Arbitrary-dimensional fast diffusion-limited aggregation simulator
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README.md

dla-nd

An arbitrary-dimensional diffusion-limited aggregation simulator. See some images and more at (http://markjstock.org/dla-nd/)

Features

dla-nd supports the following features

  • Automatic, persistent, adaptive 2^D-tree space subdivision
  • Statistically-correct particle motion bias (bulk motion) numerically solves quartic equation each step
  • Stubbornness (Nittman and Stanley's artificial surface tension model)
  • Tunable stickiness and grippiness
  • 2-d or 3-d density field construction
  • Raw, Radiance, and generic OBJ output for particle positions and connectivities
  • PNG and ASCII PGM output for particle locations and density field
  • Restart from an old simulation, or merge multiple simulations using raw .part files

Building the software

In the directory that this file is in, just type

make

and several binary executables will be made. If you want to build a specific executable for 1D through 5D, just type

make dla-5d

replacing the 5 with 1, 2, 3, or 4, when appropriate. If you want to build an executable for higher dimensions, you'll need to edit the structs.h file and add your own code.

Usage

Edit the sample.dnd file, making sure to match all coordinate input with the number of dimensions in the problem.

Unix users can then run the desired program as shown:

dla-2d sample.dnd
dla-2d < sample.dnd

Windows users have several options. You can drag the .dnd file onto the appropriate .exe file, whereupon the output files will either appear in the current working directory, or your home directory (which in my case was C:\Documents and Settings\mstock).

You can also run "cmd" to enter the DOS-like command prompt. From there, you can run

dla-2d.exe sample.dnd

Lastly, you can download and install MSYS, a Unix-like environment, and run the program from within MSYS using

dla-2d.exe sample.dnd
dla-2d.exe < sample.dnd

If your .dnd file is set up to read in another file, you need to make sure that the other file is in either (or both) your current working directory or your home directory. As a windows novice, this confused me.

Advanced use

Feel free to monkey with the code. If you look in the Makefile, and the first part of structs.h, you'll quickly see how to make executables that can track ANY number of dimensions. So, if you want to run a 27-dimensional DLA, all you need is a large-enough computer.

Change Log

v1.1 Chiral growth

v1.0 Windows and Linux executables included

v0.9 includes timer, line-at-a-time statistics file, constantly- overwritten pnd output file, random seed much faster due to elimination of slow and unnecessary routine

v0.8 fixed bulk motion algorithm; now uses numeric root-finder to determine actual dt for diffusing particles added experimental rotex growth using source/sink/vortex influences

v0.7 added libpng support, removed GIF support and related system calls added bit depth parameter to output file merged image_size and density pixel sizes---all output images use image_size now fixed bounds on sim-> construction variables fixed moving_particle problem in replace_all_particles() allowed automatic resizing of tree to accommodate all particles

v0.6 upgraded dla3d to dla-nd other minor improvements