Cloth?

Compiling, libraries, modules, coding guidelines and porting

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ilac
Posts: 131
Joined: Mon Oct 14, 2002 8:24 am

Post by ilac » Thu Aug 14, 2003 10:35 am

LukeW wrote:
theeth wrote:parameters like stiffness would be ultra nice if they could be adjusted in a per vertex maner using a vertex painting way.

Martin
I think that should be optional though since most fabrics would be fairly uniformly stiff and it would run (a bit?) faster if it is uniform.
I think its more an issue of added control in what is ultimately a virtual world! Being able to vary stiffness might be handy to represent parts of cloth under tension and parts which are loose! :D

LukeW
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Joined: Mon Mar 03, 2003 1:14 pm

Post by LukeW » Thu Aug 14, 2003 12:59 pm

ilac wrote:I think its more an issue of added control in what is ultimately a virtual world! Being able to vary stiffness might be handy to represent parts of cloth under tension and parts which are loose! :D
If you can attach parts of the cloth to objects - to make curtains and hammocks, etc, this stiffness due to tension should automatically appear - rather than having the person paint it on.

ilac
Posts: 131
Joined: Mon Oct 14, 2002 8:24 am

Post by ilac » Thu Aug 14, 2003 1:22 pm

LukeW wrote:
ilac wrote:I think its more an issue of added control in what is ultimately a virtual world! Being able to vary stiffness might be handy to represent parts of cloth under tension and parts which are loose! :D
If you can attach parts of the cloth to objects - to make curtains and hammocks, etc, this stiffness due to tension should automatically appear - rather than having the person paint it on.
The key words should have been added control in what is ultimately a virtual world. At the end of the day its still not real, and would probably require manual tweaking. Even the hair on pixar's 'Sully' from 'Monsters inc' needed some manual tweaking in certain places. These automating plugins will handle the bulk but they still need touch-ups at times. Its not the real world - you cannot cater for every possible contingency. Theeths suggestion would help for that tweaking.

LukeW
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Post by LukeW » Thu Aug 14, 2003 1:48 pm

ilac:
I wasn't saying that stiffness painting shouldn't be a feature... I'm saying that it could be optional for the user since they mightn't use it (assuming that it can already use gravity to make hammocks ok) and if it was turned off it would probably make it quicker to calculate the cloth so that people can tweak the settings (like the overall stiffness of the cloth) quicker.
Now that I think of it, painting the stiffness would be good for making realistically creased materials - when materials have been folded, they tend to bend at those places (their stiffness is less at the folds). So people could paint where the folds hypothetically were. Some materials don't leave creases though... particularly some artificial materials... and silk I think. The user would need to keep that in mind. Other things like cardboard have a highly variable stiffness depending on the creases....
There are probably other reasons why painting stiffness would be good, but I think the stiffness due to tension should be automatically calculated by the code... (assuming you can attach the cloth to things - that is what you need to do in order to have tension...) Though of course, people could paint on their own unrealistic tension effects if they wanted to. Though stiffness due to tension can change over time... e.g. if a ball rolls down a hammock, the stiffness in areas of the cloth would change. That assumes that there is a physics engine there though...

theeth
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Post by theeth » Thu Aug 14, 2003 4:52 pm

Timothy wrote:it's a good faint!

Though I would also like some more control than just vertex paint,..
/me points at the armature weight system
Of course!

Who said we couldn't even reuse vertex group and weights.

Martin
Life is what happens to you when you're busy making other plans.
- John Lennon

ilac
Posts: 131
Joined: Mon Oct 14, 2002 8:24 am

Post by ilac » Thu Aug 14, 2003 8:19 pm

LukeW wrote: That assumes that there is a physics engine there though...
..fingers crossed... :wink:

TorQ
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Joined: Wed Jan 29, 2003 2:03 am

Post by TorQ » Thu Aug 28, 2003 9:01 pm

Here is recent paper on cloth from Pixar. It was shown this year at Siggraph.

http://www.pixar.com/companyinfo/resear ... ngling.pdf

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