ART/ART.CAR and ART/TRANS.TBL

Decoder: tools/car.py. Output: out/car/NNNN.png (RGBA), out/car/sheet.png (labelled contact sheet), out/car/index.json (per-sprite metadata), out/car/palette.png.

Summary

ART.CAR is a relocatable memory image of 3DO Cel Control Blocks (CCBs), carried over from the 3DO original. The PC port kept the 3DO CCB struct but:

• converted the pixel data to uncompressed 8-bit indexed pixels, row-major, stride = width;
• appended width/height fields to the CCB (68 bytes instead of 3DO's 60);
• reused PRE0 (3DO preamble word 0) as a PC draw-mode selector, and PRE1 as a parameter.

All multi-byte values are little-endian. The whole file is loaded into one GlobalAlloc block (size rounded up to 4, plus 0x4000 bytes of scratch space). Pointer fields hold file offsets and are rebased by adding the block address.

There are 2165 CCBs (1949 unique source rectangles; the rest are aliases that reuse the same pixels). There is no name table, so sprites are addressed by index (the code uses ccbBase + idx*0x44).

File layout

Offset	Size	Contents
0x00	16	Header
0x10	count*0x44 = 0x23F14	CCB array
0x23F24	count*8 = 0x43A8	Scale-shift table, one entry per CCB
0x282CC	0x400	Game palette, 256 x BGRx (same bytes as the PS480.RFA BMP palette)
0x286CC	0x404	Win32 LOGPALETTE (ver 0x300, 256 entries): the DirectDraw palette
0x28AD0	16	PLUT A (4-bit -> 8-bit remap), used by CCB 1969/1971
0x28AE0	16	PLUT B, used by CCB 1970/1972
0x28AF0	.. EOF	Pixel data, referenced by CCB.source

Header (0x10 bytes)

Off	Type	Value	Meaning
0	char[4]	CCBA	magic
4	u32	0x1D650F	file size. The loader rejects the file if this does not match; afterwards it is overwritten with the allocation size
8	u32	2165	CCB count
0xC	u32	0x23F24	offset of the shift table (rebased; global DAT_00440c58)

CCB (0x44 bytes)

Off	3DO name	Type	Notes
0x00	ccb_Flags	u32	3DO flags. Only these are used on PC: bit31 0x80000000 SKIP; bit30 0x40000000 LAST (end of list); 0x20 BGND (colour 0 is drawn opaque rather than transparent); 0x1000 means "corners are explicit" (see below). File values: 0x7FE64400 (1847) and 0x7FE64420 (318, the opaque tiles)
0x04	ccb_NextPtr	ptr	0 in the file; rebased if nonzero; draw-list link
0x08	ccb_SourcePtr	ptr	offset of the pixel data
0x0C	ccb_PLUTPtr	ptr	0x282CC (palette) for all but 4 CCBs; mode 0x11 remaps through a 16-byte PLUT
0x10	ccb_XPos	s32 16.16	screen X (0 in the file). With flag 0x1000 set, 0x10..0x2C instead hold 4 corner points (x,y) in 16.16
0x14	ccb_YPos	s32 16.16
0x18	ccb_HDX	s32 12.20	0x100000 = 1.0
0x1C	ccb_HDY	s32 12.20	0
0x20	ccb_VDX	s32 16.16	0
0x24	ccb_VDY	s32 16.16	0x10000 = 1.0
0x28	ccb_HDDX	s32	0
0x2C	ccb_HDDY	s32	0
0x30	ccb_PIXC	u32	3DO pixel-processor control word. Not read by the PC renderer; it is a leftover that correlates with PRE0 (0x1F001F00 normal, 0x1F009700 mode 1, 0x1F009B00 mode 2, 0x1F811F81 mode 3, 0x1F801F80 mode 5, 0xFFFFFFFF mode 0xD, 0x1F811F00 set to mode 0x10 at runtime)
0x34	ccb_PRE0	u32	PC draw mode (table below)
0x38	ccb_PRE1	u32	mode parameter (mode 0x10: 4 key colour bytes; mode 8/9: fill colour/level)
0x3C	ccb_Width	u32	pixels, also the source stride
0x40	ccb_Height	u32

Screen corners (Cel_ComputeCorners 0x4260A0) follow 3DO semantics: P0=(X,Y), P1=P0+HD*w, P2=P0+HD*w+VD*h (+HDD), P3=P0+VD*h. The HD values are 12.20 fixed point, which is why the code computes (HDX>>4)*w>>16. Cel_ComputeCorners2x (0x426180) is the pixel-doubled variant (DAT_0043fcf0, for 640x480 output). The textured-quad rasteriser is Cel_DrawQuad (0x410B9C, edge walk) calling Cel_TexSpanRows (0x4104D5).

