====== map_GetMipmapLevel ======

===== Description =====

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

===== Function prototype =====

<code>ZMAP CExtAPI::map_GetMipmapLevel(ZMAP hMap, long MipLevel);</code>

===== Arguments =====

^ Name ^ Type ^ Comment ^
| hMap | ZMAP | A handle to a map variable, a mipmap of which is to be retrieved. |
| MipLevel | long | The sub-sampling factor of the desired mipmap. See comments below. |

===== Return value =====

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. 

===== Comments =====


==== MipLevel =====

//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:

<code>
MipLevel = ResStep ^ n
</code>

Where:
  * //ResStep// is the resolution step (factor) between successive mipmap levels (see [[zeolite:functions:map_GetMipmapResStep]])
  * //n// is a positive integer.
  * //MipLevel// is smaller than or equal to //MaxLevel//, where //MaxLevel// is the maximum mipmap level (see [[zeolite:functions:map_GetMipmapMaxLevel]]).