zmap_GetMipmapLevel

Get a mipmap (as a ZMAP handle) for a given map.

ZMAP zmap_GetMipmapLevel(ZMAP hMap, long MipLevel);

A null pointer if the desired mipmap does not exist, or if an error occurred. Otherwise, a non-null handle to a map variable is returned.

MipLevel is the ratio of the side-lengths of the full-resolution map (referenced by hMap) to the side-lengths of the desired mipmap. So, for example, if you want to retrieve the mipmap that is one-quarter of the resolution of the full-res map, enter a MipLevel if 4.

Note, however, that not all values of MipLevel are allowed. Allowed values are given by:

MipLevel = ResStep ^ n

Where:

• ResStep is the resolution step (factor) between successive mipmap levels (see zmap_GetMipmapResStep)
• n is a positive integer.
• MipLevel is smaller than or equal to MaxLevel, where MaxLevel is the maximum mipmap level (see zmap_GetMipmapMaxLevel).