It looks like you spent some time on this response, I really
appreciate that. As I mentioned in my first mail, depth, _visible and
_alpha are the properties I'm checking right now to resolve conflicts.
So my code looks very similar to your code below. This works
sometimes, but I've run into cases where there are 2 movieclips for
which hitTest() is true, _visible is true, _alpha is 100, and the
depths are identical. One of the movieclips is obscured behind the
other; there must be some way to distinguish them. Are there any
other properties on movieclips (maybe hidden ones) that might be of
use? The Flash runtime must be doing this internally for onRollOver
event firing; anyone know how this works?
Thanks,
Vishal
On 2/7/07, Karina Steffens <[EMAIL PROTECTED]> wrote:
Ok, I see your problem, so lets think what else you can do with the hitTest
approach...
First of all, you can set the shape flag to true, so that the hit test will
only return true if there's something there (as opposed to the entire
bounding rect).
Then you can test for _alpha (you might want to test for _visible also),
thus eliminating invisible buttons, such as your big rectangle that obscures
the rest.
Finally, checking for different depths - I recently discovered that if you
loop through a clip, it starts at the highest depth, even on the same layer:
for (var i in _root) {
trace(i + " " +_root[i].getDepth());
}
$version
clip3 -16379
clip2 -16381
clip1 -16383
So now you know which one has the highest depth: clip3, which also comes
first in the loop.
At this point, you can break the loop. If you need to go deeper, you can
then recurse within that clip, and see if it has any child mcs, which one of
those scores the highest hitTest and if that one has any children - etc.
Here's some quick&dirty code:
for (var i in _root) {
trace(i + " " +_root[i].getDepth());
}
_root.onEnterFrame = function() {
for (var i in this) {
var clip = this[i];
if (!(clip instanceof MovieClip)) {
continue;
}
if (clip._alpha == 0 || clip._visible == 0) {
continue;
}
if (clip.hitTest(_root._xmouse, _root._ymouse, true)) {
trace(clip);
break;
}
}
};
On the timeline, I placed three circular clips overlapping eachother, so
that clip1 is at the lowest depth and clip3 at the highest. I made clip3
invisible by setting it's alpha to 0.
After moving my mouse over the clips, starting from the third, the trace
result was:
$version
clip3 -16379
clip2 -16381
clip1 -16383
_level0.clip2
_level0.clip2
_level0.clip2
_level0.clip2
_level0.clip2
_level0.clip2
_level0.clip2
_level0.clip1
_level0.clip1
_level0.clip1
Each time the trace picked out the highest visible part of a clip, thus
resolving any conflicts.
Hope this helps to point you in the right direction.
Karina
> -----Original Message-----
> From: Vishal Kapur [mailto:[EMAIL PROTECTED]
> Sent: 07 February 2007 20:29
> To: Flashcoders mailing list
> Subject: Re: [Flashcoders] determining which object is
> displayed at agivenpoint
>
> To respond to the recent activity on this thread:
> Erik, the core functionality that I need really does need to
> be comprehensive and fairly generic: so, given any 3rd party
> swf which I don't have a priori knowledge of, determine which
> object is currently underneath the mouse. It needs to work
> for any movieclip or TextField object. It's proprietary so I
> can't really disclose why I need it.
> You mention that implementing this would be process
> intensive: this is ok to start. The way I would like to
> tackle this problem is to get it working functionally, and
> worry about performance later.
>
> Karina, Jason, the approaches you are suggesting of looping
> through all the movieclips and calling hitTest() on each one
> is exactly what my first approach was (see my first email in
> this thread). The problem is that very often multiple
> movieclips will return hitTest()==true for a given mouse
> position (clips at different depths, clips obscuring others,
> etc). That's what I meant by "2 conflicting objects" in my
> first mail. I'm trying to find an algorithm to resolve conflicts.
>
> There is another approach which Erik mentioned, which is to
> define/override the onRollOver callback for every object that
> I care about, and set some variable that keeps track of the
> last object that invoked onRollOver. I have tried this
> before, and I ditched it because I couldn't find a way to get
> TextField objects to invoke an onRollOver callback (or to
> otherwise respond to a 'roll over' event).
> Any ideas on this?
