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Soft Body Aero on/off switch
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Create a soft body
turn on aero and give aero a factor
turn off aero
It is like aero is still switched on.

In the attached file you see:
a) soft body without aero
b) copy of a) with aero
c) copy of b) aero swichted off

b) = c)

Win 7 / 8 GB RAM
Intel Q6600 2,40Ghz
ATI Radeon X1950 / Driver 8.593.100.0



Event Timeline

Assigning to Jens. Is this something in the sim? Or point cache related?

This is a glitch in the UI:
The checker labeled 'aero' switches between two aerodynamic models.
Unchecked : 'simple' drag Checked : 'sailing straw' dynamics
To turn off aerodynamics the factor has to be set to zero.
both b) and c) have the same factor thus the effect working.
The symmetric shape of the objects however make the 'sailing straw' effect to be balance out --> thus no to very little difference in this case.
Even using aero in this case at all seems doubtable because it will give similar results with much 'cheaper' friction.

I was about to remove it from the soft body module, since i felt it was too 'clothy'
and should be ported there.
But left it in for 3 reasons:
1. back compatibility
2. Some users prefer using soft bodies for cloth.
3. It could be used to simulate wind forces on structures as buildings, trees ..
along with mesh modifiers jelly fish in waves..
and all the other use cases i fail to think of.
Attached a rather cloth like example.

Finally i refuse to see a bug in soft body module or point cache,
but see a bad user interface.
Since UI never was and never will be a region i feel comfortable in,
I'd rather have the fix done by someone who knows what he/her is doing.

Would be correct .. but looks ugly
class PHYSICS_PT_softbody_edge(PhysicButtonsPanel):
# col.prop(softbody, "new_aero", text="Aero")
# sub = col.column()
# sub.enabled = softbody.new_aero
# sub.prop(softbody, "aero", text="Factor")
col.label(text="Extra Aerodynamics:")
col.prop(softbody, "aero", text="Factor")
sub = col.column()
sub.enabled = > 0
sub.prop(softbody, "new_aero", text="Straw Dynamics")

For smart users:
do you know you could even patch that to your running system by editing the proper python script ?

Jens, so if i understand correctly rather than a toggle, it should really be represented by a 'radio' selector or menu, choosing between two options, right? What would those two options be called? I'm not sure what you mean by "sailing straw". If you can tell me this I can fix it.


Hi Matt,
just committed 'my' version of it.
But, yes any 'option chooser' would make it more user friendly.
mind snip -> 'she was searching for simple words even adults could understand'
stolen from,_This_Is_Anna
so lets give it a try
starting off with 2 vertexes (vertices I'd prefer but spell checker complains)
They may feel drag to surrounding media movement.
But if there was an edge there was a force all along the edge to feel that drag.
Well this is option 1 .. ( item not checked )
depending on the direction the edge moves ( related to the gas or what ever ) there is a
additional force .. see 'lift'
and 'sailing straw' ( item checked ) gives a 1rst order estimation for that ..
hum did answer it on the way .. why not label it '1rst order lift' pretty sure any adult will understand!?
So i am pretty lost how to label it .. it does simulate an aerodynamic effect, which occurs when an object has more than 1 dimension .. ( evil math thinking )
but does not take faces (which would not be too hard to do, but since there was no yelling for that it did not )
All it is about is refining aerodynamic effects which IMHO would not belong to a basic soft body module .. well I was tempted to drive it to the limits .. and some users may have a way to use it .. I would not want to take it away unless we can point to an equivalent replacement.

Hi Jens, I saw the commit. I can turn that into an option menu - based on your description and wiki page I think a good name would be to have two options like this?:

[ Simple | Lift Force ]

I'll commit this, and if it's terribly wrong, please let me know :)


Matt Ebb (broken) closed this task as Resolved.Jun 30 2010, 4:34 AM