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Posted to batik-users@xmlgraphics.apache.org by don undeen <do...@yahoo.com> on 2004/02/04 21:37:33 UTC
detecting shape collision?
Hello,
I apologize if this is more of an SVG question than a Batik question, but I think it overlaps, and you guys are so helpful and repsonsive....
Is there any way with batik/java/svg to detect if two svg shapes have "collided" or overlap? For example, if you have two circles of some radius, and you move them closer together, I'd like an alert to go up when the edges collide. Or perhaps I'd like to know if two lines overlap.
Is there a method to do this that doesn't involve explicitly calculating the areas covered by each of my shapes?
I'm guessing the answer is "no," but I'd sure like it to be "yes"!
thanks for everything,
Don Undeen
---------------------------------
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Re: detecting shape collision?
Posted by don undeen <do...@yahoo.com>.
Your right; I didn't originally specify that I was really interested in collision events.
Maybe sometime in the distant future I'll implement the collision-checking into Batik, but I hope someone get to it before me! :)
thanks for everything, Mr. Sahu
Bibek Sahu <sc...@dodds.net> wrote:
I don't believe it's in the spec for SVG, though I could be wrong; anybody
know otherwise? As near as I can tell, there is no code in either Batik
or in Java to do precise 2D collision-detection, or deliver events upon
that. You asked about checking two objects, not about recieving events on
an arbitrarily-large number of objects.
Given that collision events are not in the SVG spec, you could:
(1) use Java3D, which does have collision events. You would, of
course, have to write a bit of glue code for it...
(2) come up with a more practical implementation of the check.
There might even be a Java-based system out there which will fire
collision events when two Shape objects collide. I don't know of any, but
I'm no graphics expert; I'm sure the algorithms have been researched,
though. You could find/write an implementation of such an algorithm, then
write a custom bridge for Batik so you could access it. [of course, it'd
only work with Batik at that point...]
Good luck.
- Bibek
On Wed, 4 Feb 2004, don undeen wrote:
> So you're saying that while there isn't code in batik to see if to SVG shapes intersect, I can turn them into java.awt.Shapes, and use code like jPong.PongObject.collides(shape1, shape2) to see if they collide?
>
> that makes sense; I wonder if that will ulitimately be practical for my
> system, where I intend to to have LOTs of shapes moving around. For N
> objects, I have to do (n+(n-1)+(n-2)+...+2+1 (i forget, is that what
> they'd call "O(log(n))" ?) comparisons every iteration to see if there
> are any new intersections. I've been able trying to avoid loops like
> that where possible.
> What I really wanted to have was a way to register a "collisionEvent"
> with a shape, so that collisions are just "announced" when they occur.
> Would something like that ever be in the works for SVG?
>
>
> Bibek Sahu wrote:
>
> Howdy,
>
> On Wed, 4 Feb 2004, don undeen wrote:
>
> > Is there any way with batik/java/svg to detect if two svg shapes have
> > "collided" or overlap? For example, if you have two circles of some
> > radius, and you move them closer together, I'd like an alert to go up
> > when the edges collide. Or perhaps I'd like to know if two lines
> > overlap.
>
> In principle, in SVG, the SVGSVGElement methods 'getEnclosureList()',
> 'getIntersectionList()', 'checkEnclosure()', and 'checkIntersection()' might
> be useful (though I don't know if they'd be enough)... but in practice I
> don't think they're implemented in Batik yet (at least, that the impression
> I got from what I've seen on this list).
