The IDTA or model data contained within a POLYMODEL structure totally represents the actual model of an object in Descent. The IDTA structures are present in *.POF files (Descent 1 Full Version V1.0), *.PIG files (Descent 1 Full Version V1.4+), *.HAM/*.HXM files (Descent 2 Full Version) and *.POL files (Descent Manager HAXMEDIT element files). The format is similar to Descent 3's and FreeSpace 1-2's IDTA information.

This document is a compilation of info discovered by myself (Mike Menefee), Peer Somerlund, Garry Knudson, and Bryan Aamot.

*.POF specs - Descent 1 3D model data files with this IDTA data embedded
*.HAM/*.HXM specs - Descent 2 3D model data files with this IDTA data embedded
HMEL specs (*.POL) - Descent Manager HAXMEDIT 3D model data files with this IDTA data embedded
IDTA specs - FreeSpace 1/2 IDTA specs
OOF specs - Descent 3 IDTA specs
eMail author: Mike Menefee

The first byte defines the block now following (0-5, see below). After a block the following byte defines the data of the next block, etc.

• 0 - EOF - Means end of tree reached
  

  + 0 short id = 0

• 1 - DEFPOINTS - Defines the vertices
  

  + 0 short id = 1 + 2 short n_Points + 4 VMS_VECTOR points[n_Points]

• 2 - FLATPOLY - Flat (non-textured) polygon
  

  + 0 short id = 2 + 2 short n_Points + 4 VMS_VECTOR vmsVector +16 VMS_VECTOR vmsNormal +28 short colorMap +30 short ptldx[n_Points] +.. if (!n_Points & 1)      short pad //Present only if n_Points is even

• 3 - TMAPPOLY - Textured polygons
  

  + 0 short id = 3 + 2 short n_Points + 4 VMS_VECTOR vmsVector +16 VMS_VECTOR vmsNormal +28 short texture +30 short ptldx[n_Points] +.. if (!n_Points & 1)      short pad //Present only if n_Points is even +.. UVL_VECTOR uvlVector[n_Points] //Controls Texture Mapping }

• 4 - SORTNORM - Sortnorms are planes that split the model recursively
  

  + 0 short id = 4 + 0 short id = 3 + 2 short n_Points + 4 VMS_VECTOR vmsVector +16 VMS_VECTOR vmsNormal +28 short zFront +30 short zBack

• 5 - RODBM - Never used.
  

  + 0 short id = 5 + 2 short bmpNum + 4 VMS_VECTOR vmsTopPoint +16 int BotWidth +20 VMS_VECTOR vmsBottomPoint +32 int TopWidth

• 6 - SUBCALL - Calls a subobject.
  

  + 0 short id = 6 + 2 short sobjNum + 4 VMS_VECTOR vmsStartPoint +16 short offset +18 int pad

• 7 - DEFP_START - Just a list of all points of the model with subobject assignment.
  

  + 0 short id = 7 + 2 short n_Points + 4 short formerPts //=0 in main model, !=0 in submodels + 6 short pad + 8 VMS_VECTOR vmsPts[n_Points]

• 8 - GLOW - Present only in player ship, always precedes polygon object.
  

  + 0 short id = 8 + 2 short glowVal

Note: The "color map" data type is an unsigned16 bit integer that represents a 5 bit, 256 color scheme. So, to get it out, you have to use a six bit mask, like this: