About btDbvtBroadphase and other approaches

[projectileman]

Hi.
I'm just learning about different BroadPhase collision strategies. And now btDbvtBroadphase keeps my attention.

Is there any advantages for using btDbvtBroadphase over other strategies like SAP (btAxisSweep3)?

Well this question is more concerned about performance, because it is clearly that the main advantage about btDbvtBroadphase is that it could manage large worlds.

And it seems that btDbvt is pretty efficient for updating body locations.

[Nathanael]

Compared to SAP, here's a short pro/con list:

Pros:
- Fast insertion, removal, update.
- Unbounded world space.
- Additional queries support: Ray-casting, Culling, Occlusion, LOD, etc...
- One data structure for physics and everything else in a game engine.

Cons:
- Lot of cache misses compared to SAP (can be improved).
- An hand optimized DbvtBroadphase should be slower than an hand optimized SAP on medium load (5k bodies) when used to broadphase only.

The current btDbvtBroadphase is a bit faster SAP in benchmarking cases on PC,

bullet_benchmark.zip

(73 KiB) Downloaded 367 times

but its mainly due to implementation, and i don't think those results extrapolate on 'slow branching' targets like xbox360.

Nathanael.

[projectileman]

Thanks a lot Nathanael.

I didn't make benchmarking about it before. But now I'm more interested in your Dynamic tree approach.

So thanks.