Auto-updating animated selectors / scene triangle selection

rogerborg · Post by **rogerborg** » Sun Feb 01, 2009 7:08 pm

SVN 2177 has committed a couple of selector goodies to the trunk.

1) Triangle selectors that are created from animated mesh scene nodes will now auto-update themselves as necessary to keep in sync with their mesh. This means that you can now do triangle selection on animated meshes. Well, you can try. Go on, try, you pansies.

2) A new method, ISceneCollisionManager::getSceneNodeAndCollisionPointFromRay() allows selection on a scene node heirarchy. It will the ray against check each node, first by bounding box, then by ray/triangle selection, to find the closest collision point, triangle and node.

Example 07.Collision demonstrates both of these, doing triangle selection on a quake 3 level and 3 animated meshes with one method call. Oh yeah, baby.

Testing would be very welcome, particularly on skinned skeletal nodes.

Pyritie · Post by **Pyritie** » Sun Feb 01, 2009 8:43 pm

It's things like this that make me wish I had learnt C++ instead of Java. :B

Mel · Post by **Mel** » Wed Feb 04, 2009 3:42 pm

Updating....

By the way, good work with the light manager. looks REALLY interesting.

Why do you complain about it? Java and C++ are twins, the only thing C++ might lack is a resource manager to keep the memory clean, and that EVERYTHING in Java are pointers. Other than that, if you know Java, you know C++, you just need to get used to C++ manners

JP · Post by JP » Wed Feb 04, 2009 4:40 pm

Nice one on the autoupdatingselectors... i guess... it's something that's always been asked for but really it's something that's highly inadvisable in most cases innit? Updating all those triangles could be costly so instead of taking a cheaper route newbs will take this route and be all like awww man wah mah frayme rayt sew loh???

rogerborg · Post by **rogerborg** » Wed Feb 04, 2009 4:46 pm

The selector will only update if its node is hit with a ray-box check, and it will only update if the animation frame has actually changed since the last time the selector was updated. (i.e. if you create a selector from an "animated" node that doesn't actually animate, it'll never get updated, just as now).

What other optimisations could be applied?

JP · Post by JP » Wed Feb 04, 2009 4:53 pm

sounds pretty good actually, nice job!

Dorth · Post by **Dorth** » Thu Feb 05, 2009 7:03 am

Errr, hopefully I'm wrong about this, but:

Frame A
Box (0,0,0)-(1,1,1)

Frame B
Box (1,1,1)-(2,2,2)

Ok, I know it's an extreme case, absolutely no overlapping between the 2 aabb, but it's only for a demonstration. Btw, the aabb given here are relative to mesh's center, not node's position.

If I have a ray (1.5,-1,1.5)-(1.5,3,1.5), it will correctly not find a collision in frame A, but will it somehow update for Frame B? Or is my fear true and will it miss it?

rogerborg · Post by **rogerborg** » Thu Feb 05, 2009 11:17 am

Well, the code is committed, so...

Dorth · Post by **Dorth** » Thu Feb 05, 2009 5:36 pm

Heh, it's not as if I used it, so...

christianclavet · Post by **christianclavet** » Fri Feb 06, 2009 3:35 am

Thanks Rogerborg! That's really interesting. I'll try to get the last SVN and check this.

I really appreciate the fact that you update the demos to show the new implementation.

rogerborg · Post by **rogerborg** » Fri Feb 06, 2009 9:54 am

Great, thanks. At this point, it's definitely "experimental", so bug reports will be both welcome, and expected.