Real-Time Physics Simulation Forum

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...

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 t...

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 "pr...

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

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....

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

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...

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...

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.

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...

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 ...

Thanks!!

Hi Erwin,

that is excellent news!

Ola

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...

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...