>
> Thanks,
> Vishal
>
>
>
> On 2/7/07, Jason Boyd <[EMAIL PROTECTED]> wrote:
> > I've been following this thread and am just curious --
> everyone seems
> > to be assuming that looping through all clips and doing
> hitTest() is
> > inefficient, but presumably this is exactly what the Flash
> player is
> > doing with every mouse move. Is there some good reason to
> assume the
> > Flash player is doing this internally much more efficiently
> than the
> > function exposed through AS as hitTest()? Without a priori
> knowledge,
> > I'd recommend trying this, and if it doesnt turn out to
> noticeably slow anything, you're done.
> >
> >
> >
> > On 2/7/07, Karina Steffens <[EMAIL PROTECTED]> wrote:
> > >
> > > Hi Vishal,
> > >
> > > I apologise ahead if I'm being dense here, but nobody
> seems to have
> > > mentioned the obvious solution:
> > > Looping through the mcs in your third party flash movie
> and checking
> > > for hit-test with the mouse position.
> > >
> > > var hit_array:Array = [];
> > > for (var i:String in target_mc){
> > > var mc:MovieClip = target_mc[i];
> > > if (!mc instanceof MovieClip){
> > > //not a movie clip - ignore
> > > continue;
> > > }
> > > //Check for hit test
> > > if (target_mc[i].hitTest(_root._xmouse, _root._ymouse, true)
> > > hit_array.push(target_mc);
> > > }
> > > }
> > >
> > > At the end of it you have an array of all the movie clips that
> > > "scored" a hit test.
> > >
> > > This code is just off the top of my head, an thoroughly untested.
> > > Also Depending on the structure of your flash movie, you will
> > > probably want to delve deeper and test for a hit within
> each movie clip that you encounter.
> > > It's also not very efficient, especially if you have to do
> > > recursion, so I wouldn't recommend doing it too often. (don't use
> > > onMouseMove but rather an enterFrame event, an interval
> or some kind
> > > of once-off event - depending on your application).
> > >
> > > Alternatively, if you already know which objects should
> be tested,
> > > you can do this more efficiently by hard-coding them
> manually into
> > > an array and looping within the array to check for a hit
> test. Not
> > > pretty, but should work.
> > >
> > > And finally, something that occurred to me while writing
> this post,
> > > you could try temporarily switching off the _visible
> property of the
> > > overlapping clip just before checking for _droptarget - and then
> > > switching it on again.
> > > This might be the least processor-intensive way of doing this.
> > >
> > > Cheers,
> > > Karina
> > >
> > >
> > >
> > >
> > >
> > > > -----Original Message-----
> > > > From: Vishal Kapur [mailto:[EMAIL PROTECTED]
> > > > Sent: 07 February 2007 01:26
> > > > To: Flashcoders mailing list
> > > > Subject: Re: [Flashcoders] determining which object is
> displayed
> > > > at agivenpoint
> > > >
> > > > Ok, got it. Thanks for the suggestion. I tried this but it
> > > > doesn't work with the third-party flash movie I am looking at.
> > > > They have an movie clip with _alpha set to 0 that
> covers the stage
> > > > at a depth higher than all other visible elements.
> > > > As a result _droptarget is always set to that object.
> What I need
> > > > is something that takes into account visibility.
> > > >
> > > > Any other thoughts on this?
> > > >
> > > > -- Vishal
> > > >
> > > >
> > > > On 2/6/07, Mike Mountain <[EMAIL PROTECTED]> wrote:
> > > > > What he's saying is that _droptarget will tell you exactly
> > > > what is at
> > > > > the top under the users mouse - but in order to use it you
> > > > have to use
> > > > > startDrag to fool it in to working. Maybe you could drag an
> > > > invisible
> > > > > clip around or something.
> > > > >
> > > > > M
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: [EMAIL PROTECTED]
> > > > > > [mailto:[EMAIL PROTECTED]
> On Behalf
> > > > > > Of Vishal Kapur
> > > > > > Sent: 06 February 2007 16:03
> > > > > > To: Flashcoders mailing list
> > > > > > Subject: Re: [Flashcoders] determining which object is
> > > > displayed at
> > > > > > a givenpoint
> > > > > >
> > > > > > I don't understand what you're suggesting. The user is
> > > > not dragging
> > > > > > the movieclip.
> > > > > >
> > > > > > The idea is to write a function with a signature like:
> > > > > > function getObjectAtPoint(xmouse:Number,
> ymouse:Number):Object
> > > > >
> > > > >
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