Search found 51 matches

by d3x0r
Thu May 05, 2016 2:17 am
Forum: General Bullet Physics Support and Feedback
Topic: Question about 'gryscopic' forces
Replies: 1
Views: 1090

Question about 'gryscopic' forces

while porting this, and trying to grasp some of the math, especially to do with rotation results of collisions. There are things called 'gyroscopic' as variables, and they refer to the velocity of rotation and acceleration... is there any of the math in there for handling precession; or when applyin...
by d3x0r
Mon Feb 29, 2016 10:20 pm
Forum: General Bullet Physics Support and Feedback
Topic: Tilting Table - kinematic body force exerted on rotation
Replies: 8
Views: 3227

Re: Tilting Table - kinematic body force exerted on rotation

instead of modifying the table's position spacially and kepeing the same gravity vector, can't you just update what the ball thinks of as down? body.setGravity http://bulletphysics.org/Bullet/BulletFull/classbtRigidBody.html#a5aedec73517fb7b9cddcbd72663e0ddc then you don't have to worry about transl...
by d3x0r
Mon Feb 29, 2016 10:18 pm
Forum: General Bullet Physics Support and Feedback
Topic: Cant build bullet with USE_MSVC_RUNTIME_LIBRARY_DLL falg.
Replies: 8
Views: 3830

Re: Cant build bullet with USE_MSVC_RUNTIME_LIBRARY_DLL falg

(VS2015, not 2013) I also have been having problems getting examples to build.... GWEN CMakeLists.txt has --- ADD_DEFINITIONS( -DGLEW_STATIC -DGWEN_COMPILE_STATIC -D_HAS_EXCEPTIONS=0 -D_STATIC_CPPLIB) Remove _STATIC_CPPLIB and app examples build +++ ADD_DEFINITIONS( -DGLEW_STATIC -DGWEN_COMPILE_STAT...
by d3x0r
Wed Nov 18, 2015 8:12 am
Forum: General Bullet Physics Support and Feedback
Topic: btRigidBody is not rotating about any axis.
Replies: 1
Views: 3931

Re: btRigidBody is not rotating about any axis.

I have made box like bodies in ragdollDemo but the box never rotates about any axis. I can move the body from one place to another and it is colliding with other object very well. Any suggestion , on what I am doing wrong ? Did you solve this? It's from not doing something like { btScalar mass = 1;...
by d3x0r
Mon Nov 16, 2015 12:44 pm
Forum: General Bullet Physics Support and Feedback
Topic: Bullet on XNA
Replies: 61
Views: 122743

Re: Bullet on XNA

ya turned out I had a couple typos so in one direction with a static box and movable box worked the other way didn't... and sometimes the hash on the first was less than the hash on the second and vice versa... I ended up modifying the sort in both to sort on mass and then object type so I could hav...
by d3x0r
Mon Nov 16, 2015 3:17 am
Forum: General Bullet Physics Support and Feedback
Topic: Compound shape collision
Replies: 1
Views: 1595

Re: Compound shape collision

Oh I have to add the shapes before calling 'calculateLocalInertia'
by d3x0r
Mon Nov 16, 2015 12:37 am
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: vectormath library question
Replies: 2
Views: 5000

Re: vectormath library question

bullet doesn't use a 4x4 matrix. It uses a 4x3 (for alignment) matrix for orientation and a vector3 (which has 4 elements) for the origin.
(btTransform; composed of a btMatrix3x3 and a btVector3)
but there's no scaling...

So I dont think this will help you.
by d3x0r
Sun Nov 15, 2015 10:39 am
Forum: General Bullet Physics Support and Feedback
Topic: Compound shape collision
Replies: 1
Views: 1595

Compound shape collision

Another User Error.... nevermind
by d3x0r
Sat Nov 14, 2015 4:54 am
Forum: Release Announcements
Topic: Bullet 2.83 released on github: Example Browser, URDF
Replies: 8
Views: 54525

Re: Bullet 2.83 released on github

So what's on the plate for the future? I see some work in featherstone btMultiBody stuff... I also see some logic for tracking 'islands'.. which I guess are groups of related things that might collide. I would think that as an extension to that one might order collisions based on their collision wit...
by d3x0r
Sat Nov 14, 2015 4:46 am
Forum: General Bullet Physics Support and Feedback
Topic: Bullet on XNA
Replies: 61
Views: 122743

Re: Bullet on XNA

re: Interfaces to track structs; I was wrong. Unfortunately casting a struct to its interface makes a unique boxed instance of the value-type. really trying very hard to not leverage 'unsafe'. Oh and C++ (using vs2015) ends up allowing -0 which is reresentable with floats/double format as 0x80000000...
by d3x0r
Wed Nov 11, 2015 5:58 pm
Forum: General Bullet Physics Support and Feedback
Topic: Issues setting and using Hinge Constraint
Replies: 1
Views: 976

Re: Issues setting and using Hinge Constraint

*nevermind had codebases reversed*
by d3x0r
Tue Nov 10, 2015 12:47 am
Forum: General Bullet Physics Support and Feedback
Topic: Dynamic Voxel Body Considerations
Replies: 4
Views: 1467

Re: Dynamic Voxel Body Considerations

Hmm, the idea of decomposing into cubes is interesting, but not directly applicable since my voxels are meshed via Marching Cubes (and potentially via Dual Contouring in the future), which gives a relatively smooth mesh. Maybe there's another way to apply the general idea though, as an optimization...
by d3x0r
Mon Nov 09, 2015 7:58 pm
Forum: General Bullet Physics Support and Feedback
Topic: Dynamic Voxel Body Considerations
Replies: 4
Views: 1467

Re: Dynamic Voxel Body Considerations

Actually was just thinking - that scale will lose precision... it's really only good for 6.7 million range. which is like 1/8 the earth circumferance in meters and only 2/3 the moon's circumferance... but still pretty darn large.
by d3x0r
Mon Nov 09, 2015 6:15 pm
Forum: General Bullet Physics Support and Feedback
Topic: Dynamic Voxel Body Considerations
Replies: 4
Views: 1467

Re: Dynamic Voxel Body Considerations

I would think a compound body of multiple cube shapes would be more efficient. Since voxels are all the same size; just one instance of the shape needs to be created and the box collider looks more efficient than triangle mesh. Each shape added to a compound shape has a transform within the compound...
by d3x0r
Mon Nov 09, 2015 9:17 am
Forum: General Bullet Physics Support and Feedback
Topic: setUserIndex alternative?
Replies: 6
Views: 1883

Re: setUserIndex alternative?

I mean that it work exactly the same in that if you don't setUserIndex to anything getUserIndex will be 0... same if you don't setUserPointer, getUserPointer will of course be null. I'm sorry but I'm not very pro on C++. Can you go a little more in depth on how to do it with examples? Perhaps with ...