Search found 56 matches

by rponomarev
Fri May 29, 2009 12:49 am
Forum: General Bullet Physics Support and Feedback
Topic: Questions about the btGeneric6DofConstraint
Replies: 9
Views: 12924

Re: Questions about the btGeneric6DofConstraint

Hello,

Looks like your code should work with the latest version from trunk (I suppose that m_maxMotorForce is always positive)
Actually you need to update 2 files : btGeneric6DofConstraint.cpp and btGeneric6DofConstraint.h

Hope this will help,
Roman
by rponomarev
Wed May 27, 2009 9:53 pm
Forum: General Bullet Physics Support and Feedback
Topic: Questions about the btGeneric6DofConstraint
Replies: 9
Views: 12924

Re: Questions about the btGeneric6DofConstraint

Hello,

Try to upgrade to the latest trunk version - I recently committed a few fixes for the 6DOF constraint.
Anyway I'll try to reproduce this situation.
A little snippet of your code will really help :-)

Thanks,
Roman
by rponomarev
Thu May 21, 2009 6:25 pm
Forum: General Bullet Physics Support and Feedback
Topic: point to point spring constraint possible?
Replies: 6
Views: 10888

Re: point to point spring constraint possible?

Hello,

Do you mean a constraint where all rotational DOF are free, 2 translation DOF are locked and one translation has a spring motor?

In the next release (2.75) we'll have the btGeneric6DOFSpring constraint where you can set a spring to any DOF, so this should solve your problem.

Thanks,
Roman
by rponomarev
Wed May 13, 2009 9:58 pm
Forum: General Bullet Physics Support and Feedback
Topic: Questions about the btGeneric6DofConstraint
Replies: 9
Views: 12924

Re: Questions about the btGeneric6DofConstraint

Hello, Yes, the luck of documentation on 6DOF constraint is a problem. We'll try to cover this in the near future. Also we are going to simplify setup of ODE-like joints in the next Bullet version (2.75), see http://code.google.com/p/bullet/issues/detail?id=225 Looks like you didn't set frames and l...
by rponomarev
Tue Apr 07, 2009 9:23 pm
Forum: General Bullet Physics Support and Feedback
Topic: Problem with HingeConstraint limits
Replies: 5
Views: 3762

Re: Problem with HingeConstraint limits

Yes, there is a problem when angle limits are close to -PI or PI We added an issue http://code.google.com/p/bullet/issues/detail?id=217 and will fix it in future. As a workaround you could create a dummy static body (without mass and shape) and set hinge limits relative to its frame instead of using...
by rponomarev
Tue Apr 07, 2009 12:12 am
Forum: General Bullet Physics Support and Feedback
Topic: Locked 6DOF constraint is springy
Replies: 8
Views: 14294

Re: Locked 6DOF constraint is springy

If objects are fairly closeby, the simulation should not be springy. In the attached demo 6DOF constraint between static and dynamic objects has all DOF locked and looks stable.

Can you try to keep the static and dynamic object closeby?
Thanks,
Roman
by rponomarev
Thu Apr 02, 2009 10:44 pm
Forum: General Bullet Physics Support and Feedback
Topic: Spring constraints?
Replies: 3
Views: 4729

Re: Spring constraints?

Hello, The current version of Bullet (2.74) does not have spring motors for constraints. We plan to add them in future. However as a workaround you could easily simulate the spring using existing constraint (e.g. slider) and motors Here is an example: class btSliderSpringConstraint : public btSlider...
by rponomarev
Wed Mar 18, 2009 4:02 am
Forum: Release Announcements
Topic: Bullet 2.74 released: constraint visualization
Replies: 11
Views: 88884

Re: Bullet 2.74 released: constraint visualization

Hello,

All constraint drawing functions are based on btIDebugDraw::drawLine() call
so they should work if you have this function implemented

Thanks,
Roman
by rponomarev
Wed Mar 11, 2009 9:04 pm
Forum: General Bullet Physics Support and Feedback
Topic: What unit is setMaxLinMotorForce in?
Replies: 1
Views: 2456

Re: What unit is setMaxLinMotorForce in?

Hello, The definition of the maxLinMotorForce may be a little bit confusing Actually it sets limits for the applied impulse for the constraint solver. To set it in newtons you should use the following formula: slider->setMaxLinMotorForce(maxForceInNewtons * dt * dt); where dt is the simulation time ...
by rponomarev
Wed Mar 04, 2009 8:08 pm
Forum: Applications, Games, Demos or Movies using Bullet
Topic: Robot Simulation
Replies: 2
Views: 4626

Re: Robot Simulation

Hello, You can use the btSliderConstraint with linear motor to simulate a piston. To enable motor add code like pSlider->setPoweredLinMotor(true); // enable the motor pSlider->setMaxLinMotorForce(0.1); // maximum motor force pSlider->setTargetLinMotorVelocity(5.0); // desired velocity You may also l...
by rponomarev
Sat Feb 28, 2009 1:43 am
Forum: General Bullet Physics Support and Feedback
Topic: Moving physic objects with constraints
Replies: 2
Views: 6100

Re: Moving physic objects with constraints

Hello Laurent, Stability of such a system mostly depends on animation of your kinematic objects. Constraint attached to a dynamic body adds several equations to linear system that defines the resulting motion of the body. For example, the 6DOF constraint could add from 0 to 6 equations to the system...
by rponomarev
Fri Feb 20, 2009 6:21 pm
Forum: General Bullet Physics Support and Feedback
Topic: Hinge constraint limits upside-down?
Replies: 7
Views: 9853

Re: Hinge constraint limits upside-down?

Hello Kate,

We plan to add a possibility to choose between reference frames A and B for all joints.
This will work for both linear and angular parts.
Probably we'll release it in version 2.75

Thank you,
Roman
by rponomarev
Thu Feb 19, 2009 8:55 pm
Forum: General Bullet Physics Support and Feedback
Topic: btConeTwistConstraint limits question
Replies: 4
Views: 3370

Re: btConeTwistConstraint limits question

Hello Kate,

Instability of the btConeTwistConstraint when swing limits are zero will be fixed in 2.74
Actually the code was already committed to GoogleCode as of r1628

Thanks,
Roman
by rponomarev
Wed Feb 18, 2009 8:14 pm
Forum: General Bullet Physics Support and Feedback
Topic: Question: How to use motor in btConeTwistConstraint
Replies: 5
Views: 4607

Re: Question: How to use motor in btConeTwistConstraint

Hello, Motor for the btConeTwistConstraint is still the work-in-progress. It is only test implementation for the obsolete constraint solver. You can try it by using #define CONETWIST_USE_OBSOLETE_SOLVER false You may also use the btGeneric6DofConstraint instead, it has all motors implemented Hinge a...
by rponomarev
Wed Feb 18, 2009 7:56 pm
Forum: General Bullet Physics Support and Feedback
Topic: btConeTwistConstraint limits question
Replies: 4
Views: 3370

Re: btConeTwistConstraint limits question

Hello Kate, Twist axis for the btConeTwistConstraint is the X axis. You can see it in the "appConstraintDemo", where the debug drawing of constraint limits is turned on. X axis is red, Y is green and Z is blue. You may also wish to comment out all other constraints in the demo Thanks, Roman