🎨🎲 Reproducible procedural drawing tool (pre-alpha)
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Latest commit e83d814 Aug 22, 2018



This project is not in development, but I have ideas about how the problem(s) could be solved more generally. See Mopaint

Pixelweaver is a reproducible procedural drawing tool.

It lets you scrub through time, without restricting you by saying your drawing code has to be a function of time (or of some small state object). (It shows you a preview, and when you release your mouse button it simulates from the beginning up to that point. Having your drawing code as a pure function could be an alternative option (retained mode), to make jumping to any point in time equally unexpensive.)

Images saved with the Export button can be loaded back into the app with drag and drop and you can play back to the point the image was captured. And beyond. Or back. Maybe try a new random seed. And you can save other screenshots, which will also embed all the data needed to reproduce them.

Warning: loading a program (including via screenshot) is totally unsandboxed for now! (But as long as it's your own code you're loading, you don't have to worry about that.)

Pixelweaver is currently focused around an immediate mode drawing paradigm on a 3D canvas in contrast to the usual retained mode for 3D, such as with a scene graph.

It could be expanded to allow for retained mode 3D as well, maybe even VR. Other possibilities include 3D and 2D repeating patterns and tessellations by wrapping drawing calls and transforming and duplicating them, as well as plain old 2D.

The app lets you scrub through an animation, simulating up to that point when you release.

When you take a screenshot with the Export button, it embeds all the metadata required to reproduce the state, including the entire source code for the program, the position in the animation, the random seed, the viewport (camera), and any other inputs. It'll also include the Creation Time (time of export), and the Author if specified via an @author tag in the source. There are a few other standard metadata keywords like Title and Description that could be supported as well.

You can drag an exported file back onto the app to load up the program. Note that this is totally unsandboxed for now, and there isn't a reasonable way to preview a program's code before running it.

You can also drag a source code file onto the app to load. (Unsandboxed.)

Since the viewport is an input to the program, I could let you zoom around with the UI, previewing the change by scaling/translating the output of the program before simulating back up to that point.

I could render the program in parallel at a zoomed out scale (at a lower resolution), and use that for the preview when zooming out or panning, and potentially a minimap for navigation as well.


For now, these are the steps you need to take to play around with it:

  • Install a reasonably recent version of Node.js if you don't have it already
  • Clone the repo
  • Open a terminal/command prompt
  • Run npm install
  • Then you can run npm start, which will start up a server and open up a page in your browser which will reload when you edit the program, or make changes to Pixelweaver itself.

You can change the default program that's loaded from examples near the bottom of app.js. Programs are currently written in Coffeescript, because I like CoffeeScript. Ultimately you should be able to use JavaScript or any language that compiles to it.

Don't forget to put your name in the @Author line.
(You could leave mine and do a + if you want, based on how much you've changed it or whatever, but you don't have to.)
(You can ignore helper functions because they're not important to the art.)
(Maybe the examples shouldn't have an @Author? But then they wouldn't be an example of @Author...)

Keyboard Shortcuts

Shortcut Action
R Reseed
E Export
Spacebar Play/pause
Home Seek to start
Left arrow Seek backwards (Note: recomputes up to that point!)
Right arrow Step forwards
,/< Step backwards one frame (Note: recomputes up to that point!)
./> Step forwards one frame

(The shortcuts for single-frame stepping also work on YouTube by the way.)


The API isn't exactly solid yet. But it's versioned, at least.

There are way more use cases for the functionality than I initially considered. Probably need to invert control somehow to allow for these possibilities.

At the top level, you can provide @draw and @update.

@draw is passed the gl object from lightgl.js.

(Note: lightgl.js isn't really made for this, and the immediate mode drawing functions are described as "only meant for quick debugging tasks" - but it's simpler than raw WebGL)

There are no requirements that a program's state be JSON-serializable. You can even update state in draw, but that should "really" be done in update. (If it feels natural to update state and draw at the same time, you can.)

You shouldn't use setTimeout or setInterval, Date or other timing functions. I could provide every and after helpers that operate on animation frame intervals. (But you can already do these things by keeping a time variable and checking equality for scheduling a single event, or time modulo N for a repeating event.)

And don't use global variables or localStorage or other obvious ways you could work around (i.e. break) reproducibility.