An icon bitmap file can have any number of individual icons, which are lined up side-by-side in the file. If you are creating icon bitmap files, these files must meet the following requirements:
Icon bitmap files must be .bmp files.
The icon bitmap files are actually groups of files. For each icon bitmap file group there needs to be at least two image files: one containing 16x15 pixel images ending in _16i.bmp, and another containing 24x24 pixel images ending in _24i.bmp. For example, these files would be myicons_16i.bmp and myicons_24i.bmp.
All icon images in an icon bitmap file must be the same size, as defined by the file name suffix.
Each icon bitmap file group must contain similar icon images in the same order. This allows a single index to locate the desired bitmap, independent of which button size option the user has chosen.
If monochrome, Windows-compatible masks are available, they need to be stored in files ending in _16m.bmp and _24m.bmp. For example, these files would be myicons_16m.bmp and myicons_24m.bmp.
If 8-bit alpha channel data is available, it needs to be stored in _XXa.bmp files if the alpha is not premultiplied, and in _XXp.bmp files if the alpha is premultiplied, where XX is either 16 or 24. For example, these files would be myicons_16a.bmp and myicons_24a.bmp.
If the mask channel bitmap files are present, they are used. If the mask channel bitmap files are not present, then the alpha channel bitmap files are used. If neither the mask nor alpha channel data bitmap files are present, then the color of the upper-left pixel is deemed the transparent color, and a mask is generated automatically for the image bitmaps.
If you wish to generate icons via calls to render() in MAXScript, make sure you use the naming conventions previously described and place the .bmp files in the current 3ds max user-interface directory. You can get the current user-interface directory path with the function:
local ui_dir = cui.getDir ()