Real-Time Physics Simulation Forum

I often find myself creating new bullet worlds for specific effects in my game -- for example, if I want to have floppy rabbit ears that don't collide with anything, it seems most intuitive to just create a new world for each rabbit. If I want to perform proximity collision, I make a world populated...

In my game project, I do a lot of very similar collision queries. For instance, if a character is walking across a surface, I sweep a small sphere downwards from above each foot to get the ground position for inverse kinematics. Similarly, visibility checks works by tracing a ray from one character'...

There are a number of cases where the automatic moment of inertia is not sufficient for a complex object with a convex hull, since it assumes uniform mass distribution within the hull's bounding box. An extreme example would be a lollipop -- the mass distribution is almost all in the sphere at the e...

I can use the contactTest function to get all of the btManifoldPoints for the collision, but now I would like to figure out what the normal sliding collision response would be. This is useful for a lot of things that I want to simulate at a higher fidelity than the overall physics scene, like camera...

Thanks! I can successfully create spring-like behavior, but I am having trouble figuring out exactly what parameters will result in the pose being 100% matched, 50% matched, and so on, so that I can control it in a precise way. That is, I'm trying to act on the angle velocity directly in this manner...

I am working on animation for my new game, more specifically I am working on partial ragdolls. For example, in a walking animation I can set the character's arms to be only partially kinematic so that they swing a little when changing direction. Currently I am using btHingeConstraint and Generic6Dof...

I suspect you will either have to convert your data into a heightfield and use the btHeightfieldTerrain shape, or triangulate it and use a btBvhTriangleMesh shape.

Thanks for the advice! To the end of btAdjustInternalEdgeContacts() I added: And now it gives a single-sided collision response.

For now I'm just using a point2point constraint with a near-zero m_impulseClamp value -- I figured that would be less expensive than the btGeneric6DofConstraint. So far it seems to be working ok, but I'll file a feature request if it turns out to be too expensive and the other solutions are not suff...

When a rigid body collides with a btBvhTriangleMesh shape, the collision response seems to ignore the orientation of the triangle face (i.e. clockwise or counter-clockwise), and instead, determine which direction to move based on whichever side is closer. This means that if a sphere of diameter 1 is...

One way to do this might be to add a btGeneric6DOFConstraint just for friction, with all the limits constantly set to their current state. Then you can control the friction by changing the paramaters of the btTranslationalLimitMotor and btRotationalLimitMotor. I haven't tried this myself, but I'm pl...

In my brief tests it looks like that could be caused by the two-sided triangles -- sometimes my ragdolls will get stuck halfway through an object because some objects are being pushed out by the correct side, and some are being pushed in by the incorrect side. In ODE this didn't happen for me becaus...

When using constraints it's possible to disable collisions using the second parameter of btDynamicsWorld::addConstraint(btTypedConstraint* constraint, bool disableCollisionsBetweenLinkedBodies). But what if I want to disable collisions between two objects without any constraint? Right now I think I ...

If I need to create a capsule that connects two points, is there any reason not to use a multisphere for convenience? How does its performance compare to a capsule?

Disclaimer: I only started using Bullet a few days ago and may not know what I'm talking about. However, I am also using a btBvhTriangleMeshShape for my ground terrain. One thing I noticed is that triangle collision seems to be two-sided. That is, if your rocket is more than halfway through the terr...