[Bf-committers] [Bf-blender-cvs] SVN commit: /data/svn/bf-blender [15734] trunk/blender/source/blender/ blenkernel/intern/softbody.c: soft body bug fix own finding

[bjornmose]

Martin Poirier schrieb:
>
> --- On Thu, 7/24/08, Jens Ole Wund <bjornmose at gmx.net> wrote:
>
>   
>> Revision: 15734
>>          
>> http://projects.blender.org/plugins/scmsvn/viewcvs.php?view=rev&root=bf-blender&revision=15734
>> Author:   bjornmose
>> Date:     2008-07-24 14:27:31 +0200 (Thu, 24 Jul 2008)
>>
>> Log Message:
>> -----------
>>     
>
> <snip>
>
>   
>> -adapted effect of wind and fields on softbodies such that
>> softbody "particles" and particle
>> "particles" behave consistently
>> note! 
>> effect of wind is 1/25 compared to before   
>> other forces 1/10
>>     
>
> Hi,
>
> Wouldn't it be good to add some do versions code in that case so that old files work consistently (backward compat) after this change?
>
> Martin
>
>
>       
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>
>   
Would be nice to be backward compatible. But, that is not that easy.
Wind and other effectors settings work layer global on all objects, that 
is particles and soft bodies.
The problem is there is no convention on the units, so every system 
scales it ad hoc.The scale constants are hard coded and not stored in 
the .blend.
It is even worse, since some of the effectors yield direct forces 
instead of indicating a media moving, which is physically wrong and the 
softbody code cares for that.
/* See: a particle in moving media (alias wind) will synchronize it's 
motion to the meadia and not accelerate for ever as in a force field.
So seen strictly  effectors have to accumulate movement and forces 
separatly .. AFAIK only soft bodies are asking the effectos to do that
And yes, the code is that bad :(  All i did try to hide the mess to 
users **sigh**  */
Setting the scale values on object level while loading the file won't 
work for several reasons:
1. old files loaded will behave back compat until saved with the new 
version tag
2. for newly added effectors, should  the old scale be used or the new one?
3. how to keep track on mixed effector --> victim realations .. storing 
that matrix to the .blend is overkill IMHO and will lead to confusion 
why objects act different depending on their 'birth date'.

I'd be more than happy to resolve that but was running out of ideas to 
do it right .. any help ?
BM