120 points by smusamashah 11 hours ago | 9 comments
heyitsgarrett 5 hours ago
Oh thanks for sharing this! I love asesprite, procreate, pico8 and had this idea for programmable brushes bonking around my head for years now. Recently took some time between projects to put it together.

MOSS is a drawing toy where each brush is a tiny script that knows about every pixel on the canvas. You define how it paints with noise, randomness, patterns, stroke speed, pressure, and every touch executes the code.

So you can have a brush that scatters pixels like a real spray can or one that stamps shapes that mutate as you drag. Or perspective lines that actually converge. Or a fill bucket with smart gap awareness (I called it "Fill of my Dreams" and added to the brush list).

Happy to share brush code in the comments or explore ideas together. There's a (?) in the bottom right toolbar with API docs, and a prompt copy at the bottom if you wanted to work with the API through an agent.

azeirah 40 minutes ago
I wrote a program that has programmable brushes about ten years ago, it's a bit different from moss in that it has a physics simulation underneath rather than a sort of shader, but I've always thought this kind of approach has a lot of potential.

It feels _amazing_ to draw a bird in a single stroke!

Maybe this can give you some inspiration!

https://laura.fm/generative-art/wind/wind.html

vunderba 25 minutes ago
Very cool. Side note, but I've always thought that a combination of a pixel art editor like Aseprite coupled "cellular sand sim" would be really cool.
Lambdanaut 3 hours ago
I love how fun this is. It has so much personality. Definitely can see the pico8 and aseprite inspiration.

I think what could be really interesting is some procedural generation brushes... Like a brush that generates a random city-scape as you draw it. That sounds so exciting..

Maybe using wave function collapse:

> https://nathanmcoleman.com/projects/wavecollapse/

graypegg 23 minutes ago
That's such a neat idea! It's like a paintable version of https://www.shadertoy.com

Is there a way to share brushes in the app/a brush sharing gallery? For sharing, I can see the "weekly" section from the homepage, which looks to be a weekly art prompt and everyone's go at it, which is really fun! But for the more artistically challenged (myself), it'd probably want to share a brush on it's own haha

Klonoar 3 hours ago
This is amazing.

Could you add support for holding `Shift` to keep your line straight while painting, ala MSPaint?

RodgerTheGreat 3 hours ago
Moss looks much more general and powerful, but Decker has a similar mechanism for custom brush behavior; here's an interactive tutorial with a variety of examples, for comparison: http://beyondloom.com/decker/brushes.html
od0 3 hours ago
This is the most fun I’ve had drawing with pixels since I was a kid
mpalmer 3 hours ago
Absolutely lovely design, thanks for the share and the inspiration
adammarples 2 hours ago
In what way is a brush a program? How do I program it? I've spent 5 minutes and clicked on every single thing I can find but I give up looking.
boothby 11 minutes ago
It's way cooler on desktop than mobile.
heyitsgarrett 1 hour ago
If you hover next to the brush in the Edit mode as well, theres a tiny pencil icon there that opens that brush's code. Sorry it was hard to discover!
jammaloo 1 hour ago
Click "Editor", then click "Add a brush".
olivia-banks 2 hours ago
This is a seriously fun tool. Bravo!
zelez 11 hours ago
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