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aatish

Re:Drape – a Fabric Simulator on Saturday June 04, 2016 @11:03AM (#11836559)
Haha nice! Try that in wire-frame mode and it looks even crazier: https://twitter.com/aatishb/status/727270083601551360

I left that in as allowable behavior, because our goal with this was not necessarily to model a realistic cloth but more to experience interesting and unusual movements and behaviors. So glitch away!

Re:Drape – a Fabric Simulator on Saturday June 04, 2016 @10:59AM (#11836551)
I'd started off this project by using a fancier ray-tracing method of detecting and avoiding collisions with arbitrary shaped objects. Unfortunately it was just too slow for satisfying real-time performance. So finally, I went with doing the collision detection in a case-by-case way for more simple shapes (ball, table, etc.). The poles would be easy to add as an option, I may try to add that in. Thanks for the suggestion!
Re:Drape – a Fabric Simulator on Saturday June 04, 2016 @10:46AM (#11836502)
Yup, that setting is implemented in a somewhat naive way. The way it works is that I iterate through every pair of points on the cloth, check for when they get too close, and if they are, I introduce a spring to push them apart. So effectively this introduces a short-range repulsive force between pieces of the cloth.

Avoiding self intersections results in more realistic cloth behavior like folds and wrinkles. The problem is, iterating through all pairs of points comes at a computational cost, and can really drop the frame-rate, particularly for large cloths. So I decided to keep this setting off by default until I have a smarter way to implement this (e.g. using quadtrees).

Re:Drape – a Fabric Simulator on Friday June 03, 2016 @05:00PM (#11833245)
Hi, thanks for voting this up! I created this with a few colleagues. Our goal was to make a fabric simulation tool that might inspire creative exploration among artists and engineers. I hope you find it fun to play with, and welcome any feedback and suggestions on how to improve this.

We started from a three.js cloth simulation example and made a bunch of modifications. The cloth is modeled as a grid of point masses (particles) connected by springs. We've got options for horizontal & vertical springs (simulating cross grain, where the cloth threads run parallel to the edges), diagonal springs (simulating bias grain, where the cloth threads run diagonally), and springs that connect particles two units apart (simulating drape / bending stiffness, similar to a starched tablecloth). It's kind of amazing how a simple system of particles and springs can result in such rich cloth-like behavior. Other than the springs (which are modeled as constraints on the distance between particles), the only forces on the particles are wind and gravity. In addition we have constraints that account for collisions and simulate friction-like behavior.

We've submitted a paper that explains the details of how this works which I'll share once it's published, but for now if you're interested in learning more here are a few references, or google 'verlet integration constraints'. Also happy to try to answer your questions.

https://graphics.stanford.edu/~mdfisher/cloth.html http://www.pagines.ma1.upc.edu/~susin/files/AdvancedCharacte... http://kucg.korea.ac.kr/education/2005/CSCE352/paper/provot9... http://luthuli.cs.uiuc.edu/~daf/courses/Games/SimList/Papers...

Re:Show HN: Drape – a Cloth Simulator on Thursday May 05, 2016 @06:45PM (#11640257)
Built starting from the Three JS cloth simulation example. Our goal is to create a fabric simulator that can serve as a tool for artistic exploration and expression. Would appreciate any feedback.
Re:How Insects Breathe on Friday November 13, 2015 @03:36PM (#10562249)
The issue, I think, is that experiments like that would only tell you so much, because the insects aren't adapted to the high levels of oxygen (which can be kinda toxic, particularly at higher concentrations). So to really understand this you'd need to breed insects in high oxygen over many, many generations, and have them evolve in this new environment. That takes a lot of time and money. Jon's lab has done it with fruit flies, and they do grow bigger over the generations. But as far as I know (which isn't a lot), folks haven't done those kinds of multi-generation experiments in many species.
Re:How Insects Breathe on Friday November 13, 2015 @12:42PM (#10561132)
Yup, we also have another post that's specifically about the idea you describe: http://noticing.co/on-size-and-warmth/
Re:How Insects Breathe on Friday November 13, 2015 @12:07PM (#10560905)
Great question!

We spoke to Jon Harrison about this (the scientist we interviewed who studies insect growth & respiration). He says that the truth of the matter is we don't know the answer, it's still a hypothesis that the way insects breathe keep them small. There are other competing explanations, like that it's insect's exoskeletons that constrain their size, or ecological arguments (fewer predators means they can grow bigger). Also spiders don't use trachea to breathe but are also small.

One piece of evidence favoring the oxygen hypothesis is research that shows that the fossil record on giant insect size correlates with the oxygen levels in the past, all the way up until birds evolved (and wiped out the ecological niche for giant flying insects!)

http://blogs.discovermagazine.com/notrocketscience/2012/06/0...

And I'm told there's some more interesting work along these lines that's yet to be published.. so hopefully we should know more soon.

Lastly, there's all kinds of experimental work on breeding insects in high oxygen environments, but the results so far aren't universal.. some kinds of insects grow bigger, other's don't. The idea being that oxygen can help the insect grow but can also do damage to cells (in a way similar to aging), so you may need a long while to evolve and adapt to higher oxygen levels.

Re:How Insects Breathe on Friday November 13, 2015 @08:30AM (#10559710)
Hi, I'm one of the authors of the piece. Thanks for voting us up here. Hope you like what we're doing, and let us know what you think. If you're looking to read more of our posts, you can follow the blog on twitter @noticingblog (or on RSS). Cheers.

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