Bezier Patches - cool, or useless?

[simplicity]

I was reading the Gamasutra article about Climax Brighton's use of bezier patches in MotoGP. http://www.gamasutra.com/features/20020626/hargreaves_02.htm

The author (Shawn Hargreaves) makes a compelling case for using Bezier patches for modeling non-animated characters and landscape. But he says you need to write your own tools to do the modeling, as existing tools don't handle bezier patches very well.

He also mentions that on the PS2 version of MotoGP they tessalate the bezier patches at runtime, to save RAM.

Doing a google search, it looks like Shawn Hargreaves is a lone voice in the wilderness -- he's pretty much the only one advocating use of bezier patches.

On the other hand, Moto GP looks really good! So maybe he's on to something.

I'm not sure, but Climax Brighton may be using bezier patches in Sudeki for character modeling.

What do you-all think of bezier patches? Are they going to be commonly used in games (I know Quake3 allows them as modeling primitives), or are they going to lose out to subdivision surfaces (which are much easier to model, and may be only slightly slower to render.)

 

[MfA]

A couple more X-Box games will use it maybe ... and that will be about it.

If ATI too had gone with bezier patches, or rather polynomial patches, like they should have we might have seen them used on the PC and they might have become an integral part of DX9 (N-Patches are a half assed subset of bezier patches which are no easier to render and which take control over the surface away from developers for negligible gain in storage requirements ... for the average incompetent PC developer they could still have provided an automated convertor from triangle meshes to bezier form without any trouble). Instead the hardware and software developers managed to conspire to screw the pooch, so now we are just stuck with lots of memory sucking triangles.

If we are going to see widespread use of HOS on the PC it will be after hardware provides programmable tesselation IMO. When that is the case I expect developers to mix and match the different forms of HOS, after sticking to triangles for another couple of years because of legacy hardware of course.

 

[simplicity]

Thanks for the insight, MfA. I wonder when PC GPUs will start having programmable vertex shaders capable of tessalation.

One thing I wanted to point out from the paper I referenced is that the Xbox version of MotoGP does not use Bezier patches at runtime. Only the PS2 does. Apparently drawing using the Xbox GPU's Bezier patch tessalation hardware is slower than drawing using an offline-optimized polygon mesh created from the original Bezier patch data.

 

[Hyp-X]

With neigther the R300 nor the NV30 supporting any form of HOS in hardware I can't see this gaining support anytime soon...

At least DX9 supports packed vertex component formats, so one can relax the memory required somewhat (but not nearly so much as HOS would allow it).

 

[KimB]

If ATI too had gone with bezier patches, or rather polynomial patches, like they should have we might have seen them used on the PC and they might have become an integral part of DX9 (N-Patches are a half assed subset of bezier patches which are no easier to render and which take control over the surface away from developers for negligible gain in storage requirements ... for the average incompetent PC developer they could still have provided an automated convertor from triangle meshes to bezier form without any trouble). Instead the hardware and software developers managed to conspire to screw the pooch, so now we are just stuck with lots of memory sucking triangles.

There may have been other reasons why the bezier patch support was dropped. I've heard hints (haven't verified these myself) that the HOS support in the GeForce3/4 was dropped largely because of performance reasons.

Anyway, hopefully we'll get some good HOS implementations soon...it's really going to be necessary to leverage the vertex processing power of future graphics cards (not just for memory bandwidth reasons, but also for scalability reasons).

 

[elchuppa]

that's interesting... in any case the xbox version is so much better looking, I can only assume it is not missing much.

I have to say motogp is one of my favourite games ever.
Practically flawless, a masterpiece.