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View Full Version : Heavy Bullet Dynamics scenes are crashing on simulation. Any way to remedy this?



Dennik
04-29-2013, 08:28 AM
I have some scenes to simulate that include at least 2 million polygons and close to 30,000 parts exploding. (Somehow I got to fracture a model in 30,000 parts which is a feat on its own.)
My win7 64bit 24gb ram machine cannot handle it. At least lightwave can't cause its crashing after thinking about it for a few hours.
Is there any way to make this work? I'm using convex shapes at this point.

dsol
05-02-2013, 11:13 AM
I feel your pain. LW bullet dynamics ain't nearly as stable as I'd like - really needs better support for low-poly proxies for collision (yes, I know that's what convex does generate - but i'd like to have manual control over the mesh proxies used). It's also not helped by the way that fracture sometimes seems to produce geometry which isn't airtight.

In the meantime, the only thing I can suggest is breaking up your simulation as much as possible into smaller chunks (and smaller scenes) and then baking out successfully generated dynamics objects. That's how I got my 1xtra Phone animation (http://forums.newtek.com/showthread.php?134665-BBC-Radio-1xtra-quot-Bassphone-quot-promo&highlight=radio+1xtra) to work in the end.

MarcusM
05-02-2013, 01:16 PM
For example in Unity for "low poly" object you can set up collider as a different mesh, less complicated object what have the same shape/borders.
That option in bullet dynamics in LW would speed up calculations. (Not for exploding objects with many parts...;\).
Am i right that bullet dynamics in LW not using CUDA?

3DGFXStudios
05-02-2013, 02:28 PM
For example in Unity for "low poly" object you can set up collider as a different mesh, less complicated object what have the same shape/borders.
That option in bullet dynamics in LW would speed up calculations. (Not for exploding objects with many parts...;\).
Am i right that bullet dynamics in LW not using CUDA?

Convex pieces makes simple geometry. If you check draw collision shapes you can see it.
Noop...No cuda in LW....

MarcusM
05-02-2013, 02:38 PM
Convex pieces makes simple geometry. If you check draw collision shapes you can see it.
Noop...No cuda in LW....

Ok
I checked simple case, parenting almost 2 milion poly sphere to 180 poly sphere. Lower res was rigid body and it is working of sourse much faster.

dsol
05-02-2013, 05:14 PM
Convex pieces makes simple geometry. If you check draw collision shapes you can see it.
Noop...No cuda in LW....

Yep, and I said as much in my post. But for certain objects (like the phone in my animation) it would have been way more efficient if I could have used my own low-poly mesh for physics interactions.

EDIT: and I believe there's an OpenCL version of Bullet in development - for a while now IIRC - but it's not stable enough yet to be folded back into the main fork yet

Dennik
05-09-2013, 04:28 PM
.....In the meantime, the only thing I can suggest is breaking up your simulation as much as possible into smaller chunks (and smaller scenes) and then baking out successfully generated dynamics objects. That's how I got my 1xtra Phone animation (http://forums.newtek.com/showthread.php?134665-BBC-Radio-1xtra-quot-Bassphone-quot-promo&highlight=radio+1xtra) to work in the end.



I thought initially about baking it in layers like that. Unfortunately, I need to show interaction between those layers, and if one layer is baked, it won't be truly interacting with the other layer.

Dennik
05-09-2013, 04:45 PM
Further problems: I'm trying to merge two separate bullet scenes. Lightwave stops working and windows is shutting it down. I'm trying different options but every time I load a scene, I have to wait through a long time of the decomposing process. This is ridiculous.