>
> In practice with Batik, you can get the GraphicsNode associated with an
> SVGElement, and then use GraphicsNode.getOutline() (or if it's a
> ShapeNode, use ShapeNode.getShape()) for both nodes, then check if the
> returned Shape objects intersect:
>
> BridgeContext bc = svgComponent.getUpdateManager().getBridgeContext();
>
> SVGElement circle1=...., circle2=....;
> GraphicsNode g1 = bc.getGraphicsNode(circle1);
> GraphicsNode g2 = bc.getGraphicsNode(circle2);
>
> Shape outline1 = g1.getGlobalTransform().createTransformedShape( g1.getOutline() );
> Shape outline2 = g2.getGlobalTransform().createTransformedShape( g2.getOutline() );
>
> if(outline1.intersects(outline2.getBounds2D()))
> // the first shape intersects the bounding-box of the second
> else
> // blah blah blah
>
>
> Note that it doesn't actually check if the two /shapes/ intersect, and
> especially with circles this could get to be a problem, but at least you now
> have Shape objects to work with. :-)
>
>
> If you need a method to see if two Shapes collide, Mr. Google is your
> friend. (e.g., http://www.risrani.com/programs/pong/doc-Pong/jPong/PongObject.htmlhttp://www.risrani.com/programs/pong/doc-Pong/jPong/PongObject.html
> ;-)
>
> Good luck!
> - Bibek
>
>
> > Is there a method to do this that doesn't involve explicitly calculating
> > the areas covered by each of my shapes?
> >
> > I'm guessing the answer is "no," but I'd sure like it to be "yes"!
> >
> >
> >
> > thanks for everything,
> >
> > Don Undeen
> >
> >
> >
> >
> > ---------------------------------
> > Do you Yahoo!?
> > Yahoo! SiteBuilder - Free web site building tool. Try it!
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: batik-users-unsubscribe@xml.apache.org
> For additional commands, e-mail: batik-users-help@xml.apache.org
>
>
> ---------------------------------
> Do you Yahoo!?
> Yahoo! SiteBuilder - Free web site building tool. Try it!
---------------------------------------------------------------------
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---------------------------------
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Re: detecting shape collision?
Posted by Bibek Sahu <sc...@dodds.net>.
I don't believe it's in the spec for SVG, though I could be wrong; anybody
know otherwise? As near as I can tell, there is no code in either Batik
or in Java to do precise 2D collision-detection, or deliver events upon
that. You asked about checking two objects, not about recieving events on
an arbitrarily-large number of objects.
Given that collision events are not in the SVG spec, you could:
(1) use Java3D, which does have collision events. You would, of
course, have to write a bit of glue code for it...
(2) come up with a more practical implementation of the check.
There might even be a Java-based system out there which will fire
collision events when two Shape objects collide. I don't know of any, but
I'm no graphics expert; I'm sure the algorithms have been researched,
though. You could find/write an implementation of such an algorithm, then
write a custom bridge for Batik so you could access it. [of course, it'd
only work with Batik at that point...]
Good luck.
- Bibek
On Wed, 4 Feb 2004, don undeen wrote:
> So you're saying that while there isn't code in batik to see if to SVG shapes intersect, I can turn them into java.awt.Shapes, and use code like jPong.PongObject.collides(shape1, shape2) to see if they collide?
>
> that makes sense; I wonder if that will ulitimately be practical for my
> system, where I intend to to have LOTs of shapes moving around. For N
> objects, I have to do (n+(n-1)+(n-2)+...+2+1 (i forget, is that what
> they'd call "O(log(n))" ?) comparisons every iteration to see if there
> are any new intersections. I've been able trying to avoid loops like
> that where possible.
> What I really wanted to have was a way to register a "collisionEvent"
> with a shape, so that collisions are just "announced" when they occur.
> Would something like that ever be in the works for SVG?
>
>
> Bibek Sahu <sc...@dodds.net> wrote:
>
> Howdy,
>
> On Wed, 4 Feb 2004, don undeen wrote:
>
> > Is there any way with batik/java/svg to detect if two svg shapes have
> > "collided" or overlap? For example, if you have two circles of some
> > radius, and you move them closer together, I'd like an alert to go up
> > when the edges collide. Or perhaps I'd like to know if two lines
> > overlap.
>
> In principle, in SVG, the SVGSVGElement methods 'getEnclosureList()',
> 'getIntersectionList()', 'checkEnclosure()', and 'checkIntersection()' might
> be useful (though I don't know if they'd be enough)... but in practice I
> don't think they're implemented in Batik yet (at least, that the impression
> I got from what I've seen on this list).
