Something I’ve been thinking about doing for a long time is imitating real artistic media, in particular watercolours. Not because I’m an avid watercolour painter (last time I’ve touched them was in kindergarten), but because I think it’s an interesting dynamic. Since it is mainly fluid dynamics, the idea resurfaced after my previous fluid sims. And luckily, with Pixel Bender, I can finally do this kind of thing! This paper by Cassidy J. Curtis et al was great, tho it also caused me to loose some time figuring out some errors. Finally I came up with something, dubbed Farbe (simply German for ‘colour’). One thing I dropped was the interaction between different strokes, because that would kill the cpu easily enough.
For a change, there’s no source of this, and for a few reasons. First of all, it’s a mess and needs to be optimized. Apart from that, I might just add on to this before I release anything (hence the project name ‘Farbe’).
The picture on the left is my poor imitation of Joan Miró’s Barcelona ’92 poster (Strepie, this one’s for you 
), so ignore that and create your own 
Zeh
on Feb 17th, 2009
@ 12:31 am:
Amazing. Amazing. I had planned to study fluid dynamics a while ago for some shader work I wanted to create but in the end resorted to some basic image manipulation due to lack of time, so seeing something like this is quite inspiring to get back to it. Also, thanks for the references!
Ryan Taylor
on Feb 17th, 2009
@ 6:04 am:
Very nice!
sakri
on Feb 17th, 2009
@ 7:00 am:
whatever happened to the weeks of failure you promised? That was just last week
Stunning!
Strepie
on Feb 17th, 2009
@ 9:00 am:
Much appreciated! Those who were there remember. Barcelona ’92, the day the earth stood still.
Kristof Van Roy
on Feb 17th, 2009
@ 9:41 am:
Impressive! Nice work!
Steven Verbruggen
on Feb 17th, 2009
@ 11:04 am:
Really cool!
Let’s Digg the mofo! http://digg.com/design/Farbe_Watercolour_simulation
Alain
on Feb 17th, 2009
@ 11:59 am:
Well done chap!
“Ik ben blij dat je in mijn team zit”
David
on Feb 18th, 2009
@ 11:15 am:
Zeh: Fluid dynamics is definately worth checking out. I’ve been getting into it a couple of months ago and I keep getting back to it in some way; there’s endless possibilities to be explored
Sakri: Correction, TWO weeks ago!
Back then it was all in abstract form and not quite working as it should. Luckily the breakthrough came sooner than expected 
Strepie: Never forget Cobi, the Catalan Sheepdog!
Steven: Yeah baby, my first digg! Thx
Ryan, Kristof, Alain: Thanks
Mark
on Feb 19th, 2009
@ 12:05 pm:
Wow, you can create some really cool fire effects as well by continuing to paint orange in the same spot! Good work!
Pierre
on Feb 19th, 2009
@ 3:18 pm:
Nice indeed! What about the source?
David
on Feb 21st, 2009
@ 3:53 pm:
Mark: The ‘fire effect’ is actually the result of physically incorrect mapping of the pigments to the composited layer. I’ll be investigating that however, so if all goes well, we’ll be loosing that nifty “feature”, so enjoy it while it lasts
Pierre: I’m thinking of moving Farbe out of the experimentation state and into a proper project. As such, I’m not sure what I’ll do with the source yet.
localToGlobal » Blog Archive » news review -> 8th week of 2009
on Feb 25th, 2009
@ 12:40 pm:
[...] > Flash watercolour simulation (using PixelBender) | Der Schmale – David Lenaerts’s blog [...]
Flash Friday - 3D Trails, Flash Blackholes, Pixel Bender Watercolor and Much More | Weber Design Labs
on Feb 27th, 2009
@ 7:42 pm:
[...] Water Color with Pixel Bender http://www.derschmale.com/2009/02/16/flash-watercolour-simulation-using-pixelbender/ [...]
Jean
on Apr 9th, 2009
@ 3:53 pm:
Great soft Merveilleux !!! I’ve just try it I’m not an artist but I love watercolour.
Many thanks from France.
Jean
St
on Apr 12th, 2009
@ 12:41 pm:
There’s something wrong in code. When you click inside your canvas and drag your stroke outside canvas at the top of the image your strokes and/or texture starts to disappear. I.e. try to paint uniform blue sky using long wide strokes (high water size and pigment size) from left to the right side of the canvas (going slightly outside). And you’ll see banding artefacts or top of your stroke will disappear while calculating (this applies to all systems linux/win I tried it on).
David
on Apr 12th, 2009
@ 12:43 pm:
Yes, that’s still a bug in this version. The new version of Farbe doesn’t have that issue anymore, but I can’t say yet when it will be released
Image bleeding with water (Flash + PixelBender) | Der Schmale - David Lenaerts's blog
on Apr 13th, 2009
@ 10:25 pm:
[...] of the things lacking in the watercolour POC was that once a brush stroke was made, nothing could be done with it. I thought it’d be nice [...]
buyung widhi
on Oct 15th, 2009
@ 8:04 am:
hi, just want to let you know it seems that somebody already create a full application based on your idea.
check this out :
http://www.replay-your-fragrance.com
now, about the source, any chance we could see it anytime soon.
cheers, mate.
David
on Oct 15th, 2009
@ 8:56 am:
Yep, I’ve seen that site
Similar idea but completely different implementation. About the source, I can’t say yet. Farbe has grown immensely in scope and first I want it released (it’s still being worked on), I’ll worry about source later. But I’m still not sure whether it will/can be released as open source or not.
Dany
on Feb 21st, 2010
@ 5:07 am:
It will be great to see “Farbe”, the watercolor simulation,
as a real functional application,
the demo page is the best I know comparing to the programs
that I actually use.
I saw an image of the program that you published,
isn’t possible to make available a beta Farbe
until you deal with the stains ?
I am sure many will be happy with that.
David
on Feb 21st, 2010
@ 4:48 pm:
Dany: A little more patience
I’m working towards a beta, even tho it’s going a bit slower than I expected. However, I need to fix some loose ends which are too important!
Mathieu Gosselin
on Mar 19th, 2010
@ 5:09 pm:
Very nice!
That would be good to have it painting in real time thought. Waiting to see the result is a little bit frustrating. I am looking myself to do some 3D impasto painting thing for my little photopainting software. Do not stop there, i’d like to see an optimized version of it!
Mary
on Jun 27th, 2010
@ 1:38 am:
This is great!
I am looking for help in rendering just the watercolor and fluid dynamics of this, without the controls and without the mouse involvement. Can you point me in the best direction to get started?
Great work and we all await your app!
Cheers, Mary
David
on Jun 27th, 2010
@ 11:58 am:
Hi Mary,
The article mentioned in the post is the best way to figure out how it works. It involves quite some math, but you’ll have to deal with that in any case!
Cheers,
David
Kristen
on Dec 17th, 2010
@ 9:11 pm:
Hi, I just discovered this, and this is amazing – on so many different levels – the math behind it, the physics of fluid dynamics, the watercolor look, etc. As watercolor is my medium of choice, I have been looking for something like this for the iphone/ipad and there is nothing at all like this!
All good things need lots of work and attention and that is obvious in this case, but do you have some kind of time line in mind for when this will come out? (Also, I am assuming that since this uses flash, this won’t be available on the ipad, which is a real bummer, which is apple’s fault).
Well, great work! So cool!