Physics engine woes.

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22 comments, last by jovani 18 years, 9 months ago
Okay, so I went physics engine shopping. I heard Tokamak was very good and quick, so I read about it and decided to try it. Downloaded, installed and wrote a test program in less than a day (falling cubes) and I was quite pleased, until I tried implementing more complex stuff, like a very thin plane and a convex mesh. Pretty quickly, I figued out Tokamak had problems with thin objects (stuff goes through them) and that convex meshes weren't really implemented yet. I must say, I am very disappointed, since I REALLY need convex meshes for my engine, even if I can live with some collision errors. So, I moved on, and tried Newton and True Axis (yes, two at a time). Newton didn't seem stable from what I could see in the demos, and since True Axis looked much better, I gave that a whirl. Took me less than an hour to port my cubes sample to True Axis, but when I was done, and tried to add in a convex mesh -- it simply wouldn't collide with anything. I checked the net, and apparently, this wasn't implemented well either. So, I decided to do some research, and came up with Novodex, being a good engine, on all accounts I could find. So, I download that and start reading the documentation, and well, it's simply not documented. I mean, it's SO complicated (which could be good), but I'm completely lost with it. There is absolutly 0 info about convex meshes anywhere in the documentation. Frankly, I havn't the slightest idea what to do, and which engine to go with. I'm looking for something that would let me add convex meshes on the fly (not compile them into a .BIN file first) and would allow me to easily perform collision with these meshes. I don't really need much more. Any suggestions here? which engine would be good? Is there any info on any of these engines that could help me out here? Thanks in advance, sorry for the long post.
Sirob Yes.» - status: Work-O-Rama.
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did you try ODE, mesh vs mesh tests are not considered entirelly stable, but they are there.
just like the engines sirob mentioned, ODE has not finished its implementation of trimesh vs trimesh collision.
It seems you are looking for something very special.
You tried all of then and none were good enough for you?
The only choices left are the very expensive ones but none of them are any better than what Novodex is, so you will probably have problem there too.
I think for what you want the only solution left is to write your own it is quite simple. Just read Baraff, and Mirty and move from there.
I think writing my own is above my head for now. I'm not really looking for anything these engines don't say they do, they just don't do it. I mean, it's all there, they just don't collide.

Anywho, I've decided to try Newton, though I'm not too pleased with it's design.

I'll report in when that's done.
Sirob Yes.» - status: Work-O-Rama.
Take it easy, it is very typical for beginners to make mistakes when starting to work with a physics engine. You need to set the proper conditions in your scene and follow the instructions because not engine is ideally perfect.
Maybe you are trying too hard and want instant gratification. Using a physics library is a little more involved than using graphics engine at first specially it you had not prior experience.
All the engines you mention are quite capable of handling convex hull collision (ODE been the exception), maybe the interface is not what you desire but the only way you will be completely happy is if you wrote it yourself
Well, I'm sorry if I seem a bit rash, and I'm switching engine really quickly.

The main reason I'm trying them all, is that I'm having a very easy time moving between them, they are quite similar.

I'm just having a REALLY hard time finding information on any of these engines.

I'll finish up with Newton (since I already started with it), if that fails I'll give True Axis another go, somehow, but I doubt Tokamak would be able to fit my needs.
Sirob Yes.» - status: Work-O-Rama.
You could ask for help on the respective forums. I would not put my hope too high on finding professional quality documentation on freeware libraries, hey commercial engine don’t even have that good doc either.
There is a reason for that, technical documentation is very expensive to produce and maintain, all theses projects run by one or two individual.
Usually you get the information on the forum or in some Wiki.

All I can say is:
Novodex SDK Free for Non-Commercial use!

http://www.ageia.com/novodex.html
newton is pretty decent as i can say from my experiences, and better trimesh
support is also in working:

http://physicsengine.com/forum/viewtopic.php?t=1491&start=0



Projects: Top Down City: http://mathpudding.com/

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