Search found 169 matches

by ola
Mon Mar 01, 2010 11:13 pm
Forum: General Bullet Physics Support and Feedback
Topic: The clearForces in btDiscreteDynamicsWorld::stepSimulation
Replies: 1
Views: 1293

Re: The clearForces in btDiscreteDynamicsWorld::stepSimulation

I think you can use a pre-tick callback, see this article: (there is a preTick = true argument) http://bulletphysics.org/mediawiki-1.5.8/index.php/Simulation_Tick_Callbacks You can add both a pre-tick callback function and a post-tick callback. The actual code executing this is found in btDiscreteDy...
by ola
Thu Feb 25, 2010 11:32 am
Forum: General Bullet Physics Support and Feedback
Topic: Right to use Double Precision bullet
Replies: 12
Views: 6527

Re: Right to use Double Precision bullet

There is an option in Bullet's CMakeLists.txt file (the one in the Bullet root folder). find OPTION(USE_DOUBLE_PRECISION "Use double precision" OFF) and change it to ON, like OPTION(USE_DOUBLE_PRECISION "Use double precision" ON) Seems to work fine for me here. After you change the options, I found ...
by ola
Wed Feb 10, 2010 1:54 pm
Forum: General Bullet Physics Support and Feedback
Topic: Issue with convexSweepTest() not reporting hits
Replies: 8
Views: 4379

Re: Issue with convexSweepTest() not reporting hits

An easy to use API query will be added for discrete collision detection, with a first beta release of 2.76 later this month. Using a ghost shape should be fine too, there should be no need for update cycles. Hi, just wondered if this particular feature has been added yet? I need to do some "probing...
by ola
Tue Feb 02, 2010 5:53 pm
Forum: General Bullet Physics Support and Feedback
Topic: Continous response to change in gravity
Replies: 2
Views: 1098

Re: Continous response to change in gravity

You can disable the deactivation for a rigid body, see this post
http://bulletphysics.org/Bullet/phpBB3/ ... ion#p15454

Also, you can use body->activate() to wake it up if it has fallen asleep.

Cheers,
Ola
by ola
Tue Jan 19, 2010 9:17 am
Forum: General Bullet Physics Support and Feedback
Topic: Possable applications.
Replies: 4
Views: 1636

Re: Possable applications.

The double precision re-compile, is that simply a compile time variable change? Is there information about this on the Wiki? You need to make sure that BT_USE_DOUBLE_PRECISION is defined throughout the code. You can add a #define BT_USE_DOUBLE_PRECISION at the top of btScalar.h, which should do it....
by ola
Mon Jan 18, 2010 10:02 pm
Forum: General Bullet Physics Support and Feedback
Topic: Possable applications.
Replies: 4
Views: 1636

Re: Possable applications.

For a geocentric earth you can compile Bullet to use double precision numbers, and configure it to use the btDvtBroadphase. I do this in several projects that use a globe model with a geocentric coordinate system and it's working very well.

Best regards,
Ola
by ola
Wed Jan 06, 2010 3:39 pm
Forum: General Bullet Physics Support and Feedback
Topic: using btIDebugDraw, some functions are never used?
Replies: 0
Views: 1389

using btIDebugDraw, some functions are never used?

I've made my own debug drawer class that inherits btIDebugDraw, and registered it. It works OK, but everything is drawn in wireframe using the drawLine function. By inspecting the code in btCollisionWorld::debugDrawWorld(), I see that most functions in btIDebugDraw are never used. For example, btCol...
by ola
Mon Jan 04, 2010 10:05 pm
Forum: General Bullet Physics Support and Feedback
Topic: New issue with gContactAddedCallback in Bullet 2.75
Replies: 40
Views: 12189

Re: New issue with gContactAddedCallback in Bullet 2.75

But having a compound inside another compound is pretty meaningless Just to comment on that, I sometimes find this quite useful. I use it when simulating objects where the centre of gravity moves. For example, an aircraft model using a compound of several convex hulls (wings, fuselage, etc). When u...
by ola
Wed Dec 16, 2009 2:43 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Convex decomposition, is this a wrong way of thinking?
Replies: 8
Views: 2925

Re: Convex decomposition, is this a wrong way of thinking?

It is the one one from John Ratcliff. I just found this: http://codesuppository.blogspot.com/200 ... y-now.html
Maybe that version is a bit more recent than the one provided with Bullet, I haven't compared them.
by ola
Tue Dec 15, 2009 11:11 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Convex decomposition, is this a wrong way of thinking?
Replies: 8
Views: 2925

Re: Convex decomposition, is this a wrong way of thinking?

There is a convex decomposition library provided with Bullet, you can find it in the Extras/ConvexDecomposition directory. It is not depending on Bullet. I've used it some times and it's OK for my needs. At least you won't have to implement it all from scratch if you just want to do some testing. Ch...
by ola
Mon Dec 14, 2009 1:15 pm
Forum: General Bullet Physics Support and Feedback
Topic: Bounding Volume
Replies: 5
Views: 3157

Re: Bounding Volume

I'm not sure if I understand your original question correctly. If you want to do a raycast against some bounding volumes defined by you, then you can just create a rigid body with a collision shape of your choice to represent that volume. I think what you call bounding volume is in fact a collision ...
by ola
Thu Dec 10, 2009 11:21 am
Forum: General Bullet Physics Support and Feedback
Topic: Add "virtual" to two btRigidBody methods?
Replies: 2
Views: 1433

Re: Add "virtual" to two btRigidBody methods?

Hi Erwin,

that is excellent news! :-)

Ola
by ola
Wed Dec 09, 2009 2:40 pm
Forum: General Bullet Physics Support and Feedback
Topic: Questions about btDbvt and frustum/occlusion culling
Replies: 2
Views: 3372

Questions about btDbvt and frustum/occlusion culling

We're looking into using the btDbvt class for frustum culling and also potentially occlusion culling. I have looked into the BulletSAPCompleteBoxPruningTest code to get an idea of how to do it. Here are a few questions I'm left with. In general, is this kind of frustum culling some of the fastest me...
by ola
Wed Dec 09, 2009 12:44 pm
Forum: General Bullet Physics Support and Feedback
Topic: Detect collision between swept kinematic objects?
Replies: 1
Views: 1489

Detect collision between swept kinematic objects?

I have some kinematic objects, which are moved around according to recorded data (position, orientation) each frame. The velocities can be high, so tunneling could occur, if it was a simulation (it's playback only). Now, I need to analyze such a recording, to see if any collisions happened. Note tha...