Textureinformation Crash 2/3

Introduction
In Crash 2/3, texture information contains information about a 3D model's UV coordinates, (animated) textures and colorpalettes. The texture information can also be used by  'extended information'. Extended information can loop through multiple 12-byte structures to make animated textures, or provide settings for textures with different LOD's (Levels of Detail).

Texture information
Texture information information is stored in 12-byte structures in the 4th item of scenery and model entries. The format for the 12-byte structure consists of 3 consequent 32-bit integers and is as follows:

YYYYYYYY YYYYXXXX BBBBBBBB AAAAAAAA

TTTTTTTT FMM0SSSS DDDDDDDD CCCCCCCC

HHHHHHHH GGGGGGGG FFFFFFFF EEEEEEEE

The contents represent the following:

 AAAAAAAA 

Model entry: for triangle type “AA” and “BB”, UV point 3 x, for triangle type “CC”, UV point 1 x

Scenery entry: UV point 1 x

 BBBBBBBB 

Model entry: for triangle type “AA” and “BB”, UV point 3 y, for triangle type “CC”, UV point 1 y

Scenery entry: UV point 1 y

XXXX

CLUT-line origin x coordinate (CLUT: Color LookUp Table, contain the colors for a specific texture)

 YYYYYYYYYYYY 

CLUT-line origin y coordinate

The origin [x,y] for the CLUT-line is placed in a 16-bit interpretation of the texturechunk.

4-bit textures can have 2^4 = 16 different colors. Therefore the corresponding CLUT-line should always be 16 pixels long (in 16-bit!).

8-bit textures can have 2^8 = 256 different colors. Therefore the corresponding CLUT-line should always be 256 pixels long (in 16-bit!).

 CCCCCCCC 

Scenery/model entry: UV point 2 x

 DDDDDDDD 

Scenery/model entry: UV point 2 y

 F 

Flag determined to define a 8 or 4-bit texture. 0 = 4-bit, 1 = 8-bit.

 MM 

The colormode instructs how the texture should interpret the CLUT-colors (formatted as 'SBBBBBGGGGGRRRRR').  0 

Unused?

 SSSS 

Texturechunk segment index (0, 1, 2 or 3)

Each texturechunk in the original Crash games consists out of 4 segments.

The 16-bit size of a texturechunk is 256 x 128

The 8-bit size of a texturechunk is 512 x 128

The 4-bit size of a texturechunk is 1024 x 128

Therefore, the segments in 16-, 8- and 4-bit mode are respectively:

- 64 x 128,

- 128 x 128

- 256 x 128

The segment index refers to the origin of the segment. The UV points work relative from this origin. Note that the values of the UV points are not effected by 8- or 4-bit mode. The x,y values range from 0 to 255 and are fixed.

 TTTTTTTT 

Model entry: refers to an offset from 0x0C in the header, for which textureslot to use (0-7 (i.e. 0x0 – 0x40 ) )

Scenery entry: refers to an offset from 0x2C in the header, for which textureslot to use (0-7 (i.e. 0x0 – 0x40 ) )

 EEEEEEEE 

Model entry: for triangle type “AA” and “BB”, UV point 1 x, for triangle type “CC”, UV point 3 x

Scenery/model entry: UV point 3 x

 FFFFFFFF 

Model entry: for triangle type “AA” and “BB”, UV point 1 y, for triangle type “CC”, UV point  3 y

Scenery/model entry: UV point 3 y

 GGGGGGGG 

Scenery entry: UV point  4 y (applies to quads only)

 HHHHHHHH 

Scenery entry: UV point  4 x (applies to quads only)

Extended information
Extended information is in the 7th item in scenery entries and/or the 5th item in model entries. It is stored as 32-bit integers and can have 2 different formats according to flag 'F':

'''F???????? ???????? ?????OOO OOOOOOOO'''

OOOOOOOOOOO

Starting offset (in 12-byte structures) in the item for texture information. The first structure is indexed by 1, not 0. 0 is reserved for non-textured!

Texture information with LOD
If flag 'F' is set, the extended information will serve as texture information with 8 customizable LOD-settings according to camera distance, ranging from close (AA) to further away (II).

1AABBCCDDE EFFGGHHI I0000OOO OOOOOOOO

 AA, BB, CC, DD, EE, FF, GG, HH, II 

LOD-settings. Since each texture has a maximum of 4 LOD's (respectively from hi- to lo-res), each one of these 8 settings can be set from 00 (hi-res) to II (lo-res) in binary.

 0000 

Unused?

Animated texture information
If flag 'F' is not set, the extended information will serve as animated ''texture information. ''The LOD-distances are standardized. This extended information will define a 128-frame loop ranging from 0 to 127, starting at the starting offset.

00000000 0000MMMM MMMMLOOO OOOOOOOO

 MMMMMMMM 

Loopmask. Each frame in the 128-sized loop will be masked by this value. For example, a value of 0x3 would result in a subloop of 4 frames that is repeated 32 times within the 128 frame-sized loop: There is a great variety of loops to be made with this mechanism.

 L 

Leapflag: when set, this flag makes the offset refer to another 32-bit structure inside the 7th item in scenery and/or the 5th item in models. The eventual texture uses the offset of the structure that does not refer to another one, like a childnode relating to a leafnode.

 000000000000 

Unused?