Search found 229 matches

by pico
Sat Jul 18, 2009 8:28 am
Forum: General Bullet Physics Support and Feedback
Topic: Jumpy kinematic->dynamic collisions at small timesteps
Replies: 17
Views: 19100

Re: Jumpy kinematic->dynamic collisions at small timesteps

Hi,

i assume you dont use a motionState for the kinematic bodies. This should interpolate automatically between the simulation frames.
by pico
Sat Jul 18, 2009 8:22 am
Forum: General Bullet Physics Support and Feedback
Topic: Correct way to move objects around in game
Replies: 7
Views: 10170

Re: Correct way to move objects around in game

Hi, actors are called btRigidBodies in Bullet. Both constructs have almost the same set of functionality. So applying a force is what you also would do in Physx. Maybe you refer to CharacterControllers or KinematicBodies? Those can be controlled more directly. For character controllers check out the...
by pico
Mon Jun 22, 2009 9:34 am
Forum: General Bullet Physics Support and Feedback
Topic: How to detect which CollisionObject was hit ?
Replies: 4
Views: 3643

Re: How to detect which CollisionObject was hit ?

Hi,

you can access the ray result m_collisionObject.

I'm not sure why you want to know the shape. Usually people use the m_userData in m_collisionObject for a pointer to their internal game object structure.
If you just need to seperate objects you can use different filtergroups.
by pico
Mon Jun 22, 2009 6:26 am
Forum: General Bullet Physics Support and Feedback
Topic: How to detect which CollisionObject was hit ?
Replies: 4
Views: 3643

Re: How to detect which CollisionObject was hit ?

Hi,

you can use the public property m_userObjectPointer in the collisionObject to store user data.
by pico
Sat Jun 20, 2009 7:35 am
Forum: General Bullet Physics Support and Feedback
Topic: Objects do not react to forces after settling
Replies: 2
Views: 2467

Re: Objects do not react to forces after settling

Hi,

the object felt asleep to save CPU. You can disable object sleeping. Or you can activate objects when you give them impulses.

see:
void btCollisionObject::activate(bool forceActivation)
void btCollisionObject::setActivationState(int newState)
by pico
Fri Jun 19, 2009 3:59 pm
Forum: General Bullet Physics Support and Feedback
Topic: Howto detect collision Single Ray with single CollisionShape
Replies: 6
Views: 5113

Re: Howto detect collision Single Ray with single CollisionShape

"The information we get from the raycast includes what shape we hit, how far away the shape is from the origin of the ray, the point of impact of the ray, the normal to the impact on the shape, and, if the shape hit is a triangle mesh, the surface triangle hit and the barycentric coordinates o...
by pico
Fri Jun 19, 2009 3:46 pm
Forum: General Bullet Physics Support and Feedback
Topic: Letting two btKinematicCharacterControllers collide
Replies: 2
Views: 2938

Re: Letting two btKinematicCharacterControllers collide

Hi, i would suggest to modify/make another recoverFromPenetration() routine in the character contoller. When you go through the manifolds check if both bodies are characters. If yes, do something like this: m_currentPosition += pt.m_normalWorldOnB * directionSign * pt.getDistance() * btScalar(0.2); ...
by pico
Fri Jun 19, 2009 3:27 pm
Forum: General Bullet Physics Support and Feedback
Topic: Want a collision detection notification without the physics
Replies: 11
Views: 12675

Re: Want a collision detection notification without the physics

Hi,

i'm not sure if this works at all (scaling at runtime). If yes, then the problem could be that the kinematic object is set to inactive state. If this is the case then its AABB is no more updated. You can call updateAABB or set it active. Maybe this helps.
by pico
Fri Jun 19, 2009 8:10 am
Forum: General Bullet Physics Support and Feedback
Topic: Loosing gravity
Replies: 2
Views: 2553

Re: Loosing gravity

Hi,

when i understand right then you have two boxes, one ontop the other. Then you remove the bottom box and the top box doens't move, right? The reason is the box is 'sleeping'. It doesnt recognize the bottom is removed. To fix that you can disable object sleeping.
by pico
Fri Jun 19, 2009 8:09 am
Forum: General Bullet Physics Support and Feedback
Topic: Inactive objects still collides
Replies: 5
Views: 6771

Re: Inactive objects still collides

Hi, people may want to get collisions for non active bodies and static bodies. An example would be to query if there are bodies within a 'trigger' volume. The trigger volume is static and the bodies are sleeping. With your modification there would be no more bodies reported after they fall asleep. A...
by pico
Fri Jun 19, 2009 7:59 am
Forum: General Bullet Physics Support and Feedback
Topic: questions on ghosts
Replies: 2
Views: 2698

Re: questions on ghosts

Hi,

the sweep tests test a collisionShape with the objects within the ghostObject. So you save asking the broadphase for collisions. This is pretty nice for character controllers.
by pico
Thu Jun 18, 2009 9:12 am
Forum: General Bullet Physics Support and Feedback
Topic: Degrading performance (binary demo and VIDEO included)
Replies: 7
Views: 7425

Re: Degrading performance (binary demo included)

Hi, i recommend to display to btProfilers. So you can easily spot where the performance goes. Form your other post i saw you use a 1/200s timestep. Do you need such a high timestep? Did you already try 1/60s. This would give you instantely 3 times more performance. Do you use a cylinder primitive or...
by pico
Thu Jun 18, 2009 9:04 am
Forum: General Bullet Physics Support and Feedback
Topic: Want a collision detection notification without the physics
Replies: 11
Views: 12675

Re: Want a collision detection notification without the physics

Hi, you don't need actually a ghost object for that. Just setting NO RESPONSE is enough. You can get the contact manifolds but no interaction will occur. Be also sure to make that object kinematic so that physics doesn't affects it. Ghost objects are only needed if you want to keep track about all c...
by pico
Wed Jun 17, 2009 12:02 pm
Forum: General Bullet Physics Support and Feedback
Topic: Sphere cast vs ray cast
Replies: 3
Views: 5883

Re: Sphere cast vs ray cast

Hi,

i assume the float precision is simply to low to get proper collision with near zero scale.
by pico
Tue Jun 16, 2009 8:25 am
Forum: General Bullet Physics Support and Feedback
Topic: Possible heap corruption with 2.75?
Replies: 4
Views: 4631

Re: Possible heap corruption with 2.75?

Good that i could help you. Explanation: With 2.75 there is now an array for non static bodies to make updates faster. The pointers in this array need to be freed as well when you remove a body. *RemoveCollisionObject only removes the collision object. *RemoveRigidBodies does remove the array pointe...