Numalphatables (DEF)

numalphatables <value>

Defines the number of blend tables to be used by alpha.

The IDs for the alpha tables start from 1, because ID 0 is reserved to 33% transparency.

The transparency of the alpha tables should range from 0% to 50%. The second half will be generated by reversing the first half.

Valid values are powers of two, or powers of two minus one. The two variations apply slightly different calculations, with the latter being slightly more accurate and efficient in data storage. (TODO: Explain further and add the actual math formulas.)

For example, if you define numalphatables as 16, you should import table ids 1-16 using blendtable, and in-game there will be 32 steps of transparency. Ion Fury uses a value of 31 for 64 steps of transparency with the more accurate calculations.

A package for Duke Nukem 3D with blend tables generated in this ideal manner is available and permitted for use in projects with credit to the author: File:Duke3d blend package.7z

You can import up to 128 tables, which would provide a table for every value of alpha. However a value so high is probably not necessary, since the palette of a game won't have enough steps for a color to justify such a value. Additionally, such a large lookup table would overflow the caches of most CPUs, wrecking performance. It would be more reasonable to use a value similar to the shade table, which in Duke 3D case is 32, so a value of 16 for numalphatables would be more logical.