[resolved] serialization differences depending on Blender

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cyrfer
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Joined: Mon Sep 12, 2011 6:42 pm

[resolved] serialization differences depending on Blender

Post by cyrfer »

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!
Last edited by cyrfer on Fri Aug 24, 2012 9:05 pm, edited 1 time in total.
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Erwin Coumans
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Re: serialization differences depending on Blender build

Post by Erwin Coumans »

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
cyrfer
Posts: 9
Joined: Mon Sep 12, 2011 6:42 pm

Re: serialization differences depending on Blender build

Post by cyrfer »

Thanks for looking into this issue, reported as Issue 618.
John
cyrfer
Posts: 9
Joined: Mon Sep 12, 2011 6:42 pm

Re: serialization differences depending on Blender build

Post by cyrfer »

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!
Last edited by cyrfer on Wed Aug 01, 2012 8:57 pm, edited 1 time in total.
cyrfer
Posts: 9
Joined: Mon Sep 12, 2011 6:42 pm

Re: serialization differences depending on Blender build

Post by cyrfer »

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...
cyrfer
Posts: 9
Joined: Mon Sep 12, 2011 6:42 pm

Re: serialization differences depending on Blender build

Post by cyrfer »

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