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Member Since 19 Sep 2012
Offline Last Active Yesterday, 06:41 AM

#5286642 Creating Box RigidBody From AABB

Posted by xexuxjy on 13 April 2016 - 07:00 AM

Sure. Was trying to remember if bullet allowed you to change the centre of mass  easily and it doesn't though there are ways to work around it using compound shapes but wouldn't recommend it. One solution Erwin mentions below in :




is to let your motion state do the graphics offset for you. I'd still probably recommend trying to keep the pivot centred though.

#5286618 Creating Box RigidBody From AABB

Posted by xexuxjy on 13 April 2016 - 03:08 AM

Bullet box shape expects a center of mass (center of object) at local zero point to box, so you can imagine that instead of your box going from from 0,0,0->1,1,1 it goes from -0.5,-0.5,-0.5 -> 0.5,0.5,0.5 . I think you'll find using your box much easier in general if you think of it centered that way.


You do not need to recalculate the AABB each frame (bullet will do it for you based on the rotation of the object). if you're using the btMotionState to link your model and the rigidbody you should be able to just update your models transform based on that.

#5254659 Anyone using Bullet serialization?

Posted by xexuxjy on 29 September 2015 - 02:10 PM

You've probably seen this :




But in general the serialization stuff isn't really that useful apart from helping to debug bullet issues....  You can serialize individual objects, but it's one of these things that snow balls, so a rigid body needs a collision shape, which may then need to serialize the accelerator like the trees for BvhTriangleMesh and so on.


I think the 32k issue you've got above may not be a problem though. The serializer works in chunks so that's probably just the default chunk size, you could add a lot more and have it fit inside that same chunk.

#5219306 game lib for c++

Posted by xexuxjy on 26 March 2015 - 07:49 AM

I thought unity used c# as one of it's options, rather then c# based? same for JavaScript?

#5157779 Bullet Physics - Objects pass through certain triangles in mesh

Posted by xexuxjy on 03 June 2014 - 05:04 AM

Bullet debug draw should give you the ability to draw contact normals and so on which should help.

Does this problem occur with all collision shapes for just spheres ? 2.82 seems to have have a few new issues with heightfield and triangle mesh collisions which previous versions didn't so that might also be worth looking at.

What is the size of your sphere (minGroupRange ) ?

#5131004 Why is my JFrame or my JPanel not appearing?

Posted by xexuxjy on 13 February 2014 - 04:13 AM

Also worth noting that some of your if statements have semi-colons directly after them so probably aren't doing what you want....

#5119709 XNA C# Game - Transition problems

Posted by xexuxjy on 28 December 2013 - 02:46 PM

Don't think what you're doing is broken at all , and there are  lots of ways to achieve the effect., I think the NPE I got was just maybe an error you hadn't reached yet as the transition hadn't fully occurred. For one of my projects I used a gamestate manager based on one of the MS samples : http://xbox.create.msdn.com/en-US/education/catalog/sample/game_state_management  , (my modified version part of a project at : https://code.google.com/p/xexuxjy-xna-games/source/browse/#svn%2Ftrunk%2FGladius%2FGladius%2Fgamestatemanagement)

#5119530 XNA C# Game - Transition problems

Posted by xexuxjy on 27 December 2013 - 11:53 AM

Yup, I saw all that, Just trying again and the key for activating the FadeAffect in LoadContent is Effects/FadeEffect, but the key in the Image is just FadeEffect so that doesn't trigger. updating SplashScreen.xml fixes that. I'm still a bit puzzled by the start and end alpha values for Transition - it seems that after 1 update you have alpha at 0.0 or 1.0 which stops the transition. If you change the start value to say, 0.01 and change the effect key then you'll get the screen fade, though it then NPE's on a load content when it finishes :)

#5103444 FBX model animation glitches with XNA importer

Posted by xexuxjy on 22 October 2013 - 12:05 PM

which models is it, the 3drt ones?  I had a few issues at first (mainly animation speed, but I think also some odd behaviour like you're seeing).

this is my current code if it helps :


#5101775 Physics engine or DIY?

Posted by xexuxjy on 16 October 2013 - 05:26 AM

Did you use the vs2005.bat build file to generate your project? haven't tried that one for a while, but it should be valid.

#5075417 low-budget ways of testing performance ?

Posted by xexuxjy on 05 July 2013 - 03:45 AM

Does anyone have any recommendations for ways of testing the performance of a game (in this case using XNA) on different machine specs? (cpu,memory,graphics card) . My development machine is reasonably high spec and I'm concerned that it's hiding various problems that would become more apparent on other machines (I have some evidence this is happening with a tester but we're trying to figure out roughly where the problem lies). I know that the ideal solution would just be to have a range of different machines at different specs, but as this is just a friend and I working on stuff for fun thats a bit over the top. Is it possible to setup vm's with limited resources to test this, or does anyone have a recommendation?



#5039989 Licensing Code Releases using Bullet 3D

Posted by xexuxjy on 06 March 2013 - 08:58 AM

Not really true - lots of stuff in bullet is non virtual on purpose for performance reasons, I've found it's definitely much easier just to add stuff in directly and a lot of people seem to have custom bullet builds.

#5003232 Detect collision only with a shape (No physics)

Posted by xexuxjy on 22 November 2012 - 07:36 AM

as both btGhostObject and btRigidBody derive from btCollisionObject you can just do :

btSphereShape *sphere = new btSphereShape(500.0f);
btGhostObject* ghost = new btGhostObject();

(which you could also do on the rigid body rather than setting the collision shape in the btRigidBodyConstructionInfo and passing that to the btRigidBody ctor.

make sure you do all this before adding it to the collisionWorld though.

#4981706 Is XNA dying and MS forcing to C++?

Posted by xexuxjy on 19 September 2012 - 09:05 AM

Microsoft do seem to be trying to kill it off, they've recently split the creators section of their site into phone/indie games sections and in the process broken nearly every single google link to the data there. The general impression is that they're just trying to make it fade away without making any real announcments on it. All their current efforst seem to be on Windows Phone and Tablet work, and while XNA is valid on the phone for now I really get the impression they'll start pushing more forcibly to c++.
Having saiid all that XNA is still a pretty good framework and the with some of the replacements mentioned below you'll be able to get a lot of stuff done with it very easily.