Real-Time Physics Simulation Forum

Now that Bullet supports double precision, I'm wondering if that would help with using small objects? Some objects are quite small (a few centimeters with units in meters) and they tend to fall through the geometry sometimes. Will using double precision help me here? What should I change? Thanks, KenD

After all the big changes to Bullet lately I thought it was about time I update to the latest version before I get too far behind. I came across a small bug though. In btOptimizedBvh::~btOptimizedBvh() the delete should be an array delete. delete[] m_contiguousNodes; Also, can we get a getW() method...

What gravity value do you use? Do you have some mapping from units to meters? If you choose 9.8 for gravity, you can consider 1 unit = 1 meter, if you use real time steps. So the minimum 'recommended' size would translate to about 20 centimer, for a margin of 0.04. If you look at most games, you wi...

A long thin box below the collision margins is not well supported, so best avoided if possible: having any side of smaller then say 0.20 units is highly unrecommended. Ignoring that will result in jitter and failing simulation, unfortunately. The 'floating' is likely because the trianglemesh has a ...

The minimum objectsize is mostly for dynamic objects, so I wouldn't worry about static triangle meshes. It's more about dynamic convex hull/box/sphere/cylinder/cone. This 'minimum size requirement' is due to the collision margin and contact point reduction. Those (independent) values are currently ...

I suppose you mean collision time spend in the broadphase? There is no static trimesh versus static trimesh narrowphase. Do you use 3d axis sweep and prune (AxisSweep3) ? I'll check what we can do about this extra overhead indeed. Thanks, Erwin Yes, broadphase and I use AxisSweep3. If you can find ...

I have read the posts about size restrictions on objects etc. In my game the bounding box size of some objects can go down to 0.02 or so in one axis. My understanding is that this is too small to be reliable. So I was thinking that I could scale up everything for bullet by 10 (as an example). Is my ...

The static terrain meshes are all loaded and available when bullet is initialized. The problem is that when each mesh is in its own TriangleIndexVertexArray there are a lot of collisions between these static meshes and this slows it down. Basically what I'd like to see is a way to avoid processing t...

Yes, that approach would work but it means having an extra copy of the vertex data and I don't want to do that. It could be quite a lot in my case.
Erwin will have a demo later showing how to do it so I'll wait for that.

Ken

Erwin, can you explain how to add more meshes to a shape? If the vertices of the shapes were in one big array it could be done but they are of course separated into their own structures and objects. I can't see a way to add more triangle arrays after the BvhTriangleMeshShape object is created. I'm n...

Hi, First let me say that I'm no physics expert, just normal game and college math. I've decided to use Bullet in my game engine and I have a terrain mesh that is split up in many parts. I have taken the base set up from the Concave demo since it also uses a "terrain" mesh. I have created ...