Comments on: simutils-0001: Diffusion limited aggregation

By: Devin

Devin — Sun, 03 Apr 2011 06:02:30 +0000

Thanks! That helps a lot. One other thing… is there a way to export the octree cubes? I have tried to write something similar to your code you posted above, but it seems like I would have to convert all of the box data over to points, then reformat, and write a new function to format each of the boxes to export as 6 faces made up of 4 points. (This might be easier to do as points, but I was thinking maybe you would know how to link this with your geometry library classes, to export as an obj).

Thanks for your help!

Devin

By: toxi

toxi — Fri, 01 Apr 2011 08:09:36 +0000

Devin, of course there is (and it’s also shown in the code above). The following line creates the root node of the octree from XYZ=100,200,300 and expanding 100 units along the positive axes. So the max point of that cubic tree space will be at XYZ=200,300,400:

PointOctree octree = new PointOctree(new Vec3D(100,200,300),100);

Hope that helps!

By: Devin

Devin — Thu, 31 Mar 2011 20:11:43 +0000

Is there anyway to define the coordinates of the initial octree box, in order to reference the DLA simulation to another series of geometry? I am trying to generate some guide curves on a landscape and have the DLA grow along those curves. Thanks!

By: midterm proposal | angela chen

midterm proposal | angela chen — Sun, 08 Aug 2010 14:07:50 +0000

[...] Toxi recently posted about a library called simultis which explores this DLA process with some amazing looking results: http://toxiclibs.org/2010/02/new-package-simutils/ [...]

By: lifephysic

lifephysic — Wed, 07 Jul 2010 20:09:57 +0000

Have you taken in account magnetic field influence on the grown and many centers dla

By: DieTapete

DieTapete — Wed, 24 Mar 2010 03:04:28 +0000

I did some tests and wrote the values down for reference:
http://www.flickr.com/photos/dietapete/sets/72157623556675973/

..just in case someone’s interested in it.

By: toxi

toxi — Mon, 01 Mar 2010 21:34:40 +0000

Colin, merci beaucoup! The exported file is a raw Java DataOutputStream of XYZ coordinates of all points, nothing else. The source for the current export method is here:

http://code.google.com/p/toxiclibs/source/browse/trunk/toxiclibs/src.sim/toxi/sim/dla/DLA.java#220

Incidentally, this is the same format used by Sunflow for its “particles” primitive, but it’d be trivial to export this as anything else, e.g. like this:

// save particles as text file, 1 per line
void savePoints(DLA dla, String filePath) {
  try {
    FileOutputStream fs = new FileOutputStream(filePath);
    PrintWriter printer = new PrintWriter(fs);
    for(Iterator i=dla.getParticles().iterator(); i.hasNext();) {
      Vec3D p=(Vec3D)i.next();
      printer.println(p.x+","+p.y+","+p.z);
    }
  } catch (Exception e) {
    e.printStackTrace();
  }
}

Are there any standard file formats for point clouds I should know about/support? What are you guys using at Pixar for such things, i.e. how does Renderman handle point clouds (directly)?

It’s a true honour to have you as a reader, would love to see what you come up with! :)

By: Colin Thompson

Colin Thompson — Mon, 01 Mar 2010 20:07:23 +0000

Awesome!

Thanks for this. Super helpful. One question though: what file format are you using for your point cloud output? Is it sunflow specific? I’d like to use the data elsewhere.

thanks,

colin

By: uberVU - social comments

uberVU - social comments — Sat, 20 Feb 2010 12:43:16 +0000

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