Search found 237 matches

by dphil
Sun Dec 02, 2012 10:18 pm
Forum: General Bullet Physics Support and Feedback
Topic: About the opacity of softbody and rigidbody in Bullet
Replies: 1
Views: 1221

Re: About the opacity of softbody and rigidbody in Bullet

[Note: Topic moved from Career Opportunities] This sounds like a graphics issue, not a physics one, so I would consult graphics forums. Offhand, my first guess would be to ensure appropriate drawing order of your renderables (see http://www.opengl.org/archives/resources/faq/technical/transparency.ht...
by dphil
Sun Dec 02, 2012 9:13 pm
Forum: General Bullet Physics Support and Feedback
Topic: Single vertex collision shape?
Replies: 1
Views: 1266

Single vertex collision shape?

I have a ghost cube that should detect which of various moving rigid spheres are inside it (the spheres float around and may or may not be colliding with the cube at any given time). For me, a necessary and sufficient condition of being considered "inside" is that the centre of the sphere is inside ...
by dphil
Sun Mar 11, 2012 8:45 pm
Forum: General Bullet Physics Support and Feedback
Topic: Need help with bullet contact triggers
Replies: 8
Views: 4007

Re: Need help with bullet contact triggers

1- So what is the best way to find collisions and trigger a message to somewhere else, 2- how would I make some rigid bodies not collide with eachother but trigger a contact message 3- and how would I have that triggered message informing that CollidableObject A collided with CollidableObject B ins...
by dphil
Sun Mar 11, 2012 8:27 pm
Forum: General Bullet Physics Support and Feedback
Topic: Convex Hull: order of points?
Replies: 3
Views: 1705

Re: Convex Hull: order of points?

No I don't believe so.
by dphil
Thu Mar 08, 2012 2:32 am
Forum: General Bullet Physics Support and Feedback
Topic: Soft body development
Replies: 1
Views: 994

Re: Soft body development

I believe soft body dynamics have received quite a bit of attention, particularly in regard to GPU acceleration. But these changes are mostly in the 3.x branch, I believe, so are not available in any stable distribution yet.
by dphil
Thu Feb 23, 2012 7:26 am
Forum: General Bullet Physics Support and Feedback
Topic: Bullet crash with debug viewer in debugDrawWorld()
Replies: 4
Views: 2203

Re: Bullet crash with debug viewer in debugDrawWorld()

Everything looks ok to me. Can you check your Bullet source and see what line 1444 is (if there is one)?
by dphil
Thu Feb 16, 2012 9:03 pm
Forum: General Bullet Physics Support and Feedback
Topic: what is the purpose of those methods ?
Replies: 3
Views: 1805

Re: what is the purpose of those methods ?

Yes, the 2 collision object parameters in addSingleResult are 2 objects that are detected to be colliding. The "index" parameter for each object is the index of the specific triangle in contact, if the object's shape is a triangle mesh (ex. btTriangleMeshShape). The partId refers to the part of the ...
by dphil
Thu Feb 16, 2012 4:44 pm
Forum: General Bullet Physics Support and Feedback
Topic: When should I apply forces to my rigid bodies?
Replies: 3
Views: 1572

Re: When should I apply forces to my rigid bodies?

Alternatively, if you know your object will always be in motion (or if any performance you might gain from sleeping is unimportant to you), then if you want you could just turn off the sleep behaviour altogether when the body is created: rigidBody->setActivationState(DISABLE_DEACTIVATION); in which ...
by dphil
Thu Feb 16, 2012 3:40 pm
Forum: General Bullet Physics Support and Feedback
Topic: When should I apply forces to my rigid bodies?
Replies: 3
Views: 1572

Re: When should I apply forces to my rigid bodies?

During your main application loop should be fine, before or after calling Bullet's stepSimulation(). Objects can go to sleep if they are inactive for a period of time, meaning they need to be woken up to respond to manual forces. Call rigidBody->activate(true); after your force application if you ar...
by dphil
Tue Feb 14, 2012 7:25 pm
Forum: General Bullet Physics Support and Feedback
Topic: btIDebugDraw problems
Replies: 12
Views: 7540

Re: btIDebugDraw problems

I made a new test project (Cocoa Application), to which I added the Bullet frameworks, OpenGL.framework, and GLUT.framework. I copied your myDebug implementation above (and I made up an appropriate header for it) and it built and ran fine. So I'm not sure what the problem is... You could try the sam...
by dphil
Tue Feb 14, 2012 3:35 am
Forum: General Bullet Physics Support and Feedback
Topic: Debug drawer only draws diamonds when I want spheres?
Replies: 2
Views: 1972

Re: Debug drawer only draws diamonds when I want spheres?

btIDebugDraw declares two drawSphere functions, and my experience in the past (and by looking at Bullet's source code) is that this one: virtual void drawSphere (const btVector3 &p, btScalar radius, const btVector3 &color); is never called. The one you should implement/override is virtual void drawS...
by dphil
Mon Feb 13, 2012 10:51 pm
Forum: General Bullet Physics Support and Feedback
Topic: btIDebugDraw problems
Replies: 12
Views: 7540

Re: btIDebugDraw problems

For the drawing functions, implementing a rendering call in drawLine is sufficient to get something going, but yes for the sake of completing the abstract superclass you need those other function definitions in there, even if they are blank. Ok, looking at your code I see another little detail that ...
by dphil
Sun Feb 12, 2012 1:28 am
Forum: General Bullet Physics Support and Feedback
Topic: btIDebugDraw problems
Replies: 12
Views: 7540

Re: btIDebugDraw problems

Thanks for you help. I don't have a debug drawer implementation - that must be my problem. How would I do that? Well, once you set the debug drawer for the world, Bullet will make calls to the functions listed in the btIDebugDraw interface. You just need to implement those functions so they actuall...
by dphil
Sat Feb 11, 2012 11:29 pm
Forum: General Bullet Physics Support and Feedback
Topic: btIDebugDraw problems
Replies: 12
Views: 7540

Re: btIDebugDraw problems

Do you actually have an debug drawer implementation? I see you are declaring the debugDrawer variable, but not assigning anything to it (maybe you simply left the assignment part out, but it might be helpful to see). Keep in mind that btIDebugDraw is really just an interface that you need to subclas...
by dphil
Thu Feb 09, 2012 11:20 pm
Forum: General Bullet Physics Support and Feedback
Topic: Simulate gun bullets with high speed collision misses
Replies: 1
Views: 1534

Re: Simulate gun bullets with high speed collision misses

Continuous collision detection is what you really want for this sort of thing, but I'm not sure what state Bullet's CCD side is in. I've never used it myself. Otherwise, you could approximate it with per-step raycasts as you mention. I'm not sure if the trajectory (straight line, arc, etc) of the bu...