Duke Nukem II Palette Formats
There are two different palette formats used by Duke Nukem II.
16-Color Palette
| Format type | Palette |
|---|---|
| Hardware | VGA |
| Colour depth | 18-bit |
| Number of colours | 16 |
| Games |
The 16-color palette is the most common palette format. It can be found in:
- 16-color images
- individual palette files (*.PAL)
- the game's main executable (offsets are for the decompressed registered version executable):
- in-game palette at offset 0x1B068
- "The End ...until Duke 3-D" message (actor no. 175) palette at offset 0x1B098
The palette stores each entry's red, green and blue value (in that order) each as one byte value, resulting in a total size of 48 bytes. However, the color values are not standard 6-bit VGA values - they range from 0 to 68 (inclusive). This is because the game doesn't directly submit these values to the VGA hardware, but always in conjunction with a fade-in effect. During the fade, the game repeatedly adds the palette values to an accumulator buffer (of 16-bit values) over the course of 15 steps, and divides the accumulated values by 16 before sending the result to the hardware. Combined with a short delay after each step, this results in progressive brighter colors, until the fade-in stops.
Consequently, to convert the palette values to standard 6-bit VGA values, you can use this formula:
val6 = val*15 / 16
The following table lists all the palette values and the corresponding 8-bit values.
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | 0 | 0 | 4 | 8 | 12 | 16 | 20 | 24 | 28 | 32 | 36 | 40 | 44 | 48 | 52 | 56 |
| 16 | 60 | 60 | 65 | 69 | 73 | 77 | 81 | 85 | 89 | 93 | 97 | 101 | 105 | 109 | 113 | 117 |
| 32 | 121 | 121 | 125 | 130 | 134 | 138 | 142 | 146 | 150 | 154 | 158 | 162 | 166 | 170 | 174 | 178 |
| 48 | 182 | 182 | 186 | 190 | 195 | 199 | 203 | 207 | 211 | 215 | 219 | 223 | 227 | 231 | 235 | 239 |
| 64 | 243 | 243 | 247 | 251 | 255 |
It is possible to use palette values greater than 68, but that will result in color errors during fade-in and fade-out.
See VGA Palette for details on converting between 6-bit and 8-bit values.
256-Color Palette
| Format type | Palette |
|---|---|
| Hardware | VGA |
| Colour depth | 18-bit |
| Number of colours | 256 |
| Games |
"Real" VGA palettes are stored in:
- NUKEM2.F* (see Duke Nukem II Animation Format)
- LCR.MNI
These are 768-byte files in classic (6-bit) VGA Palette format.
Credits
This file format was reverse engineered by K1n9_Duk3. lethal-guitar added some additional information regarding conversion of the 6-bit palette entries. If you find this information helpful in a project you're working on, please give credit where credit is due. (A link back to this wiki would be nice too!)