[vtkusers] Picking Points with Java

[Richard Haney]

Hello,

I am trying to create a simple visualizer using VTK with Java bindings and 
have a quick question I hope someone out there has an answer to.

I am trying to "pick" a point in the vtkPanel.Renderer object after 
displaying them on the current vtkPanel. I can do this with no problem, 
however there are a couple of issues:

1. The point labels displayed by the panel appear backwards in location 
(e.g., given point 0 is at the top-left of a generated square mesh and 5 is 
at the botom-left - if you select point 0 with the mouse the ID of 5 is 
shown)

2. Whenever you move the displayed actor with them mouse, the points stay 
constant but if you select it with a mouse click they are usually very off.

Attached is a sample copy of the code:
...
// Called initially to set the point labels:
public void addPointLabels() {
    this.PIDs = new vtkIdFilter();
     // Where this.reader is an vtkXMLUnstructuredGridReader
    this.PIDs.SetInput(this.reader.GetOutput());
    this.PIDs.PointIdsOn();
    this.PIDs.FieldDataOn();
    this.dm = new vtkLabeledDataMapper();
    this.dm.SetInput(this.PIDs.GetOutput());
    this.dm.SetLabelFormat("%g");
    this.dm.SetLabelModeToLabelIds();
    this.pointLabels = new vtkActor2D();
    this.pointLabels.SetMapper(this.dm);
    // Where this.renWin is a vtkPanel
    // Add the "Label" Actor to the renderer:
    this.renWin.GetRenderer().AddActor(this.pointLabels);
    // Re-Draw Panel:
    this.renWin.Render();
  }//End of addPointLabels()
...

// Called everytime the MouseClicked event is fired
// X is given value MouseEvent e.getX(), and
// Y is given value MouseEvent e.getY()
public synchronized void picked(int X, int Y) {
  // To select an ACTOR from the vtkPanel:
  vtkPointPicker picker = new vtkPointPicker();
  // Add this actor to the list:
  picker.AddPickList(this.actor);
  picker.PickFromListOn();
  // Where this.renWin is the vtkPanel object defined in this class
  picker.Pick(X, Y, 0, this.renWin.GetRenderer());
  if (picker.GetPointId() != -1) {
	System.out.println("You Selected the Point: " + picker.GetPointId());
  }else {
	System.out.println("You did NOT select a Point!");
  }
}// End of picked()

The above code doesn't generate any errors, just the strange output I 
described.

Whoever can solve this is truly a Java-VTK expert and has my thanks. I can't 
seem to find much info about Java-VTK issues.

Thank you.