Shift table (8 bytes per CCB)

{s32 wshift, s32 hshift} = log2(width), log2(height), or 0 if the dimension is not a power of 2 (verified for all 2165 CCBs). Cel_SetScale (0x4336C0) uses it to set HDX/VDY for a requested on-screen size: shift if the value is nonzero, otherwise divide. Obj_SetCel (0x4338C0) stores &shift[idx] next to its copied CCB.

Palettes

• 0x282CC: 256 x BGRx. This is the game palette, identical to the palette in the .RFA BMPs.
• 0x286CC: LOGPALETTE passed to CreatePalette (DAT_00481720, DAT_00481728). Entries 0-9 and 246-255 have flags=1 (PC_RESERVED) and RGB=0. They receive the Windows static colours at runtime. Entries 10-245 have flags=4 (PC_NOCOLLAPSE) and hold BGRx game colours 0-235 shifted by +10.
• Sprite pixel values index the LOGPALETTE / DirectDraw palette (the +10-shifted one), not the BGRx table. This was verified visually: water, sand, and grass tiles render correctly only with the LOGPALETTE. Normal, shadow, and blend sprites use only values 0 and 10-245. Values 1-24 occur only as levels/nibbles in mode-5 light masks and mode-0x11 4-bit PLUT cels. Values 246-255 never occur. In code, mode 10 does GetNearestPaletteIndex(bgrxPalette, rgb) + 10, which confirms the offset.
• Index 0 is transparent unless flag BGND (0x20) is set.

Draw modes (CCB.PRE0), dispatcher Cel_DrawList (0x4262F0)

Tables (TRANS.TBL) are indexed in DirectDraw-palette space. src is the sprite pixel, dst the framebuffer pixel. Pixels with src==0 are skipped unless noted.

PRE0	internal	Effect	# in file
0	0/1	copy; colour 0 transparent (internal 0) or opaque if BGND (internal 1)	2072
1	2	shadow: dst = darken[4][dst] (x27/32)	11
2	2	shadow: dst = darken[2][dst] (x29/32)	21
3,4	3	50% translucent: dst = blend[src][dst]	9
5	3	additive light mask: dst = brighten[src][dst] (the blend path with the brighten base, so src is a level 0-31; sprites 1778/2077 use values 0-24)	2
6	-	untextured polygon fill (corners from +0x10), FUN_0041124d	0
7 / 9	-	flat fill FUN_00411628 (colour 0 / PRE1 low byte)	0
8	-	FUN_0041176c, darken level from PRE1	0
10	-	flat fill with 3DO RGB555 from *(u16*)(PLUT+2), mapped to palette+10	0
0xB,0xF / 0xC / 0xE	-	other untextured primitives (FUN_004118ba, FUN_0040fe4f, FUN_0041100f)	0
0xD	-	span-list shadow mask Cel_DrawShadowSpans (0x411BA5): dst = darken[4][dst]	46
0x10	4	key-blend: src in {PRE1 bytes 0..3, 0x0B} -> blend[src][dst], else copy	0 (set at runtime)
0x11	5	remap: dst = PLUT[src] (PLUT from CCB+0xC)	4
0x12	6	remap and blend: dst = blend[PLUT[src]][dst]	0
0x13	0	like 0	0

Internal mode 7 (dst = table[src] without a transparency test) also exists in the span loop.

Mode 0xD shadow-span source encoding (46 sprites: 116,117,120,121,133,137,141,153,755,842,...)

This data is not w*h bytes:

s16 rowOffset[height]      // relative to SourcePtr; 0 = empty row
row data at SourcePtr+rowOffset:
  repeat { u8 x0; u8 x1; } until next x0 == 0   (the first pair is always read, so x0 may be 0 there)
  x0,x1 are in 1/256ths of the cel width: px = x*w/256, inclusive span.

Row sampling steps by (height<<16 - 1)/screenRows, so the mask is resolution independent. The decoder renders it as 50%-alpha black.

