Search found 169 matches

by ola
Mon Oct 31, 2011 3:09 pm
Forum: General Bullet Physics Support and Feedback
Topic: btDbvt::collideOCL (and KDOP) documentation
Replies: 8
Views: 10625

Re: btDbvt::collideOCL (and KDOP) documentation

Thank you very much, Flix :-) I got the frustum culling to work now, after some time of trial and error. The OCL sorting works just fine. I also tried to use the occlusion culling code from the test framework. It seems it's assuming a fixed camera with no rotation, as the buffer is not paying any at...
by ola
Fri Oct 28, 2011 2:45 pm
Forum: General Bullet Physics Support and Feedback
Topic: btDbvt::collideOCL (and KDOP) documentation
Replies: 8
Views: 10625

btDbvt::collideOCL (and KDOP) documentation

Hi all, I am trying to make sense of the frustum culling feature of btDbvt (the collideOCL and collideKDOP functions). I am looking at the single implementation I can find using it in the BulletSAPCompleteBoxPruningTest.cpp file (found in the Extras/CDTestFramework) as reference but as I read elsewh...
by ola
Tue Oct 05, 2010 2:43 pm
Forum: General Bullet Physics Support and Feedback
Topic: Large triangles
Replies: 2
Views: 1143

Re: Large triangles

I can at least confirm that SRTM-based meshes work very well in double precision mode. So if single precision doesn't work, you can try that.

Best regards,
Ola
by ola
Tue Aug 24, 2010 12:35 pm
Forum: General Bullet Physics Support and Feedback
Topic: Motor doesn't wake up rigid body
Replies: 6
Views: 4885

Re: Motor doesn't wake up rigid body

I wasn't able to see from your video if the rigid body really goes to sleep. Maybe you can implement the color of the body to change as a function of the activation state, like in the Bullet demos? In my code I disable deactivation using body->setActivationState(DISABLE_DEACTIVATION); Not really sol...
by ola
Tue Aug 24, 2010 7:58 am
Forum: General Bullet Physics Support and Feedback
Topic: kinematic aeroplane?
Replies: 2
Views: 1893

Re: kinematic aeroplane?

Hi, if you use the kinematic objects, it's still possible to write code to handle all kinds of collisions and how to handle them. But you will soon see that it can be complicated to handle all the various cases that will come up. The kinematic character controller is an example of this, so you shoul...
by ola
Mon Aug 02, 2010 1:40 pm
Forum: General Bullet Physics Support and Feedback
Topic: applytorque about specific point?
Replies: 6
Views: 1973

Re: applytorque about specific point?

Torque in itself cannot be applied to a specific point on a body. This is not a limitation in Bullet but rather just how the concept "torque" is defined. The rigid body will always rotate around its center of gravity which is fixed in (0,0,0). So to move the center of gravity in Bullet you'll have t...
by ola
Tue May 04, 2010 8:20 am
Forum: General Bullet Physics Support and Feedback
Topic: Collision detection in a large world
Replies: 3
Views: 1242

Re: Collision detection in a large world

Are you running Bullet compiled with the double-precision option? It's necessary for such large coordinates.
by ola
Sun Apr 18, 2010 9:59 pm
Forum: General Bullet Physics Support and Feedback
Topic: ClosestNotUsRayResultCallback (code)
Replies: 2
Views: 1238

Re: ClosestNotUsRayResultCallback (code)

You can submit it to the issue tracker:
http://code.google.com/p/bullet/issues/list

Cheers,
Ola
by ola
Fri Apr 16, 2010 1:35 pm
Forum: General Bullet Physics Support and Feedback
Topic: Shape Defined Via Equation?
Replies: 12
Views: 2886

Re: Shape Defined Via Equation?

Really nice!!! I think it would help a bit if you try to make the triangles single-sided. Then your objects will be moved out to the front side as soon as they touch a triangle, which sortof makes the ground a bit "thicker". It was discussed in this thread earlier: http://bulletphysics.org/Bullet/ph...
by ola
Mon Apr 12, 2010 5:57 pm
Forum: General Bullet Physics Support and Feedback
Topic: Simple newtonian simulations giving wrong results
Replies: 4
Views: 1520

Re: Simple newtonian simulations giving wrong results

Since your problem sounds to be 2-dimensional, I think you should simplify things a bit to have more control over the results. You can constrain linear movement to two linear axes and one rotational axis, disable the gravity, and then calculate your own friction forces. See the Box2d demo for some e...
by ola
Mon Apr 12, 2010 1:19 pm
Forum: General Bullet Physics Support and Feedback
Topic: virtual character instantiation
Replies: 2
Views: 933

Re: virtual character instantiation

You can share collision shapes between several collision objects/rigid bodies, and this is even recommended when possible. So you can do this. Collision objects (and rigid bodies) however cannot be shared as they contain the actual position and orientation of the object, among lots of things. Cheers...
by ola
Mon Apr 12, 2010 9:22 am
Forum: General Bullet Physics Support and Feedback
Topic: PD Controller
Replies: 1
Views: 912

Re: PD Controller

Some of the constraints in Bullets have something called "motors", that can be used for this. Take a look at the DynamicControlDemo, it uses this to animate a spider-like contraption.

Cheers,
Ola
by ola
Sun Apr 11, 2010 9:47 am
Forum: General Bullet Physics Support and Feedback
Topic: Raycast vehicle tilts when turning right or left
Replies: 5
Views: 2793

Re: Raycast vehicle tilts when turning right or left

Thank You! But it does not help. I made it localTrans.setOrigin(btVector3(0,0,2.0f)); localTrans.setOrigin(btVector3(0,0,5.0f)); localTrans.setOrigin(btVector3(0,0,10.0f)); It always tilts as before. The z-axis is positive downwards, so you need to try 0.0 or a negative value. The 1.0 value sets th...
by ola
Fri Apr 09, 2010 6:37 pm
Forum: General Bullet Physics Support and Feedback
Topic: Raycast vehicle tilts when turning right or left
Replies: 5
Views: 2793

Re: Raycast vehicle tilts when turning right or left

Your center of gravity is set too low (it's below the ground). Move it up and you will get the effect you want. In the vehicle demo VehicleDemo.cpp, this happens on line 310: //localTrans effectively shifts the center of mass with respect to the chassis localTrans.setOrigin(btVector3(0,0,1)); Cheers...
by ola
Thu Apr 08, 2010 8:44 am
Forum: General Bullet Physics Support and Feedback
Topic: Cannot slide correctly against btBvhTriangleMeshShape
Replies: 1
Views: 866

Re: Cannot slide correctly against btBvhTriangleMeshShape

I have made a similar character controller, pushing a capsule around. I almost only use the btBvhTriangleMeshShape for the environment but haven't had any of the problems you describe. Maybe we can figure out what we are doing differently... here are some quick ideas: - I have set friction and resti...