[Bf-committers] New force type patch: Spring (Farsthary)

Raul Fernandez Hernandez raulf at info.upr.edu.cu
Wed Dec 16 17:05:33 CET 2009

Hi :)

> Hi Raul ,
> hum .. still missing the point
> to me it looks like a force field  ( potential )  .. having a minimum
> at  R ( which you define as rest length )

  Yes, that's the potential energy of the hook's force, there's nothing
troublesome there :)

> So..
> 1. what is the point in having a potential  arranging  a mesh close to a
> S3 (sphere in 3D )

 That was just a quick/useless set up to show the effect, that is not a
real use case, a more real use case is the first video in my site, the
simple.wmv  where each particle extend springs to the rest, when you have
tons of points pulling/pushing themselves around their relatives rest
lengths interesting things happen and shapes arise, that bunch of points
(particles, etc) became elastic :)
  Also, in the first useless example you could set the center not just the
force object center but the objects vertices or every surface point and
then you will get more complex behaviors, not only OSCILATING the mesh
around an S3.

> 2. the lack of other forces .. like friction to surrounding media ..
> even internal friction ..  makes it look quite. say .incomplete
> but still
> may be i am missing the very spot, enlighten me
> BM

 This force perfectly interacts with the rest of the forces, and although
adding velocity damping is not difficult at all I think is redundant
since those effects could be achieved with the particle damping factor in
the Newtonian panel. Think of it as a system and not as an isolated
force, the rest of the system have drag forces,damp factors etc, so for
complex behaviors like dampen springs you just set them also and there's
no need to increase force complexity adding those alreday calculated
therms to the force source code.
 (Againg, if there's some use cases that justify it in the force source
code it will be a matter of minutes to add it)

                               Cheers   Farsthary

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