XPLMProbeTerrainXYZ
XPLM_API XPLMProbeResult XPLMProbeTerrainXYZ(
XPLMProbeRef inProbe,
float inX,
float inY,
float inZ,
XPLMProbeInfo_t * outInfo);
Probes the terrain. Pass in the XYZ coordinate of the probe point, a probe object, and an XPLMProbeInfo_t struct that has its structSize member set properly. Other fields are filled in if we hit terrain, and a probe result is returned.