Real-Time Physics Simulation Forum

Um, in the transform.setOrigin calls you have two .x's

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.

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...

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...

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...

btCollisionObject::isActive() will tell you if something's been put to sleep...

yup, it's the wrong way round. But it kind of makes sense as opposed to going "up" towards the "base"

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/) ...

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...

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...

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...

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...

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 ...

or even just
sorry, I was thinking in Ogre terms, which keeps the orientation & position separately

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...