Picking - Interactive Web-Based Virtual Reality with Java 3D - page 211

Figure 24. Second code segment for PickBoundsBehavior.java

1. case MouseEvent.MOUSE_CLICKED:

2.

3. // getting the mouse position on the 2D viewing plane

4. x_m = ((MouseEvent)event[i]).getX(); y_m = ((MouseEvent)event[i]).getY();

5.

6. // transforming the 2D local coordinates to virtual world coordinates

7. canvas.getPixelLocationInImagePlate( x_m, y_m, pt_m );

8. canvas.getImagePlateToVworld( trans );

9. trans.transform( pt_m );

10.
11. // getting the direction for the picking shape
12. canvas.getCenterEyeInImagePlate( start_pt );
13. trans.transform( start_pt );
14. pt_m.sub( start_pt );
15. dirn.set( pt_m );
16. dirn.normalize();
17. dirn.scale( 2.5 );
18. end_pt.add( start_pt, dirn );
19.
20. BoundingSphere bounding = new BoundingSphere ( end_pt, 0.5 );

21. picktool.setShapeBounds( bounding, start_pt );
22.
23. result = picktool.pickAllSorted();
24.
25. if( result != null )
26. {
27. Primitive[] picked_node = new Primitive[result.length];

28. for ( int j=0; j < result.length && result[j] != null; j++ )

29. {

30. picked_node[j] = (Primitive)result[j].getNode( PickResult.PRIMITIVE );

31. current_attr = picked_node[j].getAppearance().getColoringAttributes();

32. current_attr.getColor( current_clr );

33. if ( current_clr.equals( yellow ) ) current_attr.setColor( red );

34. else current_attr.setColor( yellow );

35. }

36. }

37.
38. break;

obtain the corresponding 3D coordinate in the same way as other examples in previous
sections, and a spherical bound with a certain radius is specified to pick up objects within
the sphere. The color attributes of the objects picked are then changed.