Real-Time Physics Simulation Forum

I've pinned down the problem to the function: void btCompoundShape::calculateLocalInertia(btScalar mass,btVector3& inertia) const When this is called during the btRigidBody creation process, calculates the inertia based on the size of the AABB. The AABB obviously changes when a second shape is a...

I'm still struggling with this problem, and thought I'd try to explain exactly what seems to happen. I am building a game tool which allows you to connect objects together to form bigger compound models. My CModel class has a btCompoundShape. When creating the CModel, the first child shape I add to ...

Hello, I am slightly confused about the CORRECT way to deduce the position of children of btCompoundShapes. I have a concave object, actually composed of several btBoxShape collision objects. These children are added like this: btTransform t; t.setIdentity(); t.setOrigin( offset ); m_compoundShape->...

Hi, I've been using Bullet happily for a while, with rigid bodies crashing about in a dynamic world. My new problem comes with the introduction of btCompound shapes. How do I apply forces to a compound shape? I tried iterating thru the children and applying the forces to each, but that as expected, ...

Hello, I am interested in btCompoundShape so I started by looking at the forklift demo. It appears the collision shapes are combined into a btCompoundShape, then the rigid object is created with the compound shape. Am I right in thinking that there is no way to ADD a collision shape to an existing r...

Hi Erwin,

Thanks, this is what I have done.

It is not perfect for my app, but not bad. I just hoped there might be a 'live' mutator....

Any hey it works!

One question, how does the XYZ coords of bullet relate to the XYZ of directX? I have noticed a few bounding box anomalies.

Thanks
Si

Thanks Sparkprime, o bullet master.

That is perfect!

I still think apply forces to the wings would suffer the same problem. A wing applies a force relative to its local orientation, not the world space. Perhaps one approach is to get the orientation quaternion of an object and transform the force by this. This converts the force in local space to its ...

Hi, At present, my rigidBodies are getting info on the collision shape to use in their constructor, using rigidBodyConstructionInfo. Is there any way to update the size of the collision shape after construction? I don't really want to have to delete and recreate the whole object. Basically I am look...

Thanks for the reply

AxeD wrote:

Code: Select all

	body->setWorldTransform(trans);

This is overriding the position and rotation of the object. I am wanting to apply forces to the object instead, just as ailerons or a rudder might do....

sparkprime wrote: Alternatively you can activate() it whenever you apply a force/torque.

Thanks, this cured it. It still stops but responds to new commands now.

I'll play with the sleep thresholds too.

Seeing as rigidBody::applyTorque() acts in world space, how can I rotate an object around its local axes?

Effectively, I am looking for a way to produce Pitch Roll and Yaw movement.

Thanks

Simon

Beware, Bullet newbie alert! I've placed a btRigidBody in a btDiscreteDynamics world as per basic demo. I am using btRigidBody->applyTorque() to perform simple rotation of the rigid body in two axes, X and Y (Y is vertical). This works fine, then occasionally the object will suddenly stop rotating a...

Hi! My game only had a simple hand built movement system up until now, with very crude AABB collision detection. I am currently upgrading to Bullet, and like what I see so far. My question is how to use Bullet in a large play area, and how to divide the processing between client and server. Firstly,...