Placing 3d objects on a rotating/tilting map

Objects rotate around their own centre, so their own (0, 0, 0). To change this (on static objects), use PositionMesh/FitMesh. For animated objects, I believe a pivot it best. There is a routine in the archives: http://www.blitzbasic.com/codearcs/codearcs.php?code=732
or you could use this:

Function CenterMesh(mesh)

	a_minx# = 100000
	a_maxx# = -100000
	a_miny# = 100000
	a_maxy# = -100000
	a_minz# = 100000
	a_maxz# = -100000

	validmesh = (mesh <> 0)
	If validmesh Then validmesh = EntityClass$(mesh) = "Mesh"
	If validmesh Then
		For i = 1 To CountSurfaces(mesh)
			s = GetSurface(mesh, i)
			For v = 0 To CountVertices(s) - 1
				TFormPoint VertexX(s, v), VertexY(s, v), VertexZ(s, v), mesh, 0
				If TFormedX() < a_minx Then a_minx = TFormedX()
				If TFormedX() > a_maxx Then a_maxx = TFormedX()
				If TFormedY() < a_miny Then a_miny = TFormedY()
				If TFormedY() > a_maxy Then a_maxy = TFormedY()
				If TFormedZ() < a_minz Then a_minz = TFormedZ()
				If TFormedZ() > a_maxz Then a_maxz = TFormedZ()
			Next
		Next
	End If
	
	PositionMesh mesh, -(a_minx+a_maxx)/2, -(a_miny+a_maxy)/2, -(a_minz + a_maxz)/2
	
End Function