Physics Simulation Forum

Hi,
I'm using the technique to export a Bullet file (the scene has static objects, dynamic rigid body objects, and ragdolls) from within the Blender Game Engine via a keyboard controller hooked up to my export script. This process seems to work pretty well, with one issue.

I am seeing slightly different results when using Blender-64 or Blender-32. I suspect the issue is in the Bullet serialization. When my 32 bit application loads the Bullet file exported from Blender 32 bit on a 32 bit PC, I see no problems. If I use the same Bullet file (still from 32 bit Blender) on a 64 bit PC with my 32 bit application, I see bad floating point values (e.g. -1.#IND) for at least one of the ragdoll objects (btCollisionObject has a bad m_basis in its m_worldTransform).

All these tests are in Windows.

I am in the process of testing an export with 64 bit Blender for my 64 bit PC (with 32 bit application). I will post back with these results later today.
Where might this difference be coming from? Is it Bullet serialization or deserialization or both? Has anyone else experienced this?

I found that I need to use a 32-bit build of Blender to export a file. I performed this on my 64-bit PC, but I'm not sure if the platform is important.

Thanks for any tips!

This should not happen, Bullet serialization was designed to solve 32bit/64bit, endianness and versioning issues.

Can you file an issue in the Bullet tracker (http://code.google.com/p/bullet/issues/list) with
1) Blender full version info
2) attach the .blend file
3) attach the .bullet file that causes problems?
Thanks a lot,
Erwin

Thanks for looking into this issue, reported as Issue 618.
John

Thank you for the fix! The diff looks like a great improvement. I hope to test it soon with Sergej's help.
http://code.google.com/p/bullet/issues/ ... id=618#c15

Here is the bug report for Blender.
http://projects.blender.org/tracker/?fu ... group_id=9

One thing that may hold back Blender from using this fix is that Bullet does not have a new release. Will there be a new release soon? I know they are trying to release around SIGGRAPH time, but that may be sliding...

PS. Will you be attending? I'll be there!

Actually, if I now understand the diff from the patch, the fixes were only in READING the .bullet file. Hopefully, I can test this fix in my code without a new Blender build. Will get back to you on this...

I am told the changes to Bullet in r2542 have helped our issues when reading .bullet files. Thanks again!