Runtime patches (Car_Load 0x4095F0)

• CCBs 524-578: PRE0=0x10, PRE1=0x7A7B7C7D (key colours 0x7D,0x7C,0x7B,0x7A plus 0x0B are translucent).
• CCBs 452-456: PRE0=0x10, PRE1=0x807C7A0A.
• CCBs 1981-1986: flags |= 0x70, SourcePtr = scratch buffer after the file (base+size rounded to 4), PRE0=6, PRE1=0, width=height=0x80. These are runtime-generated surfaces, so their on-disk pixels are meaningless.
• Plut_BuildFadeRamp (0x408F30) is called on (PLUT 1970, PLUT 1969) and (PLUT 1972, PLUT 1971), 16 entries each. It builds 17 remap tables that lerp in RGB from A to B in 1/16 steps (DAT_00440c5c, DAT_00440c60), and is used to animate the 4-bit remapped cels.
• DAT_00481730 = CCB 2141, DAT_00481744 = shift[2141] (a special cel used by the HUD/map code).
• DAT_00481620[256] is set to the identity remap.

ART/TRANS.TBL (81924 = 0x14004 bytes)

This file is a cache of colour-lookup tables, generated by the game itself (Pal_InitTransTables 0x4090C0) from the LOGPALETTE with GetNearestPaletteIndex. If the file is missing, has the wrong size, or byte 0 is not 1, the game regenerates it and writes it back.

Offset	Size	Global	Contents
0	4	-	byte0 = 1 (valid flag), rest 0
4	0x10000	DAT_0048172c	blend[a][b] (index a*256+b) = nearest((pal[a]+pal[b])/2)
0x10004	32x256	DAT_00481740	darken[k][c] = nearest(pal[c]*(31-k)/32), k=0..31. DAT_00481724 = k2, DAT_00481748 = k4
0x12004	32x256	DAT_0048173c	brighten[k][c] = nearest(min(255, pal[c]+3*(k+1))), k=0..31

These tables were verified bit-exact against a recomputation from the ART.CAR LOGPALETTE (nearest by RGB squared distance over all 256 entries). A reimplementation can regenerate them instead of shipping the file.

Content (index ranges, approximate)

• 0-111: 32x32 opaque terrain tiles (sea/beach transitions, sand, grass, road, concrete, bridges).
• 112-460: trees and palms, rubble, fences, bunkers and turrets, tank/jeep/ASV bodies, tread strips, and shadow masks (mode 0xD).
• 461-660: wheels, soldiers, helicopter parts/rotors (translucent key-blend), ships/boats with wakes.
• 655-830: tiny infantry animation frames and debris.
• 830-1080: buildings and structures (flag towers, bunkers, houses, walls, domes) with destroyed variants.
• 1080-1790: explosions, fire, smoke, splashes, water rings, dust (effects animations).
• 1790-1900: team flags (animated, two colours), flag poles.
• 1940-1990: HUD/dashboard panels, radar, pulsing shots (1947-1963), 4-bit PLUT cels (1969-1972).
• 2000-2090: ripples/wake frames, dirt/grass/sky strips (2080-2089), map frame (2090).
• 2091-2124: vehicle side views and icons (selection screen: tank, APC, jeep, helicopter), small icons.
• 2125-2139: skull-with-helmet portraits (two team colours). 2140: digit table font. 2141-2164: small digits/icons.

Ghidra names (renamed in project returnfire)

Car_Load 0x4095F0, Car_Relocate 0x409560, Pal_InitTransTables 0x4090C0, Pal_FreeTransTables 0x409060, Plut_BuildFadeRamp 0x408F30, Cel_DrawList 0x4262F0, Cel_ComputeCorners 0x4260A0, Cel_ComputeCorners2x 0x426180, Cel_ExplicitCornersToScreen 0x426260, Cel_SetQuadCorners 0x426C10, Cel_DrawQuad 0x410B9C, Cel_TexSpanRows 0x4104D5, Cel_DrawShadowSpans 0x411BA5, Cel_SetScale 0x4336C0, Cel_AddToList 0x401220 (copies a CCB into the per-frame list and clears LAST), Cel_FlushList 0x433730, Obj_SetCel 0x4338C0. Filenames: s_Art_art_CAR_00440c90, s_Art_Trans_tbl_00440c9c. DAT_00481738 overrides the CAR path.

Open questions

• Semantic names for individual sprite indices. These are hard-coded in game code as idx*0x44 offsets; xref-mining can map them.
• Exact behaviour of the unused untextured modes (6-0xC, 0xE, 0xF) was not traced in depth.
• Whether the .RFA BMPs are blitted with +10 index translation was not checked (see the RFA docs).