Search found 31 matches

by Moose
Mon Jan 13, 2014 2:26 pm
Forum: General Bullet Physics Support and Feedback
Topic: btSliderConstraint
Replies: 9
Views: 3118

btSliderConstraint

Hello everyone, I'm trying to include slider constraints into my bullet project after having successfully included 6dof, ball socket and hinge. With sliders however, I have surprisingly bad results. Basically, each object only ever seems to travel along it's X Axis. I found an old thread in this for...
by Moose
Mon Jan 13, 2014 2:19 pm
Forum: General Bullet Physics Support and Feedback
Topic: Building Bullet 2.81 on Windows 8 (cmake and make errors)
Replies: 2
Views: 2762

Re: Building Bullet 2.81 on Windows 8 (cmake and make errors

I'm not sure if I answer correctly but I answer nonetheless as I build on Windows successfully .-) About the errors concerning GLUT: Don't worry about them. Unless you actually have GLUT in your environment and plan to use it, e.g. for debug output. I get the same errors and just ignore them. Also, ...
by Moose
Thu Jan 09, 2014 2:36 pm
Forum: General Bullet Physics Support and Feedback
Topic: btConeTwistConstraint with friction?
Replies: 1
Views: 2027

Re: btConeTwistConstraint with friction?

A semi-solution here: It appears to be possible to emulate a ball socket constraint using a generic 6dof constraint. With this, you can activate the 3 angular motors and achieve the desired effect. The constraint is quite unstable though. Gravity lets the objects slowly fall. You have to crank up it...
by Moose
Wed Jan 08, 2014 2:26 pm
Forum: General Bullet Physics Support and Feedback
Topic: btConeTwistConstraint with friction?
Replies: 1
Views: 2027

btConeTwistConstraint with friction?

Hello, On another occasion I have simulated rotation friction on a hinge constraint by using the angular motor with target speed 0. Which works OK. Now my question is, is there a similar trick to emulate friction on a cone twist constraint as well? I tried the motor but it requires a target rotation...
by Moose
Fri Nov 29, 2013 12:22 pm
Forum: General Bullet Physics Support and Feedback
Topic: Constraint range
Replies: 3
Views: 1740

Re: Constraint range

Thanks for the clarification. I understand this is all stuff that is supposed to be handled in the simulation substep handler. So far I only extract collision information in there. Looks like there's way more to be done. I'll look into it. BTW, maybe someone can point me to a good starting point? Li...
by Moose
Fri Nov 29, 2013 9:53 am
Forum: General Bullet Physics Support and Feedback
Topic: Hinge Constraint with friction
Replies: 10
Views: 5751

Re: Hinge Constraint with friction

Most certainly sounds like you have too few iterations and too large a time step. Try something like 500 iterations at 1/500 maximum step size (don't forget to take into account the maxSubStep, should be high enough that frame-rate drops won't mess with physics, unless of course you want the door t...
by Moose
Thu Nov 28, 2013 1:09 pm
Forum: General Bullet Physics Support and Feedback
Topic: Hinge Constraint with friction
Replies: 10
Views: 5751

Re: Hinge Constraint with friction

Well, there's limits as to what I can do here because we actually expose many of these values to the user. The system we are building here is like a physical world building blocks like things. The user can import meshes into the system and then freely set the mass of each object. The local inertia v...
by Moose
Thu Nov 28, 2013 10:33 am
Forum: General Bullet Physics Support and Feedback
Topic: Hinge Constraint with friction
Replies: 10
Views: 5751

Re: Hinge Constraint with friction

There's one more thing that puzzles me about that hinge. It allows for an amazing amount of movement of the hinge axis. Considering a door example, if I have a dynamic object push the door open it will do so, but the actual door will wobble in it's hinge quite a bit. From visual judgement I would sa...
by Moose
Thu Nov 28, 2013 8:53 am
Forum: General Bullet Physics Support and Feedback
Topic: Constraint range
Replies: 3
Views: 1740

Re: Constraint range

Right, I couldn't find an answer to all the questions by myself but in case anyone is interested I have a few things. There seems to be no generic way to solve this. By taking the ConstraintDemo examples and applying that to my own use case I found a way to at least make the constraint "weaker" so i...
by Moose
Wed Nov 27, 2013 1:08 pm
Forum: General Bullet Physics Support and Feedback
Topic: Hinge Constraint with friction
Replies: 10
Views: 5751

Re: Hinge Constraint with friction

A little update here. I have tried all sorts of iteration limits for this now an I cannot see any effect at all. So I guess it's huge motor impulse for now.

Thanks,
Moose
by Moose
Wed Nov 27, 2013 8:02 am
Forum: General Bullet Physics Support and Feedback
Topic: Constraint range
Replies: 3
Views: 1740

Constraint range

Hello, I am in the final stages of a bullet based project about integrating bullet into a large commercial visualizations system. It has been challenging, interesting and also a lot of fun to see things moving in a natural like fashion. Much like the ConstraintDemo we are using 6dof generic constrai...
by Moose
Wed Nov 27, 2013 7:48 am
Forum: General Bullet Physics Support and Feedback
Topic: Hinge Constraint with friction
Replies: 10
Views: 5751

Re: Hinge Constraint with friction

You are saying that my solution is not the preferred (as in right) way?
I have tried to set the iterations to 50 which had no effect. I'm gonna try 200 and see what it does.

About direct solvers, I don't know what that is. Would you care to elaborate please?

Thanks,

Moose
by Moose
Tue Nov 26, 2013 1:12 pm
Forum: General Bullet Physics Support and Feedback
Topic: Small cmake change request
Replies: 3
Views: 1653

Re: Small cmake change request

I just stumbled over the same issue, replacing 2.81 by 2.82 here.
You should use <bullet_project_name>_SOURCE_DIR rather than CMAKE_SOURCE_DIR, that's for sure.
by Moose
Tue Nov 26, 2013 12:56 pm
Forum: General Bullet Physics Support and Feedback
Topic: Hinge Constraint with friction
Replies: 10
Views: 5751

Re: Hinge Constraint with friction

Flix,

thanks for your response. As it so happens, you were right. I sort of figured that out trying wild combinations at the same time. If I set the max impulse very high, it has the desired effect. Like that:

hinge_constraint->enableAngularMotor(true, 0 , 100000.0);

Thanks for the help.

Moose
by Moose
Tue Nov 26, 2013 10:28 am
Forum: General Bullet Physics Support and Feedback
Topic: Hinge Constraint with friction
Replies: 10
Views: 5751

Hinge Constraint with friction

Hello, I need a hinge constraint with friction to simulate a certain resistance when a user interacts with an object. Now in this forum I read I can use an angular motor like this: hinge_constraint->enableAngularMotor(true, 0.0, 0.02); I understand this is to create a motor with a target velocity of...