Um, That would only work if you don't move the camera. try this:
(assuming terrain is the handle of your terrain)
(assuming terrain is the handle of your terrain)
;In the start of the program ,after creating the terrain: EntityPickMode terrain,2 ;In your editer's loop, do this to find the coordinates on the terrain the mouse is at: CameraPick camera,MouseX(),MouseY() ;Assuming camera is your camera's handle If PickedEntity()=terrain Then x#=PickedX#() y#=PickedY#() z#=PickedZ#() EndIf