source files: xgtm.[ch], term/*.trm, gtplot.h
(GT-GET-DEPTHCUEING-IS-ON) (SEND <gtm:terminal> :GET-DEPTHCUEING-IS-ON)
Returns NIL iff depthcueing is off.
When depthcueing is on, things far away are drawn darker than nearby things. This hack is primarily useful when displaying clouds of points or line segments, when normal surface-shading algorithms are useless.
Depthcueing mode is incompatible with normal shading on most machines, unavailable on many machines, and is basically a relic of times when only vectors or points could be rotated smoothly in real time.
Use of this switch is not particularly encouraged, but since it provides a useful service with no current substitute, it will probably not go away.