Search found 13 matches

by amatic
Thu Feb 04, 2016 3:28 pm
Forum: General Bullet Physics Support and Feedback
Topic: Hill-Type Muscle - Non linear spring
Replies: 1
Views: 3436

Re: Hill-Type Muscle - Non linear spring

I'm working on a similar thing. My current attempt is briefly described here, posted a few days ago: http://bulletphysics.org/Bullet/phpBB3/viewtopic.php?f=9&t=11022 It is not exactly the same as the hill-type muscle, but a variation described in this paper: http://www.livingcontrolsystems.com/i...
by amatic
Sun Jan 31, 2016 10:43 pm
Forum: General Bullet Physics Support and Feedback
Topic: Slider properties
Replies: 15
Views: 43846

Re: Slider properties

Do you need to restrict rotation of the bodies?
Or is it just wobbly?
by amatic
Wed Jan 27, 2016 12:07 pm
Forum: General Bullet Physics Support and Feedback
Topic: Modeling a muscle with a spring and a slider
Replies: 1
Views: 4490

Modeling a muscle with a spring and a slider

I'm making a model of a simple muscle as a spring constraint and a slider constraint in series. I'll need more muscles, so I'm making a class that takes two bodies and pivots on them and puts a muscle in between. End result should have: bodyA - spring - slider - bodyB, with handles for spring length...
by amatic
Wed Jan 20, 2016 11:37 am
Forum: General Bullet Physics Support and Feedback
Topic: How to specify slider constraint axis
Replies: 7
Views: 10127

Re: How to specify slider constraint axis

Hi I would like to dynamically create an axis for a btSliderConstraint at runtime between two rigid bodies. I have two rigid bodies in world space, I take there centre of mass positions and subtract one from the other to generate the axis. I think I might have a similar case, let me know if it work...
by amatic
Tue Jan 12, 2016 6:11 pm
Forum: General Bullet Physics Support and Feedback
Topic: Simple example of bullet with a GUI + bouncing ball
Replies: 4
Views: 6626

Re: Simple example of bullet with a GUI + bouncing ball

Just use the default browser, and then change the code in one of the examples so that there is a single ball spawned. You can also look at the older code on the google code section that has fewer fancy things, but even that won't have an example that simple because it's nearly trivial. Could you pl...
by amatic
Fri Jan 08, 2016 2:38 pm
Forum: General Bullet Physics Support and Feedback
Topic: Simple example of bullet with a GUI + bouncing ball
Replies: 4
Views: 6626

Re: Simple example of bullet with a GUI + bouncing ball

Any luck with Glitter? I would appreciate the source code of the example. The ExampleBrowser seems pretty complicated to me, too.

Also, what GUI widget library might be used with glitter?
by amatic
Fri Jan 08, 2016 11:47 am
Forum: General Bullet Physics Support and Feedback
Topic: Getting world coordinates of vertices of a convex hull body
Replies: 3
Views: 6149

Re: Getting world coordinates of vertices of a convex hull b

Should be something like "centerOfMassTransform * point " for each point i. point is the location of the vertex relative to the center of mass of the object, and centerOfMassTransform is a quaternion representing the translation and rotation of the object at some point in time. Multiplying...
by amatic
Mon Jan 04, 2016 4:24 pm
Forum: General Bullet Physics Support and Feedback
Topic: Solving collisions and constraints, causes unwanted movement
Replies: 3
Views: 5325

Re: Solving collisions and constraints, causes unwanted move

Did you try a different constraint solver?

Maybe something like this would help:

Code: Select all

m_constraintSolver = new btMLCPSolver(new btDantzigSolver());
I don't have a deep understanding of these things yet, but changing the solver and reducing simulation timestep seemed to have helped.
by amatic
Tue Nov 03, 2015 2:02 pm
Forum: General Bullet Physics Support and Feedback
Topic: Best way to simulate a gyro sensor?
Replies: 7
Views: 8833

Re: Best way to simulate a gyro sensor?

OK, this seems to work:

Code: Select all

  btTransform trans;
  body->getMotionState()->getWorldTransform(trans);
  trans.setOrigin(btVector3(0, 0, 0)); 
  btVector3 anglVel = trans.inverse() * body->getAngularVelocity();
by amatic
Mon Nov 02, 2015 1:16 pm
Forum: General Bullet Physics Support and Feedback
Topic: Best way to simulate a gyro sensor?
Replies: 7
Views: 8833

Re: Best way to simulate a gyro sensor?

Basroil, sorry if this is a very noob question, but how do I get angular velocity of a simulated body, in the same way a gyro gets the angular velocity of the body it is attached to? If I'm not mistaken, the getAngularVelocity() returns the rotation rate around 'global axes', while I would need some...
by amatic
Fri Oct 30, 2015 2:20 pm
Forum: General Bullet Physics Support and Feedback
Topic: Best way to simulate a gyro sensor?
Replies: 7
Views: 8833

Re: Best way to simulate a gyro sensor?

Thank you for the response. I'm quite a noob in this, so I'm not sure if those formulas apply for simulating something like this http://www.robotshop.com/en/sensors-gyroscopes.html ? I'm trying to make a balancing robot simulation. My first approach was to make a cart with 4 wheels, an inverted pend...
by amatic
Thu Oct 29, 2015 8:50 pm
Forum: General Bullet Physics Support and Feedback
Topic: Best way to simulate a gyro sensor?
Replies: 7
Views: 8833

Best way to simulate a gyro sensor?

Hi, I was wondering what would be the best way to simulate a gyroscope in Bullet. I would need it to be reusable, so I suppose they should have their own physics object, is that correct? Also, If getAngularVelocity gives rotation velocity around world axes, how do I get angular velocity of the body ...