[LSynth] Suggestions

[Stan Isachenko]

I think we need Lsynth option, or other tool to create cloth elements, such as sails or other. I really don't understand how to realise it( But I think it is possible.

[Don Heyse]

Something like this draping demo as a frontend to pathtruder would probably do it.

[Don Heyse]

Also, this is probably as good a place as any to mention the sometimes hard to find net generator spreadsheet.

[Philippe Hurbain]

Don Heyse Wrote:
-------------------------------------------------------
> Something like
> [url=http://www.custom-logic.com/exp/cloth/cloth.h
> tml]this draping demo[/url] as a frontend to
> [url=http://www.philohome.com/isecalc/pathtruder.h
> tm]pathtruder[/url] would probably do it.
I am afraid pathtruder would be of little use here. If you have the vertices coordinates of a triangulated mesh then you have the mesh itself...

[Don Heyse]

Hmmm, I guess you're right about pathtruder. Oh well.

By the way, here's another example cloth simulation demo to get you all thinking. All we need is a button that says stop moving now and gimme the mesh in ldraw format...

Oooh, this one comes with source code. Who wants to add that button?

[Philippe Hurbain]

I am not sure that these simulations provides enough flexibility for LDraw usage: how do we give the right shape (not rectangular)? how do we specify pinning points not in the same plane? There seems to be no notion of rigidity/elasticity of the cloth (eg. minifig capes are quite rigid).

[Tim Gould]

If you associate a normal with each point you can add a rotational spring constant by looking at the dot products of neighbouring normals. It's not going to do cape too well since they're papery (which is different physics again) but it would give more accurate stiffness.[1]

The hard part is not so much doing the physics of the cloth, but dealing with the constraints. Making sure the cloth doesn't pass through itself is challenging enough, making sure it doesn't pass through anything else is even harder.

I think I could deal with the physics for the cape part but I simply don't have any time for the programming. If anyone is desperate to do some coding I'd be happy enough to help.

Tim

[1] Actually I've got an idea how you could do paper too by considering lines as potential creases but it all gets a bit nasty.