BEPU 2.0 - int or short for collision meshes?

Discuss any questions about BEPUphysics or problems encountered.
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BrightBit
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BEPU 2.0 - int or short for collision meshes?

Post by BrightBit » Tue Feb 07, 2017 3:58 pm

Hello,

I'm currently refactoring the code of my current Unity 3D project and added a mechanism to split up large meshes (more than 64k vertices) into smaller pieces due to Unity using unsigned shorts for their vertex indices. As far as I can see BEPU 1.0 is using ints for its collision meshes, so I won't have to do the same thing for collision meshes, will I? Will BEPU 2.0 also use ints for its vertex indices?

BTW: Are there any updates regarding BEPU 2.0? I'm really looking forward to it. :)

Norbo
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Re: BEPU 2.0 - int or short for collision meshes?

Post by Norbo » Tue Feb 07, 2017 7:43 pm

It will almost certainly use ints. Large meshes are way too common not to directly support. I don't have to worry about supporting old/mobile graphics hardware, so the only real concern is performance. Unlike a rasterization pipeline with a near-passthrough VS, runtime use of indices is usually restricted to collided triangles and every collision requires a lot of work that makes the triangle sample trivial. (And if the memory capacity required by 4 byte indices is a problem, it is probably an indication that something very strange is going on, and there is probably a better solution than using 2 byte indices.)

Deforming meshes or other use cases where index bandwidth is actually significant in some phases may benefit from shorts, but that's an extremely rare use case and I am not sure how large the benefit would actually be. Even if it were valuable, I'd probably just create a dedicated short path in addition to the int path.
BTW: Are there any updates regarding BEPU 2.0? I'm really looking forward to it.
I'm currently fiddling with the solver. In the interest of not sticking my foot into my mouth in the event that I find some terrible bug in the implementation that destroys all my measurements, I won't excitedly blab about the perf numbers yet. But so far, things appear to be exceeding expectations :P

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BrightBit
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Re: BEPU 2.0 - int or short for collision meshes?

Post by BrightBit » Thu Feb 09, 2017 10:46 am

Sounds great! :)

Side note: I just read that Unity is planning to support 32 bit index buffers in the future as well.

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