>
> In practice with Batik, you can get the GraphicsNode associated with an
> SVGElement, and then use GraphicsNode.getOutline() (or if it's a
> ShapeNode, use ShapeNode.getShape()) for both nodes, then check if the
> returned Shape objects intersect:
>
> BridgeContext bc = svgComponent.getUpdateManager().getBridgeContext();
>
> SVGElement circle1=...., circle2=....;
> GraphicsNode g1 = bc.getGraphicsNode(circle1);
> GraphicsNode g2 = bc.getGraphicsNode(circle2);
>
> Shape outline1 = g1.getGlobalTransform().createTransformedShape( g1.getOutline() );
> Shape outline2 = g2.getGlobalTransform().createTransformedShape( g2.getOutline() );
>
> if(outline1.intersects(outline2.getBounds2D()))
> // the first shape intersects the bounding-box of the second
> else
> // blah blah blah
>
>
> Note that it doesn't actually check if the two /shapes/ intersect, and
> especially with circles this could get to be a problem, but at least you now
> have Shape objects to work with. :-)
>
>
> If you need a method to see if two Shapes collide, Mr. Google is your
> friend. (e.g., http://www.risrani.com/programs/pong/doc-Pong/jPong/PongObject.htmlhttp://www.risrani.com/programs/pong/doc-Pong/jPong/PongObject.html
> ;-)
>
> Good luck!
> - Bibek
>
>
> > Is there a method to do this that doesn't involve explicitly calculating
> > the areas covered by each of my shapes?
> >
> > I'm guessing the answer is "no," but I'd sure like it to be "yes"!
> >
> >
> >
> > thanks for everything,
> >
> > Don Undeen
> >
> >
> >
> >
> > ---------------------------------
> > Do you Yahoo!?
> > Yahoo! SiteBuilder - Free web site building tool. Try it!
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: batik-users-unsubscribe@xml.apache.org
> For additional commands, e-mail: batik-users-help@xml.apache.org
>
>
> ---------------------------------
> Do you Yahoo!?
> Yahoo! SiteBuilder - Free web site building tool. Try it!
---------------------------------------------------------------------
To unsubscribe, e-mail: batik-users-unsubscribe@xml.apache.org
For additional commands, e-mail: batik-users-help@xml.apache.org
Re: detecting shape collision?
Posted by don undeen <do...@yahoo.com>.
So you're saying that while there isn't code in batik to see if to SVG shapes intersect, I can turn them into java.awt.Shapes, and use code like jPong.PongObject.collides(shape1, shape2) to see if they collide?
that makes sense; I wonder if that will ulitimately be practical for my system, where I intend to to have LOTs of shapes moving around. For N objects, I have to do (n+(n-1)+(n-2)+...+2+1 (i forget, is that what they'd call "O(log(n))" ?) comparisons every iteration to see if there are any new intersections. I've been able trying to avoid loops like that where possible.
What I really wanted to have was a way to register a "collisionEvent" with a shape, so that collisions are just "announced" when they occur. Would something like that ever be in the works for SVG?
Bibek Sahu <sc...@dodds.net> wrote:
Howdy,
On Wed, 4 Feb 2004, don undeen wrote:
> Is there any way with batik/java/svg to detect if two svg shapes have
> "collided" or overlap? For example, if you have two circles of some
> radius, and you move them closer together, I'd like an alert to go up
> when the edges collide. Or perhaps I'd like to know if two lines
> overlap.
In principle, in SVG, the SVGSVGElement methods 'getEnclosureList()',
'getIntersectionList()', 'checkEnclosure()', and 'checkIntersection()' might
be useful (though I don't know if they'd be enough)... but in practice I
don't think they're implemented in Batik yet (at least, that the impression
I got from what I've seen on this list).
