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box2d collision filtering, can it be done?

question resolved using-vvvv Physics collision filtering box2d

effe 20/02/12 - 07:33

Hi all,

I've been trying to find some information on whether vvvv's implementation of box2d can handle collision filtering, and I've had some conflicting results.

First, there's this video:http://vimeo.com/9237177 by vux, which seems to demonstrate collision filtering. There's also the main feature list on this website which lists it as a feature.

However, I can't find any node which can do this, or information about said nodes. Also, there's a post by vux from two years or so ago which claims that it hasn't been implemented yet, and isn't a priority.

So I'm confused. Is it that vux has got it working, but just hasn't created a node to handle it yet? Or am I missing something.

Thanks.

6 replies 0 new

link | Flagged as solution by gaz. Remove solution flag. vux (kollaborateur) 20/02/2012 - 13:13

In the shape pins (Box/EdgeChain/Circle/Polygon), you need to set the group index pin to a negative value.

Any objects with the same negative value will never collide between each other.

To update group index on the fly UpdateShape(Box2d) can make you do that.

link | Flag this reply as a solution. effe 21/02/2012 - 02:49

Thanks heaps, that's very helpful.

link | Flag this reply as a solution. effe 18/04/2012 - 15:22

Hi again.

That works fine, but I'm wondering now if a slightly more complex interaction would be possible. Is it possible to create something like this:

Group 1: Collides with everything.
Group 2: Collides with Group 1 but not Group 3.
Group 3: Collides with Group 1 and itself, but not Group 2.

As far as I can see, setting negative values only works to stop a group from colliding with itself, not another group.

Thanks.

link | Flag this reply as a solution. effe 19/04/2012 - 01:56

I did a bit of googling and it seems like it can be done in box2d using maskBit and categoryBit, but I get the impression that these aren't part of vvvv's implementation of Box2d. Am I mistaken?

link | Flag this reply as a solution. vux (kollaborateur) 19/04/2012 - 14:12

Hello, indeed Collision Bits are not there, I'll look to add them for next release thanks.

link | Flag this reply as a solution. effe 20/04/2012 - 10:48

Awesome.

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Shoutbox

~35min ago

joreg: @tobi: use GetSlice() as the patch i referred you to is demonstrating. or start a forum thread with your patch.

~47min ago

TobiTobsen123: hmm yes i can see the values...but how to handle them as seperate values? I need to forward them via TCP/IP...

~2h ago

joreg: @tobi: OSCDecoder helppatch has a section: OSC_Advanced (bottomright) that demoes decoding of multiple messages

~3h ago

TobiTobsen123: I'm using an OSCDecoder, it receives two arguments...works but how can I seperate the arguments into two seperate values

~5h ago

u7angel: @mediadog, make it a forum question.

~5h ago

u7angel: @mediadog, tty renderer ?

~8h ago

microdee: however non-conductive objects are invisible for this so the pencil and the sticks in the video are still a mysteries

~8h ago

microdee: hey i just found a possible solution behind leap's black magic http://www.quora.com/Leap-Motion/What-is-the-technology-behind-Leap-Motion
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