Characters (ONCC, TRBS, TRCM)

A character class is an ONCC instance (instance files), 3,232 bytes: Konoko, the Strikers, the cops. For now OpenOni reads its body: the meshes, the bones and how they hang together. The rest (physics, combat, AI, sounds) comes with the character engine (step 5).

OpenOni reads bodies with src/body.c. tools/onibody.py is the reference reader; it exports a body posed by an animation frame as OBJ or a preview. Worked out from Oni.exe v1.0 and checked on all 29 classes of level 1, five bodies each.

The class

Offsets are from the instance data. The links the body needs:

Offset	Tag	What
0xc34	TRBS	The body set: five TRCM links, lowest detail first
0xc38	TRMA	A texture per body part
0xc80	TRAC	The animation collection
0xc84	TRSC	The aiming screens

The class also links TXMP (0x20), ONCV (0x42c), ONCP (0x430), ONIA (0x434), CBPM (0xc3c) and CBPI (0xc40).

The AI's senses, read by its sight check (0x49adf0) and its memory (0x49b3f0, 0x499e80):

Offset	What	Level 1's thugs
0x120	Flags: bit 0, never startled	0xa
0x3f4	Central sight distance	475
0x3f8	Peripheral sight distance	150
0x3fc	Vertical sight, a cosine from straight up or down	0.766
0x400, 0x404	Central sight: cosines of full range and of none	0.819, 0.574
0x408, 0x40c	Peripheral sight: the same	0.174, −0.423
0x410, 0x414, 0x418	How long a contact of strength 4, 3, 2 lasts, in ticks	180, 900, 3600

The body (TRCM)

Offset	What
0x04	Bones (u16), 19 on the CD
0x54	TRGA: a geometry (M3GM) per bone
0x58	TRTA: each bone's offset from its parent (x, y, z floats)
0x5c	TRIA: the hierarchy, 4 bytes per bone: parent, first child, next sibling, padding (0xde)

When the body is loaded (0x4285e0), its run-time fields at 0x48, 0x4c and 0x50 are set to the elements of those three arrays. TRGA, TRTA, TRIA and TRMA have their u16 count at 0x16 and their elements from 0x18.

Each bone's geometry is in the bone's own space. In the rest pose (no rotations) the bones lie along a line.

Posing

iBuildMatriciesRecursive 0x427570 builds a matrix per bone, from bone 0 with the character's matrix as its parent. It walks down the first children in a loop and recurses for the next siblings. Each bone's matrix is:

1. its parent's matrix
2. translated by the bone's offset, in the parent's space (0x434c90)
3. times the bone's rotation from the animation (MUrMatrixStack_Quaternion 0x434c00)

Matrices are 3×4, stored by columns, with the translation last. MUrQuatToMatrix 0x4338c0 writes the rotation's columns, scaling by 2/|q|². Its first column is (1 − 2(y² + z²), 2(xy − zw), 2(xz + yw)): the transpose of the usual matrix for (x, y, z, w).

Check

body_test builds every class's five bodies on level 1. It then poses Konoko's highest-detail body by KONOKOidle_spec3 at frame 37 and prints the matrices, as tools/onibody.py game level1 --matrices konoko_generic KONOKOidle_spec3 37 does (to 3 decimals).

--obj out/body konoko_generic KONOKOidle_spec3 37 exports that pose, and --png draws it.