Search found 456 matches

by Flix
Mon Feb 01, 2016 12:52 pm
Forum: General Bullet Physics Support and Feedback
Topic: Slider properties
Replies: 15
Views: 6812

Re: Slider properties

It might be the usual problem with mass differences: try to increase the local inertia of the two bodies (or of the dynamic one if one is static) of a factor of 100 -> 10000 or so and see if something changes. Another approach would be to increase the number of step of the constraint (or the number ...
by Flix
Sat Jan 30, 2016 12:13 pm
Forum: General Bullet Physics Support and Feedback
Topic: addRigidBody or addCollisionObject?
Replies: 2
Views: 2515

Re: addRigidBody or addCollisionObject?

Just wondering if there's any difference 1) Memory impact: the btRigidBody class is bigger, so that if you use hundreds of static bodies it can make a big difference. 2) Constraints: they accept only btRigidBodies: so you can't use btCollisionObjects at all (AFAIK). 3) Setup: if you use btCollision...
by Flix
Thu Jan 21, 2016 3:19 pm
Forum: General Bullet Physics Support and Feedback
Topic: Beginner Issues with ConvexHullShape
Replies: 2
Views: 2084

Re: Beginner Issues with ConvexHullShape

//currently just a vector with the 8 corners of a 2x2x2 cube (0,0,0) (2,0,0) etc. (0,0,0) is the center of mass. You must choose vertices like (-1,0,0) (1,0,0) etc. P.S. People keeps asking the same things over and over again in this forum. It's not the first time I answer to questions like this on...
by Flix
Thu Oct 29, 2015 2:49 pm
Forum: General Bullet Physics Support and Feedback
Topic: Possible Bug in btShapeHull
Replies: 2
Views: 1801

Re: Possible Bug in btShapeHull

Setting the margin parameter to zero won't work, because that parameter is actually ignored. You actually need to call convexHullShape.setMargin(0); before creating the btShapeHull. Good to know that this works (I assume that after the processing you can still reassign your previous collision margi...
by Flix
Thu Oct 22, 2015 6:23 pm
Forum: General Bullet Physics Support and Feedback
Topic: btKinematicCharacterController and recoverFromPenetration
Replies: 5
Views: 2287

Re: btKinematicCharacterController and recoverFromPenetratio

Not sure if this is helpful or not, but a long time ago, I found a similar problem and posted a possible solution here (please read only my last post): http://bulletphysics.org/Bullet/phpBB3/viewtopic.php?f=9&t=9671&p=32566#p32566 . Basically, AFAICR, I needed to put my controller outside the aabb o...
by Flix
Tue Sep 29, 2015 5:49 pm
Forum: General Bullet Physics Support and Feedback
Topic: Some questions about serialization
Replies: 6
Views: 2882

Re: Some questions about serialization

It seems that the code above is loading the same thing twice, two different ways, first via bvh, then via getCollisionShapeByIndex. Why is it doing that? I'm guessing that I should only use one method, but really I have no idea. Is there any documentation for this? Not sure if I'm right, but I reme...
by Flix
Wed Sep 09, 2015 12:46 pm
Forum: General Bullet Physics Support and Feedback
Topic: Proper object for light barrier or other sensors:ghost/rigid
Replies: 2
Views: 1457

Re: Proper object for light barrier or other sensors:ghost/r

There is anther type of ghost object you can use for non aabb collision detection. Please search the wiki or the ghost object demo I posted in this forum long ago. However for non moving bodies, an alternative is using a static or kinematic body with no collision response, and process the manifolds ...
by Flix
Wed Sep 09, 2015 12:33 pm
Forum: General Bullet Physics Support and Feedback
Topic: Detecting if the character is on ground
Replies: 4
Views: 2647

Re: Detecting if the character is on ground

Your ghost object can show you all the contact points. You can filter them and apply some logic to detect when a point is at the bottom of your sphere.

Edit: you can probably solve the problem simply by using a sphere with a smaller radius, so that it touches only the bottom of the capsule.
by Flix
Sat May 23, 2015 7:10 am
Forum: General Bullet Physics Support and Feedback
Topic: Big problem with kinematic-dynamic constraints
Replies: 5
Views: 3248

Re: Big problem with kinematic-dynamic constraints

First of all: I've never tried using constraints between kinematic and dynamic bodies. Anyway in the past I've successfully "chained" dynamic rigid bodies solving the problem of occasional "gaps" between them simply by "faking" the graphics. This is easier to do if your hair braid is made by a strip...
by Flix
Mon May 11, 2015 6:50 am
Forum: General Bullet Physics Support and Feedback
Topic: New 6DOF Spring2 constraint spring limiting issue. Bug?
Replies: 9
Views: 6247

Re: New 6DOF Spring2 constraint spring limiting issue. Bug?

I know nothing about the internals of this new constraint (and of contraints in general), but, based on the equations you wrote, the correction: ks = BT_ONE / dt / dt / btScalar(16.0) * m; // Or: ks = BT_ONE*m/(dt*dt*btScalar(16.0)); makes sense. BTW: Incidentally, in this bullet3 issue, https://git...
by Flix
Mon May 11, 2015 6:25 am
Forum: General Bullet Physics Support and Feedback
Topic: Change position of a convex hull after creation
Replies: 5
Views: 2346

Re: Change position of a convex hull after creation

Is there a simple way to center the pivot/axis of convex hull? Do you mean its center of mass ? Well I'd do that before feeding the vertices to the btConvexHullShape (although making a helper method that does that inside the btConvexHullShape itself shouldn't be too difficult). The center of a (tri...
by Flix
Sun May 03, 2015 4:54 pm
Forum: General Bullet Physics Support and Feedback
Topic: sphere not bouncing ( cant add restitution )
Replies: 1
Views: 1572

Re: sphere not bouncing ( cant add restitution )

I'd try the following: 1) Set a higher restitution to to the static ground body too (by default the combined restitution is the the product of the restitutions of the two bodies). [I personally use a box shape for the static floor, but that shouldn't make any difference AFAIK]. 2) Reduce the sphere ...
by Flix
Sat Apr 18, 2015 6:29 am
Forum: General Bullet Physics Support and Feedback
Topic: btCompoundShape: collision detection problem! :?:
Replies: 10
Views: 4367

Re: btCompoundShape: collision detection problem! :?:

When I do "compoundShape->addChildShape(relTransform, childShape);" inside a "for" loop in c++, it will remain valid within that loop, not outside! If I remove that for loop and do the "addChildShape" fuction inside the main block it will work well. Well, this is probably a problem inside your code...
by Flix
Fri Apr 17, 2015 11:06 am
Forum: General Bullet Physics Support and Feedback
Topic: btCompoundShape: collision detection problem! :?:
Replies: 10
Views: 4367

Re: btCompoundShape: collision detection problem! :?:

However, in the case you apply a central force in horizontal direction, it will goes for ever! without "feeling" the vertical childshapes of the empty box. Another try (but I'm not very confident now): Can it be a problem with the physic world bounds ? Are you using a btDbvhBroadphase ? Otherwise t...
by Flix
Fri Apr 17, 2015 10:44 am
Forum: General Bullet Physics Support and Feedback
Topic: btCompoundShape: collision detection problem! :?:
Replies: 10
Views: 4367

Re: btCompoundShape: collision detection problem! :?:

1) the first suggestion for my case is not possible, because I have another compound shape which is dynamic object. Not a big issue (you can just reuse the child shapes of the dynamic object, so that you have 5 new static bodies made with them, even if adding 5 new static box shapes shouldn't be a ...