3DC reading: missing data

[culacant]

The 3DFX 3DC files contain a lot of data that we do currently not read in. The purpose of this data remains a mystery.

Example for CYRSA023.3DC:

  1 Usage for memory reader:
  2  (0 bytes)
  3  HEADER:    0x00000000 (64 bytes)
  4  FACEDAT:   0x00000040 (16278 bytes)
  5  FVERDAT:   0x00003FD6 (1548 bytes)
  6  VERTDAT:   0x000045E2 (1548 bytes)
  7  NORMDAT:   0x00004BEE (5652 bytes)
  8  FRAMEDAT:  0x00006202 (208 bytes)
  9  FVERDAT:   0x000062D2 (1548 bytes)
 10  EMPTY:     0x000068DE (1884 bytes)
 11  FVERDAT:   0x0000703A (1548 bytes)
 12  EMPTY:     0x00007646 (1884 bytes)
 13  FVERDAT:   0x00007DA2 (1548 bytes)
 14  EMPTY:     0x000083AE (1884 bytes)
 15  FVERDAT:   0x00008B0A (1548 bytes)
 16  EMPTY:     0x00009116 (1884 bytes)
 17  FVERDAT:   0x00009872 (1548 bytes)
 18  EMPTY:     0x00009E7E (1884 bytes)
 19  FVERDAT:   0x0000A5DA (1548 bytes)
 20  EMPTY:     0x0000ABE6 (1884 bytes)
 21  FVERDAT:   0x0000B342 (1548 bytes)
 22  EMPTY:     0x0000B94E (1884 bytes)
 23  FVERDAT:   0x0000C0AA (1548 bytes)
 24  EMPTY:     0x0000C6B6 (1884 bytes)
 25  FVERDAT:   0x0000CE12 (1548 bytes)
 26  EMPTY:     0x0000D41E (1884 bytes)
 27  FVERDAT:   0x0000DB7A (1548 bytes)
 28  EMPTY:     0x0000E186 (1884 bytes)
 29  FVERDAT:   0x0000E8E2 (1548 bytes)
 30  EMPTY:     0x0000EEEE (1884 bytes)
 31  FVERDAT:   0x0000F64A (1548 bytes)
 32  EMPTY:     0x0000FC56 (1884 bytes)
 33  UKNDAT:    0x000103B2 (3096 bytes)

FVERDAT is the frame vertex data for the animations, these are vertex offsets per frame. It is always followed by a slightly larger EMPTY section, which is part of the missing data. No relations between EMPTY and any other data has been found yet.
We also have UKNDAT at the end, double the size of a single frame FVERDAT section. Also no idea what that does.

Maybe relevant to note: some non-humanoid models have their animations spaghettified, maybe caused by this missing data?