NOTE: This is just for those curious to find corrections to the DMA docs.

The latest pre-release test versions of GTACARS are available here. (Possibly lacking in functionality, documentation, etc.)

It is quite difficult to use the palettes from the G24 file. The docs are missing quite a bit of information. Here are my thoughts, I will complete them as time permits...

(This will should be included in GTA Hacking Handbook)

Corrections and Notes regarding DMA's GTA technical doument [cds.doc v12.10]

3.1.3
Door_info_struct (Player position to enter)

typedef struct {
   Int16 rpy, rpx; // Y is first!  X&Y are measured from the exact CENTER of the car.
   Int16 object   //unused
   Int16 delta  // unused (sadly the "second" door on many cars will never function)
} door_info_struct;

Excluded Vehicle Types:
9 - Tram
13 - Boat
14 - Tank


3.2.1

About the Char *ptr fields in sprite_info_struct: They are said to be "empty in the file" and are not. In fact they are the only way to find the location of the sprites in the sprite_graphics data.
• 8bit: *ptr is a long offset to sprite in sprite_graphics pages
  Page number = ptr intDivide 65536
  Y position of the sprite in the page = Int((ptr Mod 65536) / 256)
  X position of the sprite in the page = (ptr Mod 65536) Mod 256
  
• 24bit: *ptr field is REPLACED with something like the following:
  
  Int ---- CLUT (to be reindexed by PalIndex)
  Byte ---- x offset in page
  Byte ---- y offset in page
  Int ---- page number in Sprite_Graphics
  

Jeff's notes:

• Sprites:
  GTA's transparent sprite color is not necessarily black! It is whatever color is used by palette index 0.
• Loading the deltas Pseudo-code

  loop each delta {
  
          fseek spriteGraphicsBegin + sprite.delta( ).ptr 
  
          fget size and length
  
          total_offset=0  
          loop delta( ).size {
                                  
                  total_offset+=offset
                  yo = (total_offset intDivide 256)
                  xo = (total_offset MOD 256)
  
                  loop x =  0 .. length-1 {
                          fget databyte
                          drawpixel xo + x,yo 
                  }
  
                  total_offset+=length    
  
          }
  }
  

• Loading and using the CLUT

  As for the G24 CLUT this is what I have to say...
  
  It is located in the file at the expected position by 3.8.1 (remember to
  add extra bytes to aux_block per 3.7)
  Imagine the clut in the first of the 64k pages is like this...
  
  CLUT    0                               1                               ...63
  color   B       G       R       0       B       G       R       0
  0       b0      g0      r0      0       b0      g0      r0      0
  1       b1      g1      r1      0       b1      g1      r1      0
  ...
  255     b255    g255    r255    0       b255    g255    r255    0
  
  
  To find the sprites CLUT you offset the sprite_info.clut and offset with
  (tile_clutsize / 1024).   Note: 1024 = 4*256 so tile_clutsize is RGB0 units.
  
  sprite.RealClut = palIndex(sprite.Clut + tileClutsOffset)
  
  

• Exactly how to use PalIndex to remap. - just an array of int16s, used to reindex the sprite.clut to a CLUT.
• How to convert all those relative numbered CarInfos to Absolute Sprite numbers... soon...
• much more...