Hi
Bruno,
I've
been working on a geometry editing program for a while now, and part of it
includes simple point picking. You have to do a bit of work to set it
up. You have to set the picking capabilities of the geometries you want
to be able to pick. Also, you have to enable pick reporting for any
nodes you want to be able to recover from a pick operation. What happens
is that the mouse event is used to generate a pick shape - usually a ray that
goes "into" the canvas. All shapes that intersect this ray are returned
in the pickResult. This pickResult is then used to get a
pickIntersection, which gives the coordinates and other information. The
coordinates returned are not screen coordinates as returned by the mouseEvent,
but instead virtual world coordinates from within your
Canvas3D.
Here
is a code segment from my program. My program also recovers the
transform3D and shape for the point, but I have removed that code for
simplicity. This method is called from processStimulus, and the class
extends Behavior. If you are using an indexed geometry, you first have
to get the pickIntersection (pi) object, then you can use either
pi.getClosestVertexCoordinates() to get the (x,y,z) coordinates directly, or
you can use pi.getClosestVertexIndex(). Note that
getClosestVertexIndex() returns the index of that vertex in the selected
primitive - in an IndexedQuadArray it returns a number from 0 to 3. To
get the real index in your geometry, see the final line of this
sample.
Good
luck. Picking can be annoying, but when it works, it's
great!
Chris
Oceanic Consulting Corporation
private void processPickPoint
(AWTEvent event) {
// set the pick
location to the location of the
click
if (event instanceof
MouseEvent)
pickCanvas.setShapeLocation((MouseEvent)event);
else
return;
Point3d eyePos = pickCanvas.getStartPosition
();
pickResult =
pickCanvas.pickAllSorted();
if
(pickResult != null)
{
// Get
closest intersection
results
PickIntersection pi =
pickResult[0].getClosestIntersection(eyePos);
// Position selected point at closest vertex
Point3d clickPt =
pi.getClosestVertexCoordinates();
pointArray.setCoordinate(0,clickPt);
pointArray.setValidVertexCount(1);
// set index of selection in this indexed quad
array
pointIndex =
pi.getPrimitiveCoordinateIndices()[pi.getClosestVertexIndex()];
}
}
Hello.
I�m sorry for the "desperate" subject but i�m
loosing my mind with this problem...
What i�m trying to do is to find out the (x,y,z)
of a point when i click a mouse button
Finding out x and y is easy with the MouseEvent
class.My problem is knowing the z value!
If the mouse is clicked on top of an object
that�s has z=10 in that point how can i find out this value?
All help is appreciated....
Thank you and keep up the good work
Bruno
Caiado
