Another 'Which physics SDK?' thread...

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6 comments, last by GameDev.net 19 years, 6 months ago
Hi all, Yet another SDK thread, but hopefully a bit more directed... Having tasted how long it takes to write physics stuff, I've finally decided to go pre-fab, but don't have the SDK knowledge to decide which one to use as my requirements are so diverse. Can anyone suggest a suitable SDK bearing in mind the following: a) Need to simulate buoyancy (I know [ed]Newton & Meqon do buoyancy) b) Need to model an approximation of a car (ODE has direct support I think) c) Need to interact with many separate heightmaps (islands) (looks to be a recent addition hacked onto some sdk's) d) My world is HUGE, and the SDKs I've seen only cater for small worlds, so I'll need to account for this somehow (create separate physics 'worlds' where required? May have trouble with discontinuities?!) e) Need to model continuous flight throughout this large world (maybe have to divorce flight model from the physics? :() [ed] ta Dom [Edited by - Aph3x on October 13, 2004 8:09:53 AM]
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"Tokamak & Meqon do buoyancy"

Tokamak does not. Newton has some.
_________________Dom's Blog
Most mature SDKs (ODE, Novodex, ...) can be used for such a scenario. Most likely, you won't get everything out of the box, though (like paging, caching, etc). Sometimes a few features have to be added (e.g. buoyancy in ODE) but that shouldn't be too hard.

Btw, cars in ODE are 'directly' supported in the sense of that there's a physics car object of some kind. But you can quite easily create such a model.

-codeandroid
Some feedback on ODE, which i've been using for more than a year now:

1. It's not the fastest nor the most stable library out here, but it's free!

2. AFAIK there is no "direct" support of cars in ODE - but you can easily assemble one by using spheres, boxes and the correct joints.

3. ODE also has support for heightmaps collisions.

4. It can handle pretty large world - i currently have collisions working with a 800 millions triangle mesh model (although i spent a bit of time integrating streaming functions in ODE).

5. It's sometimes pretty hard to adjust the set of parameters correctly in order to get the behavior you want.

Y.
For the record 800 hundred million polygons is not a measure of anything at all. As far as I know all physics engines handle static meshes of unlimited number of polygons and vertices. As for streaming functionality, if it can be implemented in ODE it can be added to any other engines since all of them provide an interface for custom designed static collision mesh
Roberto
Well, the problem of choosing a physics sdk is about come over my head too... so just a quick question here - I've heard that Novodex is almost as good as Havok. Is this true? What are some of the down/up sides of Novodex?
If you want to model a car, ODE can do that. It takes a while to set up, of course, you can't just create a "car" object or something. You'd need to do it at least semi-realistically.

I suggest you download the XPandRally demo. That uses ODE for physics, and it's amazing.

Apparently, they modelled each of the components of the car realistically, (i.e torques at various rpm's, etc., differentials, the works), and the "simulation" mode of the game is how it turned out, when they put it all together.

I've heard that the handling is pretty realistic, although the guy who told me admitted he isn't actually a rally driver :), so it was hard for him to be sure :p.

Apparently, it's so difficult to control (well, for a beginner), that they had to add an additional mode, "arcade" which is pretty close to Colin McRae 2's simulation mode handling. Simulation being more for the "fanatic".

I've used ODE personally and I love it. I love not having to write collision detection functions, having to worry about whether objects penetrate, etc.. It does take long to tweak the parameters, but IMO it's worth it.
We scratch our eternal itchA twentieth century bitchWe are grateful forOur Iron Lung
Novodex is provably the fastest engine but it is not the more realistic engine by any stretch of the imagination. When you stack objects the friction is fake, and if you apply force down to a body it behaves like sponge. It is closer to a penalty method solver than to a rigid body simulator, however it is a comercial engine very fast and feature complete.

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