|\
 | \
 |  \
b|   \
 |    \
 |     \
 |    a \
 +-------+
     d

native GetTerrainCliffLevel takes real x, real y returns integer

location get_terrain_z_loc = Location(0.0,0.0)

real GetTerrainZ(real x, real y) {
    MoveLocation(get_terrain_z_loc,x,y)
    return GetLocationZ(get_terrain_z_loc)
}

//...
высота = GetTerrainZ(GetCameraTargetPositionX(...),GetCameraTargetPositionY(...)) + GetCameraTargetPositionZ(...)
//...