Entry 13

Animation: quaternion keys by channel, pinned to the original's matrix

2026-10-144mformatrenderdecomptest

Filescrates/rugrats-data/src/anim.rscrates/rugrats-render/src/models.rsmesh.rscrates/rugrats-render/tests/against_original.rscrates/rugrats-viewer/src/main.rs

A database's animations are three files. ANM indexes them (first frame, frame count; 0xffff none), FRM lists frames (a duration the loader multiplies by 5, and a range of keys), ROT holds the keys: two words packing a quaternion as four signed fields (14, 14, 14 and 13 bits) and a 5-bit channel, or, with bit 29 set, a lift that moves the object up or down. The hierarchy maps channels to parts through the bytes at its +0x14. This came from the two samplers, anim_set_frame (0x80055170) and anim_blend (0x800552bc), and UpdatePartRotations (0x8004a5dc, named by its own error message), which builds each part's matrix from its quaternion and its parent's.

rugrats-viewer 0 --anim 1,239 poses DB00's Tommy at each of the 50 key frames of animation 239, a walk. The first convention tried was the textbook one; Tommy walked convincingly with it, which is why it was not trusted. quaternion_matrices_match_the_original calls the original's quaternion-to-matrix (0x8001fc48) in rrt-emu on five quaternions and compares: the game's matrix is the transpose of the textbook's, and the port now uses it (all within 8/4096).

On the way: DB00A.RAW is 262144 bytes, not 294912, though load_rooms uploads 576 x 256 for every database; the port's VRAM load now stops where the data ends. And DB22's FRM and ROT are absent from the file table, so the opening cinematic must pose its characters from its stream, not from animations.