Method CameraPick:TVector(cam:TCamera,vx#,vy#)

   vy#=TGlobal.height-vy#

   Local px!
   Local py!
   Local pz!

        gluUnProject(vx#,vy#,0.0,cam.mod_mat!,cam.proj_mat!,cam.viewport,Varptr px!,Varptr py!,Varptr pz!)

   Local x#=Float(px!)
   Local y#=Float(py!)
   Local z#=-Float(pz!)
   
        gluUnProject(vx#,vy#,1.0,cam.mod_mat!,cam.proj_mat!,cam.viewport,Varptr px!,Varptr py!,Varptr pz!)

   Local x2#=Float(px!)
   Local y2#=Float(py!)
   Local z2#=-Float(pz!)

   _picked = Pick(x:Float, y:Float, z:Float, x2:Float, y2:Float, z2:Float)
   Return _picked
   
End Method
   
Method Pick:TVector(x:Float,y:Float,z:Float,x2:Float,y2:Float,z2:Float)
   
   Local source:TVector   = TVector.Create(x,y,z)
   Local dir:TVector      = TVector.Create(x2-x,y2-y,z2-z)
   Local distance:Double   = dir.Length()
   dir.Normalize()
      
   'Print "picking:"
   'Print "Distance="+distance
   'Print "Source: x="+Int(source.x)+" y="+Int(source.y)+" z="+Int(source.z)
   'now, we have a source, a direction and a distance
   'so we can walk along the line to find the first box.
   
   Local pos:TVector      
   Local i:Float
      
   For i=0 To distance Step 0.5 '0.5 for secure
      pos = source.Add(dir.Multiply(i))
      If _isBoxAt(pos.x, pos.y, pos.z) = True Then
         'Box found
         'Print "Box found"
         Return pos
      EndIf
   Next
   'No box found
   Return Null      
      
End Method