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 FCC0SSSS DDDDDDDD CCCCCCCC

HHHHHHHH GGGGGGGG FFFFFFFF EEEEEEEE

The contents represent the following:

AAAAAAAA

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

Scenery entry: mapping point 1 x

BBBBBBBB

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

Scenery entry: mapping 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: Mapping point 2 x

DDDDDDDD

 Scenery/model entry: Mapping point 2 y

F

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

CC

Colormode:

0 = translucent face

1 = additive face

2 = subtractive face

3 = standard face

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

TTTTTTTT

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

EEEEEEEE

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

Scenery/model entry: mapping point 3 x

FFFFFFFF

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

Scenery/model entry: mapping point 3 y

GGGGGGGG

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

HHHHHHHH

Scenery entry: mapping 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:

Texture information with LOD

Frame index (bin)	Loopmask (bin)	Step/played texture information (bin)
0000000	0000011	Starting offset + 00
0000001	0000011	Starting offset + 01
0000010	0000011	Starting offset + 10
0000011	0000011	Starting offset + 11
0000100	0000011	Starting offset + 00
0000101	0000011	Starting offset + 01
0000110	0000011	Starting offset + 10
0000111	0000011	Starting offset + 11
.........	.........	.........
.........	.........	.........
1111110	0000011	Starting offset + 10
1111111	0000011	Starting offset + 11

There is a great variety of loops to be made with this mechanism.

L

Leapflag: when set, this flag increases each 'step' created by the loopmask by factor 4 and increments by 1, 2 or 3 between the 4-step leaps according to standardized LOD-distances. This is particularly useful for animated textures with LOD.

000000000000

Unused?