snek is a simple data structure for working with vertices and edges. More
importantly it is a programming pattern for applying changes to the structure.
It is specifically written to be useful for a broad range of ways in which I
usually write generative algorithms for creating art.
A while back someone on twitter suggested that if Python 3 was named "snek" it would avoid naming confusion. I found that amusing at the time, and picked snek as the placeholder name for this project. I've been looking for a better name, but I haven't found one yet.
The pattern depends on the concept of alterations. In short: an alteration
is a change that will be applied to the structure at the end of a given
context. alterations are further described in
http://inconvergent.net/snek-is-not-an-acronym/.
I have also written about things related to snek at
- http://inconvergent.net/a-propensity-for-mistakes/ (indirectly about
snek) - http://inconvergent.net/a-method-for-mistakes/
- http://inconvergent.net/arbitrary-alterations/
- http://inconvergent.net/grains-of-sand/ (about "sandpainting", see
src/sandpaint.lisp)
Here is and example of manipulating a snek instance called snk using
alterations. Alteration constructors are postfixed with ?.
; context start
(snek:with (snk)
; iterate vertices
(snek:itr-verts (snk v)
; move alteration
(snek:move-vert? v (rnd:in-circ))
; w will be an arbitrary
; vertex in snk
(snek:with-rnd-vert (snk w)
; join v and w if they are closer than d
(if (< (snek:edge-length snk (list v w)) d)
; join vertices alteration
(snek:join-verts? v w))))
; context end
; alterations have been appliedYou can define your own arbitrary alterations. There is an example of this in
ex/custom-alt.lisp. I have also written about it here:
http://inconvergent.net/arbitrary-alterations/
There are some examples included. All examples are in the ex folder.
if you don't provide a result name as the first argument, then the resulting
file will be named tmp.png.
This includes a few samples of how to use the plotting functionality. This will export a simple vector file and an image to indicate the result.
snek is used in
- http://moment.inconvergent.net/
- https://twitter.com/sandpaintbot
- https://twitter.com/scratchpaintbot
- https://twitter.com/cronianrings
This code requires Quicklisp and zpng. The path to quicklisp must be set in
src/load. zpng is automatically installed via quicklisp.
There are some tests included, see the test folder.
This code is highly experimental on my part. It is likely to change with no
warning or explanation. I will keep a note of the version number in
src/load.lisp.
This code is a tool that I have written for my own use. I release it publicly in case people find it useful. It is not however intended as a collaboration/Open Source project. As such I am unlikely to accept PRs, reply to issues, or take requests.
- Randomized order of alteration apply
- one-ring/ incident edges
I would like to thank
Who have provided me with useful hints and code feedback.