GPL Track Creating - Images

Authored by the GPLEA

Images in GPL come in three forms: MIPs, which are simple multi-level images used for textures; SRBs, which are MIPs with width & height (metres) that always face the viewer- suitable for trees & people; and PBFs, which are the program cover images, not used on track.

MIPs

There are 6 types of MIP you can create, 3 each of 4bit (16colour) and 16bit (4096, 32768 or 65536 colour):

Type 0 - 4bit - no transparency allowed

Type 1 - 4bit - a single transparent colour is allowed

Type 2 - 4bit - any number of transparent colours are allowed

4bit MIP types have a palette, so each of the 16 colours can be any of 65536 different colours (GPL is a 16bit game):

Type 3 - 16bit - 65536 possible colours, with 5 bits of red and blue, 6 bits of green. No transparency allowed.

Type 4 - 16bit - 32768 possible colours, 5bits per colour, transparency allowed (on/off)

Type 5 - 16bit - 4096 possible colours, 4bits per colour, transparency allowed (16 levels)

Repeating Values

Each MIP has two flags that control whether or not the MIP will repeat. This means that you can have an advert repeating along a wall. If you do not set these flags, you may see strange stretching of the textures in GPL.

MipMan, WinMip, (PapyBMP ?)

These three programs will let you convert BMP files from any paint program into MIP format. They have different uses:

MipMan converts 16bit and 4bit (no transparency) MIPs only. It will probably crash if you try the other types!

WinMip converts .........

PapyBMP converts .......

Bugs

There are a few points you should take into consideration: MIPs & SRBs can only be the following sizes:

1x1, 1x2, 1x4, 1x8,

2x1, 2x2, 2x4, 2x8, 2x16,

4x1, 4x2, 4x4, 4x8, 4x16, 4x32,

8x1, 8x2, 8x4, 8x8, 8x16, 8x32, 8x64,

16x2, 16x4, 16x8, 16x16, 16x32, 16x64, 16x128

32x4, 32x8, 32x16, 32x32, 32x64, 32x128, 32x256

64x8, 64x16, 64x32, 64x64, 64x128, 64x256

128x16, 128x32, 128x64, 128x128, 128x256

256x32, 256x64, 256x128, 256x256

Other sizes might work, but not on all graphics cards ! Example: 256x127 worked on a Voodoo2, but not on a GeForce2...

If your track does not work in software rendering mode, then your MIPs/SRBs are probably the cause.

SRBs

SRBs are MIPs with a few extra numbers. These numbers control how the SRB is rendered. They are:

Width and Height of the MIP (easy numbers).

Size of the SRB in metres - this tells GPL how big to render the SRB - example: tree height.

Middle,Bottom of the MIP in pixels - this is the pivot-point of the SRB - the point it rotates about when you look at it.

To create an SRB from a MIP, use SrbMan. It will also create a .3DO file that references the SRB, so you can include it directly in your track.

PBFs

PBF images are used for the program covers, weekend screen and newspaper picture. They are:

page0.pbf - - w*h

page1.pbf - - w*h

page2.pbf - - w*h

page3.pbf - - w*h

page4.pbf - - w*h

page5.pbf - - w*h

event.pbf - - w*h

bwpic.pbf - newspaper picture - w*h

Transferred to the wiki: 30.04.2009