[vtkusers] PointPicker Problem

[Chris Hood]

   I am trying to be able to click on certain actors and have the point 
where it was clicked returned. I only want the top point (from the current 
viewpoint). Sometimes it works and other times I get random points.

   When I use the GetPickedPositions command I get several coordinates, 
even when the spot is one where there should  be only one intersection. I 
use the first one and at some angles it is right, but at other angles the z 
coordinate is the negative value of what it should be. When I click on 
actors not on the pick list or in a some blank spots one or more points are 
returned.

   Using the GetPickPosition command I get a point that appear to be where 
the dataset is first intersected, even though there is no actor there. The 
GetPointId returns a point at the same coordinate.

   Does anyone know how to get the right coordinates returned? Also does 
anyone know how to make it only use the actors I tell it to use?


System info: WinXP, Java 1.4 with VTKPanel

Test Code:
    void Test(MouseEvent e) {
       int x=e.getX(), y=e.getY();
       pointPicker = new vtkPointPicker();
       pointPicker.AddPickList(actor3);
       pointPicker.AddPickList(actor0);
       pointPicker.AddPickList(actor2);
       pointPicker.PickFromListOn();
       pointPicker.Pick(x,y,0,renPanel.GetRenderer());

       int noOfPoints = pointPicker.GetPickedPositions().GetNumberOfPoints();
       System.out.println(noOfPoints);

       double[] a = pointPicker.GetPickPosition();
       System.out.println("PickPosition:   "  +a[0] + ",  " + a[1] + ",  " 
+ a[2]);

       System.out.println(pointPicker.GetPointId());
       a = modelData.GetPoint(pointPicker.GetPointId());
       System.out.println("Point Coord:   "  +a[0] + ",  " + a[1] + ",  " + 
a[2]);

       for(int i=0;i<noOfPoints;i++){
          a = pointPicker.GetPickedPositions().GetPoint(i);
          System.out.println("Point " + i +":   "  +a[0] + ",  " + a[1] + 
",  " + a[2]);
          }
       System.out.println("  ");System.out.println("  ");
       }


____________________________________
Chris Hood
Graduate Student Research Assistant
University of Colorado, Boulder
Space Environment Center - NOAA