefabInstance object (class 1001) occurs in the SkateBIRD playground or its sharedassets0, Sledding Game’s mountain or sharedassets1, PEAK’s island scene or Big Walk’s world scene. Observed A prefab that something refers to by object, such as a terrain tree prototype, is a hierarchy of objects in an assets file with a root GameObject. Observed · Sledding The scene therefore does not say which prefab an object came from; repeated structure shows as repeated names (Generated_Rail_Node*, Combined Mesh (root: scene) N). Inferred

Inactive state

A GameObject can be stored inactive and a component stored disabled. Unity draws or uses an object only when none of the GameObjects on its Transform chain is inactive and the component is enabled; a file stores both flags as data, so a reader sees every renderer, collider and light whatever its state. Observed

A LODGroup lists, per level, the renderers it switches between; which level draws is Unity’s choice by screen size, not a scene fact. A disabled LODGroup switches nothing off: its levels draw together. Observed · Sledding, PEAK In Sledding Game, a LODGroup whose levels are one renderer each and whose coarser levels sit at the first level’s world matrix (up to rounding of a few f32 steps) is a mesh with a chain of coarser forms. Observed · Sledding

Static batching

A static-batched renderer draws a slice of a combined mesh whose vertices are already in world space; the renderer’s matrix is the identity, and the slice is a first submesh and a count. SkateBIRD’s level meshes are such combined meshes (Combined Mesh (root: scene) N) and ProBuilder output (pb_Mesh<number>). Observed · SkateBIRD

Materials and submeshes

Material i of a renderer draws submesh i. Submeshes beyond the renderer’s materials are not drawn, and materials beyond the submeshes draw the last submesh again as an extra pass. Sourced · Unity manual

Shadows

A renderer’s shadow casting mode is off, on, two-sided or shadows-only; m_ReceiveShadows is a separate flag. Observed Whether a draw receives shadows decides one of its shader keywords, see draw keywords. Observed

Build settings and scene identity

The scene list in globalgamemanagers gives each scene’s path in the editor project and its build index; levelN is scene N. Proven · SkateBIRD A scene’s root names can be stale copies from the scene it was cloned from, so identity comes from the list. Observed · SkateBIRD