[opensource-dev] Soft body physics

Dale Mahalko dmahalko at gmail.com
Thu Apr 8 16:04:35 PDT 2010

Can you point to anything in 3D animation that already does this sort
of thing? I don't think it exists.

The idea sounds reminiscent of an idea I posted on this list a few
years ago, wrapping a sculptie mesh around a collection of prims and
"deflating" the mesh until its vertices form-fit the prims within,
sort of like vacuum-forming with plastic, to quickly make a multiprim
object into a single sculptie.


Sending raw soft-mesh vertex points to the client to accurately show
the soft mesh shape would likely be far too slow. A simple mesh can
contain a few hundred points, each with X/Y/Z coordinates, and these
must all be adjusted for each new "frame" of the 3D renderer.

You would probably have to simplify and generalize the soft body
modeling to make it fast enough for a slow network connection, and
leave the actual modeling up to the local computer. Define general
static forces that pin the mesh around its edge and on its surface,
such as the flattening buttons like on chair cushions. To "inflate"
the mesh into a bun or balloon, assign a general direction of billow.
And if desired, also adjust the elasticity of the rays linking
vertices together to tighten up or loosen the overall shape, such as
along seams on pillows..

To deform the mesh the server only sends a force and a 3D impression
shape to the client, such as a sphere X meters in diameter pressing
into the mesh surface with Y newtons of force. The client then uses
that simple data in combination with the defined static forces to
dynamically deform the soft mesh vertices, such as representing your
avatar's feet pushing down on surface of a trampoline.

Just don't ask me to program that. :-)

- Dale Mahalko / Scalar Tardis

On Wed, Apr 7, 2010 at 7:25 PM, Glen Canaday <gcanaday at gmail.com> wrote:
> I can imagine fields of waving grass, rubber couches and trampolines

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