[Bf-committers] Bullet physics update

Erwin Coumans erwin.coumans at gmail.com
Sat Mar 12 21:41:41 CET 2011


Hi,

I just committed the latest Bullet 2.78/trunk version in
Blender/extern/bullet2
and also added those few lines that enables the export of .bullet files
using BGE
python script command

PhysicsConstraints.exportBulletFile(char* fileName)

I haven't tested on all platforms yet, but I'll be checking the mailing list
and IRC this weekend and make sure things gets fixed asap.

Thanks!
Erwin

Juha Mäki-Kanto, yes this should be possible but I'm unfamiliar with bpy.
Someone more familiar should be able to do this.

On 2 March 2011 18:09, Juha Mäki-Kanto <kiskosika at gmail.com> wrote:

> I am sorry, I wasn't being clear; my intention was that there'd be a
> bpy-side python function that would start gameengine with the only intent
> of
> exporting a bullet-file (similarly to what I do with 2.49b). Would not
> require much coding since this would would effectively use the same
> c++-code
> as the bge-side function.
>
> I don't know if there are some hidden problems to this and I think both
> bge-
> and bpy-export functions are required since they serve different purposes.
> Bpy-version would just provide clean access for exporting the data.
>
> Newbie, be patient please :)
>
> 2011/3/3 Mitchell Stokes <mogurijin at gmail.com>
>
> > Joshua Leung's (Aligorith's) GSoC project last year involved Bullet
> > simulations in Blender (without using the BGE). I think he updated Bullet
> > in
> > his branch. You might want to have a chat with him.
> >
> > Cheers,
> > Mitchell Stokes
> >
> > On Wed, Mar 2, 2011 at 2:23 PM, Erwin Coumans <erwin.coumans at gmail.com
> > >wrote:
> >
> > > The BGE already has a perfect location for such 'exportBulletFile'
> method
> > > in
> > >  KX_PyConstraintBinding.cpp
> > > This would only be around 10 lines of code, and I will add this
> > > debugging/export option soon.
> > >
> > > Doing it outside of this KX_PyConstraintBinding.cpp might require much
> > more
> > > work.It requires an up and running Bullet physics world
> > > btDiscreteDynamicsWorld.
> > > Is someone volunteering to do this work?
> > > Thanks,
> > > Erwin
> > >
> > >
> > >
> > >
> > > On 2 March 2011 14:11, Juha Mäki-Kanto <kiskosika at gmail.com> wrote:
> > >
> > > > Hi,
> > > >
> > > > As Dalai Felinto said, I use the 2.49b export patch atm. to get the
> > > physics
> > > > data out of blender. I do this from makefiles so I've added a GE
> > > > commandline
> > > > param (-g) export_physics = filename; with it the gameengine
> > initializes,
> > > > does export and sets exitrequested to "true" before the main-loop.
> > > >
> > > > All in all it's not neat so a bpy-function with similar results would
> > be
> > > > nice from a model-exporters perspective, possibly with an
> > > > init_bge_pyscript-parameter which would allow advanced users to
> create
> > > > things only available from within the GE. I'm pretty new to bullet
> and
> > > > blender development so I'm not sure what problems this would cause
> > > compared
> > > > to just having a purely bge based solution.
> > > >
> > > > Thanks,
> > > > Juha
> > > >
> > > > 2011/3/2 Mitchell Stokes <mogurijin at gmail.com>
> > > >
> > > > > Nice to see you around again Erwin!
> > > > >
> > > > > bpy is available in the BGE if you're running from inside Blender.
> > > > However,
> > > > > not from the Blenderplayer. Since this is more of a debug thing, I
> > > think
> > > > > this would be acceptable.
> > > > >
> > > > > Cheers,
> > > > > Mitchell Stokes
> > > > >
> > > > > On Tue, Mar 1, 2011 at 11:38 AM, Erwin Coumans <
> > > erwin.coumans at gmail.com
> > > > > >wrote:
> > > > >
> > > > > > Hi,
> > > > > >
> > > > > > That is a good idea but I don't think it is a full replacement
> > unless
> > > > BPY
> > > > > > is
> > > > > > available within the BGE.
> > > > > >
> > > > > > Having the option to export within the BGE allows you to 'debug'
> > and
> > > > > export
> > > > > > a full running simulation.
> > > > > > Some constraints/joints are only added at run-time (vehicles for
> > > > > example).
> > > > > >
> > > > > > Is BPY that can access a running Bullet simulation, available
> > inside
> > > > BGE?
> > > > > > Thanks,
> > > > > > Erwin
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > > On 1 March 2011 11:23, Dalai Felinto <dfelinto at gmail.com> wrote:
> > > > > >
> > > > > > > Hi Erwin,
> > > > > > > > I plan to add a single BGE physics API to export to a .bulle
> > > file,
> > > > > for
> > > > > > > > example exportBullet(char* fileName);
> > > > > > >
> > > > > > > What if instead of a BGE API you do it as a bpy API?
> > > > > > > That way one can write an addon to export the .bulle files. It
> > > should
> > > > > > > already be possible now, but having an API for that can be
> easier
> > I
> > > > > > > guess.
> > > > > > >
> > > > > > > (as a matter of fact Juha Mäki-Kanto, who submitted the
> > > > RigidBodyJoint
> > > > > > > patch, uses Blender exactly for this, to export the .bulle for
> > his
> > > > > > > engine)
> > > > > > >
> > > > > > > --
> > > > > > > Dalai
> > > > >
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