In practice with Batik, you can get the GraphicsNode associated with an
SVGElement, and then use GraphicsNode.getOutline() (or if it's a
ShapeNode, use ShapeNode.getShape()) for both nodes, then check if the
returned Shape objects intersect:
BridgeContext bc = svgComponent.getUpdateManager().getBridgeContext();
SVGElement circle1=...., circle2=....;
GraphicsNode g1 = bc.getGraphicsNode(circle1);
GraphicsNode g2 = bc.getGraphicsNode(circle2);
Shape outline1 = g1.getGlobalTransform().createTransformedShape( g1.getOutline() );
Shape outline2 = g2.getGlobalTransform().createTransformedShape( g2.getOutline() );
if(outline1.intersects(outline2.getBounds2D()))
// the first shape intersects the bounding-box of the second
else
// blah blah blah
Note that it doesn't actually check if the two /shapes/ intersect, and
especially with circles this could get to be a problem, but at least you now
have Shape objects to work with. :-)
If you need a method to see if two Shapes collide, Mr. Google is your
friend. (e.g., http://www.risrani.com/programs/pong/doc-Pong/jPong/PongObject.htmlhttp://www.risrani.com/programs/pong/doc-Pong/jPong/PongObject.html
;-)
Good luck!
- Bibek
> Is there a method to do this that doesn't involve explicitly calculating
> the areas covered by each of my shapes?
>
> I'm guessing the answer is "no," but I'd sure like it to be "yes"!
>
>
>
> thanks for everything,
>
> Don Undeen
>
>
>
>
> ---------------------------------
> Do you Yahoo!?
> Yahoo! SiteBuilder - Free web site building tool. Try it!
---------------------------------------------------------------------
To unsubscribe, e-mail: batik-users-unsubscribe@xml.apache.org
For additional commands, e-mail: batik-users-help@xml.apache.org
---------------------------------
Do you Yahoo!?
Yahoo! SiteBuilder - Free web site building tool. Try it!
Re: detecting shape collision?
Posted by Bibek Sahu <sc...@dodds.net>.
Howdy,
On Wed, 4 Feb 2004, don undeen wrote:
> Is there any way with batik/java/svg to detect if two svg shapes have
> "collided" or overlap? For example, if you have two circles of some
> radius, and you move them closer together, I'd like an alert to go up
> when the edges collide. Or perhaps I'd like to know if two lines
> overlap.
In principle, in SVG, the SVGSVGElement methods 'getEnclosureList()',
'getIntersectionList()', 'checkEnclosure()', and 'checkIntersection()' might
be useful (though I don't know if they'd be enough)... but in practice I
don't think they're implemented in Batik yet (at least, that the impression
I got from what I've seen on this list).
In practice with Batik, you can get the GraphicsNode associated with an
SVGElement, and then use GraphicsNode.getOutline() (or if it's a
ShapeNode, use ShapeNode.getShape()) for both nodes, then check if the
returned Shape objects intersect:
BridgeContext bc = svgComponent.getUpdateManager().getBridgeContext();
SVGElement circle1=...., circle2=....;
GraphicsNode g1 = bc.getGraphicsNode(circle1);
GraphicsNode g2 = bc.getGraphicsNode(circle2);
Shape outline1 = g1.getGlobalTransform().createTransformedShape( g1.getOutline() );
Shape outline2 = g2.getGlobalTransform().createTransformedShape( g2.getOutline() );
if(outline1.intersects(outline2.getBounds2D()))
// the first shape intersects the bounding-box of the second
else
// blah blah blah
Note that it doesn't actually check if the two /shapes/ intersect, and
especially with circles this could get to be a problem, but at least you now
have Shape objects to work with. :-)
If you need a method to see if two Shapes collide, Mr. Google is your
friend. (e.g., http://www.risrani.com/programs/pong/doc-Pong/jPong/PongObject.htmlhttp://www.risrani.com/programs/pong/doc-Pong/jPong/PongObject.html
;-)
Good luck!
- Bibek
> Is there a method to do this that doesn't involve explicitly calculating
> the areas covered by each of my shapes?
>
> I'm guessing the answer is "no," but I'd sure like it to be "yes"!
>
>
>
> thanks for everything,
>
> Don Undeen
>
>
>
>
> ---------------------------------
> Do you Yahoo!?
> Yahoo! SiteBuilder - Free web site building tool. Try it!
---------------------------------------------------------------------
To unsubscribe, e-mail: batik-users-unsubscribe@xml.apache.org
For additional commands, e-mail: batik-users-help@xml.apache.org