Terrain deferred decals

Terrain deferred decals project material information into terrain virtual-texture targets. Their output layout differs from the final scene G-buffer, even though both carry colour and normals. Observed · decal and terrain producer shaders

HoudiniDecalInstancerComponent embeds a StaticDDecalLibrary, a counted DDecalModel reference list and counted static-instancer items. Each item’s first model byte indexes that list on all 34,477 examined items. Instances are 100-byte projection-box records with world-space centres; applying the owning Entity transform again changes their positions incorrectly. Proven · model-index census Observed · world-space box comparison

Static deferred decal instance100 bytes76% known

ProvenObservedSourcedInferredUnknownNot described

0

1

2

3

4

5

6

7

8

9

A

B

C

D

E

F

0x0

stored identityu64

record classu32 = 0x295F035C

first half-axisfloat3

0x10

… first half-axis

stored bytesbytes

second half-axisfloat3

0x20

… second half-axis

fadef32

stored fieldsbytes

0x30

… stored fields

atlas U offsetf32

world centrefloat3

0x40

… world centre

atlas U widthf32

box minimumfloat3

0x50

… box minimum

box maximumfloat3

0x60

… box maximum

Offset	Size	Type	Field	Confidence	Notes
0x0	8	u64	stored identity	Unknown	0 in the measured records
0x8	4	u32 = 0x295F035C	record class	Observed
0xC	12	float3	first half-axis	Observed
0x18	4	bytes	stored bytes	Unknown	not interpreted
0x1C	12	float3	second half-axis	Observed
0x28	4	f32	fade	Observed
0x2C	12	bytes	stored fields	Unknown	not interpreted
0x38	4	f32	atlas U offset	Observed
0x3C	12	float3	world centre	Observed
0x48	4	f32	atlas U width	Observed
0x4C	12	float3	box minimum	Observed
0x58	12	float3	box maximum	Observed

The atlas interval is [offset,offset+width]. The GPU pack uses centre trunc((offset+width/2)*65535) and half-width trunc(width/2*65535), with opacity scaled by (1-fade)*modelOpacity. Observed · instance packer disassembly

DDecalModel bodies are 115 bytes in all 70 stored entries. Four references supply Diffuse, Normal, Height and Mask1 maps, followed by flags and parameters. Model opacity is the f32 at body 72. Proven · body size census Observed · field mapping

Terrain target	Meaning	Confidence
o0	Albedo	Observed · executed terrain decal path
o1	Normal	Observed · executed terrain decal path
o2.x	Terrain displacement from TerrainDisplacement parameters	Observed · program and parameter mapping
o2.y	Mask1 G	Observed
o2.z	Normal A, roughness	Observed
o3.x	Mask1 R	Observed

Alpha is Mask1.B*(1-fade)*AlphaScale, with discard below .4 in the examined terrain-family program. Fifty-three of 69 classified models use this family, drawn by three pixel programs; a model belongs to it when its body bytes 48 and 49, the fields 6FBE0FE4 and WriteGBufferRoughness, are both zero. All 5,490 USNAT instancers have ForTerrain enabled, CellMinSize 50 and CellMarge 5. Observed · model classification, instancer census and interpreted real-record execution

Their distribution is uneven: the CITYSCHOOL campus area holds no terrain-family decal instances, while Area 52 holds 2,861. Observed · two area censuses

Two Entities carry a StaticDDecalComponent instead, for example MAD_PRP_GraffitiSEAMONSTERS_Back_FrontRockRight_A_002. The class derives from DDecalComponent and Visual; its instance (0x4A483387) has a null mesh reference and embeds a StaticDDecalLibrary and StaticDDecalSettings. Observed · both bodies

How are all terrain decal permutations scheduled?

The examined outputs and stored projection data are established; the full runtime ordering and compositing of every decal permutation with VT updates is not. Unknown