This is something I'm experimenting with:
public void mouseMoved(MouseEvent e) {
SimpleVector s = Interact2D.reproject2D3D(world.getCamera(), buffer, e.getX(), e.getY());
int[] i = Interact2D.pickPolygon(world.getVisibilityList(), s);
if(Interact2D.getObjectID(i)!= -1)
{
obj = world.getObject(Interact2D.getObjectID(i));
obj.setAdditionalColor(java.awt.Color.RED);
}
else if(obj != null) obj.clearAdditionalColor();
}