Search found 48 matches
- Mon Feb 28, 2011 10:34 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: Ogre + Bullet simple collision detection
- Replies: 2
- Views: 3719
Re: Ogre + Bullet simple collision detection
Um, in the transform.setOrigin calls you have two .x's
- Thu Sep 23, 2010 4:46 am
- Forum: General Bullet Physics Support and Feedback
- Topic: Changing gravity depending on position.
- Replies: 3
- Views: 4447
Re: Changing gravity depending on position.
How about modifying btRigidBody::applyGravity() in Bullet itself, and submitting a patch? Perhaps with #ifdefs so the default is constant gravity like it is now.
- Tue Sep 21, 2010 12:08 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: Limit softbody deformations
- Replies: 10
- Views: 14252
Re: Limit softbody deformations
hey ca$per - FWIW I'm doing something very similar with softbody sails on a small sailing boat , and I've hit the same problems. 1. rigid bodies penetrate soft bodies (ie the collision response is not strong enough) 2. soft bodies are way too stretchy, like very thin rubber, regardless of the materi...
- Tue Aug 03, 2010 2:43 am
- Forum: General Bullet Physics Support and Feedback
- Topic: applytorque about specific point?
- Replies: 6
- Views: 6474
Re: applytorque about specific point?
Thought I'd just post my code for doing that ... btTransform frameInA; frameInA.setIdentity(); frameInA.setOrigin(position_of_B_in_A_local_coordinates); // attachment point for B is at its center of gravity btTransform frameInB; frameInB.setIdentity(); btGeneric6DofConstraint* pConstraint = new btGe...
- Wed Jul 28, 2010 11:38 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: Path trajectory
- Replies: 2
- Views: 3620
Re: Path trajectory
If the only force acting on the cannon ball is gravity (ie no air resistance), the trajectory will be a parabola which you can work out the trajectory mathematically - google "balistic trajectory".
Whether that matches the trajectory Bullet comes up with is another thing entirely...
Whether that matches the trajectory Bullet comes up with is another thing entirely...
- Wed Jul 28, 2010 11:29 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: How to check when an object is stationary
- Replies: 2
- Views: 3236
Re: How to check when an object is stationary
btCollisionObject::isActive() will tell you if something's been put to sleep...
- Wed Jul 28, 2010 11:26 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: btRigidBody::upcast() is a downcast?
- Replies: 6
- Views: 7155
Re: btRigidBody::upcast() is a downcast?
yup, it's the wrong way round. But it kind of makes sense as opposed to going "up" towards the "base"
- Thu Jul 22, 2010 2:46 am
- Forum: Research and development discussion about Collision Detection and Physics Simulation
- Topic: Volume of the Intersection Between a Sphere and a Cube?
- Replies: 3
- Views: 7018
Re: Volume of the Intersection Between a Sphere and a Cube?
Doing boolean operations on 3D shapes like that is known as "constructive solid geometry" (see the pic http://en.wikipedia.org/wiki/Constructive_solid_geometry ). I've not used any of them myself, but there are a few CSG libraries aboutyou could look at, like Carve (http://carve-csg.com/) ...
- Wed Jul 21, 2010 2:10 am
- Forum: General Bullet Physics Support and Feedback
- Topic: Documentation
- Replies: 2
- Views: 3038
Re: Documentation
It's a known problem - see the sticky above and issue #42 . There are plenty of people willing to write some docs (myself included, for the basic stuff), but it needs someone with SVN commit access to really make it happen. In the mean time, you're best off reading the source code. It's well written...
- Mon Jul 19, 2010 9:21 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: Collision shape does not rotate
- Replies: 3
- Views: 4131
Re: Collision shape does not rotate
Also, that's not how motion states work. The documentation doesn't explain it terribly well, but basically the get and set functions are called by Bullet to update your objects. getWorldTransform is called by Bullet to query the position & orientation of an object (for normal non-kinematic bodie...
- Sun Jul 18, 2010 7:55 am
- Forum: General Bullet Physics Support and Feedback
- Topic: trajectory of a missile
- Replies: 1
- Views: 3006
Re: trajectory of a missile
I'd guess a missile's nose turns not because of gravity, but because the fins at the back apply a force if the missile's not flying straight along it's axis (like an arrow). Calculate the missile's velocity in local coordinates, and add a force to the tail which acts against the x & y components...
- Wed Jul 14, 2010 5:00 am
- Forum: General Bullet Physics Support and Feedback
- Topic: Bullet wiki or documentation repo?
- Replies: 67
- Views: 105767
Re: Bullet wiki or documentation repo?
Yup, agreed. Bullet is severely let down by it's lack of (inline) documentation. The class and variable naming is good so you can usually work things out by reading the code (apart from the softbody code, which is let down by lack of documentation and one letter variable names :? ) It's a shame, 'co...
- Tue Jul 13, 2010 2:43 am
- Forum: Applications, Games, Demos or Movies using Bullet
- Topic: Sailing demo
- Replies: 0
- Views: 5103
Sailing demo
http://www.youtube.com/watch?v=9t-v1rh9Dhg A boat with a softbody clothg sail being blown downwind. The rudder is rigged to counteract the torque from the sail (more or less). The heavy keel keeps the boat from capsizing, and also resists sideways movement by applying drag forces. Next - add proper ...
- Thu Jul 08, 2010 10:38 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: non physical behaviour of rotation
- Replies: 9
- Views: 8183
Re: non physical behaviour of rotation
or even just
sorry, I was thinking in Ogre terms, which keeps the orientation & position separately
Code: Select all
btVector3 anchorPos = d_object->getWorldTransform() * d_localAnchor
- Thu Jul 08, 2010 8:54 am
- Forum: General Bullet Physics Support and Feedback
- Topic: non physical behaviour of rotation
- Replies: 9
- Views: 8183
Re: non physical behaviour of rotation
another thing you could try is an alternative way of getting the anchor position in world space, like this btVector3 anchorPos = (d_object->getWorldTransform().getBasis() * d_localAnchor) + d_object->getCenterOfMassPosition(); .. although the way you're explicitly applying the orientation rotation s...