Search found 744 matches

by drleviathan
Tue Oct 26, 2021 12:07 am
Forum: General Bullet Physics Support and Feedback
Topic: Collision Shape From FBX SDK Vertices
Replies: 3
Views: 166

Re: Collision Shape From FBX SDK Vertices

Sorry, I misunderstood the collision problems you were describing: it sounded like the mesh objects were moving around. I re-read your post more carefully and offer this numerated summary of the problems you are experiencing, with some re-wording for clarity. If I got any of these wrong please offer...
by drleviathan
Mon Oct 25, 2021 3:07 pm
Forum: General Bullet Physics Support and Feedback
Topic: Collision Shape From FBX SDK Vertices
Replies: 3
Views: 166

Re: Collision Shape From FBX SDK Vertices

btBvhTriangleMeshShape only supports static objects, not objects with non-zero velocity. For dynamic objects use btCompoundShape with convex decompositions of your concave shapes, or maybe the GImpactShapes.
by drleviathan
Sun Oct 10, 2021 8:09 pm
Forum: General Bullet Physics Support and Feedback
Topic: Required Libraries
Replies: 3
Views: 474

Re: Required Libraries

Yeah, that is confusing. I think what happened was this (and someone please correct me if I'm wrong): Bullet3 started as an effort to leverage GPU computation to do physics however progress on that front stalled. Meanwhile, Bullet2 was still being used and improved.. and eventually the C-API and PyB...
by drleviathan
Sat Oct 09, 2021 3:31 pm
Forum: General Bullet Physics Support and Feedback
Topic: Required Libraries
Replies: 3
Views: 474

Re: Required Libraries

What do you really want to do? That is, you want to sort and organize the libraries for what purpose? The Bullet source repository comes with a few optional extras but even some of the core Bullet libraries are optional depending on what kind of application you're building. For example libBulletSoft...
by drleviathan
Wed Oct 06, 2021 11:09 pm
Forum: General Bullet Physics Support and Feedback
Topic: A problem with a sphere rolling on terrain
Replies: 1
Views: 199

Re: A problem with a sphere rolling on terrain

The rotation out is in Quaternion form, which is a 4D object, not a Vector3. Your could should look more like:

Code: Select all

private static Quat4f getBallRotation(RigidBody ball)
{
    Quat4f out = new Quat4f();
    ball.getMotionState().getWorldTransform(new Transform()).getRotation(out);
    return out;
}
by drleviathan
Fri Oct 01, 2021 3:51 pm
Forum: General Bullet Physics Support and Feedback
Topic: Inverse Kinematics Functionality
Replies: 1
Views: 163

Re: Inverse Kinematics Functionality

Try asking your questions in the pybullet support section of the forum.
by drleviathan
Fri Oct 01, 2021 5:28 am
Forum: General Bullet Physics Support and Feedback
Topic: J impulse is wrong in all Physics Engines
Replies: 3
Views: 1561

Re: J impulse is wrong in all Physics Engines

This rings a bell... I recall having the exact same thought but eventually convinced myself that it was wrong and the books are correct. As I recall the line of reasoning was... If you apply an impulse at a point such that the lever-arm (from the center of mass) is perpendicular... you still end up ...
by drleviathan
Tue Sep 28, 2021 8:53 pm
Forum: General Bullet Physics Support and Feedback
Topic: Multithreaded simulation in Bullet3
Replies: 1
Views: 274

Re: Multithreaded simulation in Bullet3

There is a big thread about the history and progress at running a multithreaded bullet simulation. I haven't read it carefully so am unable to offer a summary.
by drleviathan
Wed Sep 15, 2021 4:01 pm
Forum: General Bullet Physics Support and Feedback
Topic: Rigid body with child sensors
Replies: 5
Views: 1346

Re: Rigid body with child sensors

Those collision filter groups are there for your convenience; they are completely optional. If you examine the Bullet source code you'll find they are declared in a header but never actually used anywhere except in an example. To get what you want I think you need to something like this before you a...
by drleviathan
Wed Sep 15, 2021 2:32 pm
Forum: General Bullet Physics Support and Feedback
Topic: Rigid body with child sensors
Replies: 5
Views: 1346

Re: Rigid body with child sensors

To make a ghost object that follows a body I use an action. I derive GhostFollowsBody from the pure virtual base class btActionInterface and implement its updateAction() method like so: class GhostFollowsBody : public btActionInterface { btRigidBody* m_body; btGhostObject* m_ghost; public: void Ghos...
by drleviathan
Sat Sep 11, 2021 7:05 pm
Forum: General Bullet Physics Support and Feedback
Topic: btCompoundShape of convex hulls not rendering in BasicExample
Replies: 3
Views: 833

Re: btCompoundShape of convex hulls not rendering in BasicExample

Typically math libraries that have been optimized will NOT initialize object components to default values in the default ctor. This to avoid wasted CPU cycles for the cases where the default values are immediately overwritten. As such they require the Application developer to explicitly initialize. ...
by drleviathan
Sat Sep 11, 2021 6:34 pm
Forum: General Bullet Physics Support and Feedback
Topic: Object falls a third of its height through the ground
Replies: 9
Views: 1821

Re: Object falls a third of its height through the ground

Setting the inverse inertia diagonal to zeros is fine: it produces an object that will never ever rotate from external forces, which is often what you want for a character. With dynamic characters I typically push them around with velocity adjustments, allow them to rotate about the vertical axis, b...