Search found 540 matches

by drleviathan
Fri Aug 16, 2019 3:45 pm
Forum: General Bullet Physics Support and Feedback
Topic: Multi-Agent Representation
Replies: 1
Views: 83

Re: Multi-Agent Representation

If you're doing Deep Robotic Learning (DRI) and Human Robot Interactions (HRI) then you probably want to be using pybullet and asking your questions in the pybullet forum channel.
by drleviathan
Thu Aug 15, 2019 4:10 pm
Forum: General Bullet Physics Support and Feedback
Topic: Attribute ?
Replies: 1
Views: 98

Re: Attribute ?

The statement: "when I add a polygon to a btTriangleShape" does not quite make sense. A btTriangleShape is just a triangle with three vertices and doesn't have polygons. Perhaps you meant a btTriangleMeshShape? btTriangleMeshShape is a pure virtual base class. The first non-virtual derived class is ...
by drleviathan
Thu Aug 15, 2019 3:28 pm
Forum: General Bullet Physics Support and Feedback
Topic: Problems occurred when the validation of the Bullet's accuracy with a bouncing ball test
Replies: 5
Views: 166

Re: Problems occurred when the validation of the Bullet's accuracy with a bouncing ball test

It has been reported in previous forum posts (which I wasn't able to find with a quick search) that an object will sometimes NOT bounce on collision when the substep is too small. Since I couldn't find those threads I have to rely on my memory which tells me the problem was seen at substeps of 1/100...
by drleviathan
Tue Aug 13, 2019 4:56 pm
Forum: General Bullet Physics Support and Feedback
Topic: Problems occurred when the validation of the Bullet's accuracy with a bouncing ball test
Replies: 5
Views: 166

Re: Problems occurred when the validation of the Bullet's accuracy with a bouncing ball test

This might affect things, you'll have to test: I don't think your world->stepSimulation() is doing what you think it is. You're specifying the "step" but not the "substep" duration and hence it uses the default substep of 1/60 sec. So your world "steps" forward in 1/600 sec increments and does nothi...
by drleviathan
Mon Aug 12, 2019 2:50 pm
Forum: General Bullet Physics Support and Feedback
Topic: Problems occurred when the validation of the Bullet's accuracy with a bouncing ball test
Replies: 5
Views: 166

Re: Problems occurred when the validation of the Bullet's accuracy with a bouncing ball test

I dunno the answer but I have some questions about your simulation: (1) What was your simulation stepping strategy? Fixed substep? If so, what was its duration? How man max substeps? (2) Are you using single or double precision? (3) Your ball was an implicit btSphereShape , I assume, but what shape ...
by drleviathan
Tue Aug 06, 2019 9:54 pm
Forum: General Bullet Physics Support and Feedback
Topic: Soft Body rendering from OBJ model (data extraction)
Replies: 2
Views: 174

Re: Soft Body rendering from OBJ model (data extraction)

I started looking at the btSoftBody code to see if I could provide some insight. I don't fully understand it yet but it looks like btSoftBody::m_faces is a btAllignedObjectArray<btSoftBody::Face> and a Face is a "triangle" that has pointers to three Nodes . struct Face : Feature { Node* m_n[3]; // N...
by drleviathan
Mon Jul 22, 2019 3:11 pm
Forum: General Bullet Physics Support and Feedback
Topic: Error while trying to link BulletRobotics
Replies: 1
Views: 178

Re: Error while trying to link BulletRobotics

The linker can't find the file: /usr/lib/gcc/x86_64-linux-gnu/libdl.so Look for it to see if you have it. The file path relies on you having a directory called: / usr/lib/gcc/x86_64-linux-gnu/5/ Do you have that directory? That appears to be an old version of gcc . On my linux machine I see 6 and 7 ...
by drleviathan
Tue Jul 09, 2019 4:51 am
Forum: General Bullet Physics Support and Feedback
Topic: Execute direct kinematics with btHingeConstraint
Replies: 4
Views: 451

Re: Execute direct kinematics with btHingeConstraint

After a bit of cleanup for readability your old code looks like this: btVector3 pivotAnchor(0,0,200); btVector3 pivotSpinner(0,0,200); btVector3 axisAnchor(0,1,0); btVector3 axisSpinner(0,1,0); btHingeConstraint joint = new btHingeConstraint(anchor, spinner pivotAnchor, pivotSpinner, axisAnchor, axi...
by drleviathan
Sun Jul 07, 2019 3:52 pm
Forum: General Bullet Physics Support and Feedback
Topic: Execute direct kinematics with btHingeConstraint
Replies: 4
Views: 451

Re: Execute direct kinematics with btHingeConstraint

It would be helpful if you were to supply source code. It is hard to make sense of what you are doing wrong from your description, however I will hazard some advice: From your description it sounds like you are using world-frame coordinates. However the transforms in the btHingeConstriant constructo...
by drleviathan
Fri Jun 28, 2019 3:45 pm
Forum: General Bullet Physics Support and Feedback
Topic: Undefined reference from bullet 2.72 to 2.81
Replies: 3
Views: 2209

Re: Undefined reference from bullet 2.72 to 2.81

The btCapsuleShape is inside the BulletCollision library. We must conclude the linker is unable to find the library itself.
by drleviathan
Thu Jun 27, 2019 4:03 pm
Forum: General Bullet Physics Support and Feedback
Topic: Objects bounce away violently
Replies: 5
Views: 526

Re: Objects bounce away violently

That old thread is still correct except for one thing: Using btCompoundShape is not the only way to go. The OP might have been able to use Bullet's GImpactShape stuff which allows for dynamic convex shapes. I would sum it up like so: (1) btTriangleMeshShape can NOT be used for dynamic objects. The r...
by drleviathan
Thu Jun 27, 2019 1:58 pm
Forum: General Bullet Physics Support and Feedback
Topic: Objects bounce away violently
Replies: 5
Views: 526

Re: Objects bounce away violently

The little boxes are using btTriangleMeshShape? Or just the big cyan container? Bodies that use btTriangleMeshShape cannot be dynamic else Bad Things happen.
by drleviathan
Wed Jun 19, 2019 5:41 pm
Forum: General Bullet Physics Support and Feedback
Topic: How to import stl file and make it a rigid body
Replies: 8
Views: 1808

Re: How to import stl file and make it a rigid body

Now that I look back at this issue I notice: it doesn't look like the OP was creating the motionState and then not using it. The motionState is a "bridge" object between the btRigidBody and the GameObject (rendered thing). One should at least supply the motionState to the btRigidBody constructor, an...
by drleviathan
Tue Jun 18, 2019 4:33 pm
Forum: General Bullet Physics Support and Feedback
Topic: Using Bullet for plain, accurate, convex intersection detection.
Replies: 5
Views: 562

Re: Using Bullet for plain, accurate, convex intersection detection.

I don't know how to do it exactly but merely mention it as a possibility. You'd have to identify the GJK parts, study its API, and figure out how to make it do what you want. Dunno how or if Bullet's GJK algorithm can be fine-tuned.
by drleviathan
Tue Jun 18, 2019 4:21 pm
Forum: General Bullet Physics Support and Feedback
Topic: Collision margin in BoxShapes.
Replies: 5
Views: 566

Re: Collision margin in BoxShapes.

How do you extract the worldTransform of the RigidBody ? Are you using something like DefaultMotionState::getWorldTransform() ? If so then the following issue may apply: Bullet's MotionState API will supply an extrapolated transform to the MotionState rather than the RigidBody 's true transform at t...