Search found 597 matches

by drleviathan
Wed Apr 01, 2020 7:49 pm
Forum: General Bullet Physics Support and Feedback
Topic: AddCentralImpulse() Not Working Properly(Unity3d)
Replies: 2
Views: 73

Re: AddCentralImpulse() Not Working Properly(Unity3d)

My guess is the RigidBody is going inactive after the default 2 seconds. If you first activate (probably cueBall.RigidBody.Activate() or something like that) before applying the impulse it might work. Bullet will deactivate dynamic RigidBodies whose velocities are below some thresholds for longer th...
by drleviathan
Mon Mar 30, 2020 3:20 pm
Forum: General Bullet Physics Support and Feedback
Topic: btIDebugDraw implementation isn't drawing anything
Replies: 2
Views: 89

Re: btIDebugDraw implementation isn't drawing anything

Check the implementation of btCollisionWorld::debugDrawObject() . AFAICT there is no support there for rendering btBvhTriangleMeshShape . That code has a switch on the ShapeType and in the default case it only handles convex shapes. Try using convex shapes, or override the debugDrawObject() method a...
by drleviathan
Fri Mar 27, 2020 2:53 pm
Forum: General Bullet Physics Support and Feedback
Topic: Object going past Hinge Constraint Limits
Replies: 3
Views: 192

Re: Object going past Hinge Constraint Limits

Typically a constraint connects two objects: objectA and objectB. The local-frame transform of the constraint pivot needs to be defined in the local-frame of each object and the constraint will work hard to align those two local-frame pivots on top of each other in the world-frame. One way to think ...
by drleviathan
Fri Mar 27, 2020 2:06 am
Forum: General Bullet Physics Support and Feedback
Topic: Object going past Hinge Constraint Limits
Replies: 3
Views: 192

Re: Object going past Hinge Constraint Limits

What size of fixed substep are you using? Default is 1/60 of a second, and if your flipper is rotating too fast then it could probably "tunnel" past the limit by one whole substep's worth of distance. If your substep is long then try using a smaller substep. The center of mass (COM) of the flipper i...
by drleviathan
Mon Mar 23, 2020 3:19 pm
Forum: General Bullet Physics Support and Feedback
Topic: How to install for someone who is completely new to this
Replies: 1
Views: 150

Re: How to install for someone who is completely new to this

If you examine build_visual_studio_without_pybullet_vr.bat you'll see this: cd build3 premake5 --targetdir="../bin" vs2010 start vs2010 Maybe try editing that script to use your installed version of Visual Studio to see what happens. Note: that script uses premake5 . There is also a CMakeLists.txt f...
by drleviathan
Mon Mar 23, 2020 2:18 pm
Forum: General Bullet Physics Support and Feedback
Topic: Fixed Contraint
Replies: 3
Views: 154

Re: Fixed Contraint

To make a concave dynamic object you would use btCompoundShape , which has convex sub-shapes. In your case: five subshapes for the box's walls, each a btBoxShape . In the btCompoundShape 's local frame <0,0,0> is its center of mass (COM). So you would give each sub-shape a local offset relative to t...
by drleviathan
Sun Mar 22, 2020 4:41 pm
Forum: General Bullet Physics Support and Feedback
Topic: Fixed Contraint
Replies: 3
Views: 154

Re: Fixed Contraint

If your box walls should never move then make them static instead of dynamic. If you set an object's mass to zero before adding to the world then it will be static by default.
by drleviathan
Sun Mar 22, 2020 4:39 pm
Forum: General Bullet Physics Support and Feedback
Topic: Gravitational acceleration is decreasing
Replies: 2
Views: 182

Re: Gravitational acceleration is decreasing

Read this thread. TL;DR zero your rocket's damping.
by drleviathan
Thu Mar 12, 2020 8:27 pm
Forum: General Bullet Physics Support and Feedback
Topic: windows & linux build of application & bullet behave very differently, but why
Replies: 6
Views: 313

Re: windows & linux build of application & bullet behave very differently, but why

AFAIK this isn't a common problem on windows for other uses so my intuition tells me: if this is a Real Bug then you've found an obscure recipe for it. Which makes me wonder: what are you doing that is odd or uncommon? I don't have many ideas as to what it would be without more information but here ...
by drleviathan
Thu Mar 12, 2020 3:13 pm
Forum: General Bullet Physics Support and Feedback
Topic: windows & linux build of application & bullet behave very differently, but why
Replies: 6
Views: 313

Re: windows & linux build of application & bullet behave very differently, but why

I wonder if you're getting NaN injection. When one of the objects in the simulation gets NaN in one of its values then NaN can propagate to other objects and cause very strange and varied failures. These things happen because: NaN + number = NaN and all comparisons against NaN evaluate to false henc...
by drleviathan
Thu Mar 12, 2020 3:06 pm
Forum: General Bullet Physics Support and Feedback
Topic: Large & Small Collision Shapes and Large Mass Ratios
Replies: 1
Views: 173

Re: Large & Small Collision Shapes and Large Mass Ratios

If you have small satellites interacting with large planets using a weak coupling like gravity then you should be fine. However, if you were making dynamic piles of planets crushing small satellites between them using hard RigidBody collisions then you would have problems. Similarly, a few small shi...
by drleviathan
Wed Mar 11, 2020 3:17 pm
Forum: General Bullet Physics Support and Feedback
Topic: Understanding btGeneric6DofConstraint
Replies: 3
Views: 401

Re: Understanding btGeneric6DofConstraint

Yeah, I've always been daunted by the complexity of the btGeneric6DofConstraint parameters. I dunno the answers to your questions. Maybe someone else does.
by drleviathan
Mon Mar 09, 2020 4:39 pm
Forum: General Bullet Physics Support and Feedback
Topic: help needed:rigid body Kinematic Collisions penetrate
Replies: 3
Views: 293

Re: help needed:rigid body Kinematic Collisions penetrate

One way to do it would be to derive your own KinematicMotionState from btMotionState and use that instead. Of course, you'd have to set the velocities to what you'd like them to be and make sure the kinematic object is active. Note: I copied and then modified this from working code I copied from Bul...
by drleviathan
Sat Mar 07, 2020 5:19 pm
Forum: General Bullet Physics Support and Feedback
Topic: Understanding btGeneric6DofConstraint
Replies: 3
Views: 401

Re: Understanding btGeneric6DofConstraint

I believe the transform parameters of the btGeneric6DofConstriant represent the offset to the "pivot" of the constraint in each body's local-frame. In the simplest 6Dof configuration where all 6 degrees are fully constrained (e.g. acting like a btFixedConstraint )... in the constraint solver math wi...
by drleviathan
Sat Mar 07, 2020 4:57 pm
Forum: General Bullet Physics Support and Feedback
Topic: How to balance an object
Replies: 1
Views: 226

Re: How to balance an object

Since the rectangle falls over I assume it is a dynamic box. You say you would like it to "stand still" while it is being moved. I assume you mean you want it to remain standing up while it is moved. If you push a dynamic box at the center while it is resting on a floor then I would expect friction ...