A halftone post effect. It turns a picture, a video or a whole 3D scene into printed dots: each dot grows with the ink its tone needs, on a turned screen, with anti-aliased edges at any size. Use two inks for a duotone, or three overlapping cyan, magenta and yellow screens at the classic angles for a colour print look.

With no picture it screens a small moving scene of its own, a sun, rolling hills and a floating heart, so the demo and the video work straight away. Set the ink and paper colours, dot spacing, screen angle, contrast and dot softness. The demo has three presets: Indigo on blush, Berry on cream and CMY print, and a button to try it on a picture from your computer.

What you get: a GLSL ES 3.00 fragment shader for plain WebGL2, an ES module that returns a three.js ShaderMaterial (pass your texture as an option), a Shadertoy version that reads iChannel0, and a demo page that runs offline. There is also a 10-second 1920 x 1080 H.264 loop of the test scene in dots.

It runs in one pass, at about 1.2 ms of GPU time per frame at 1920 x 1080 on a recent laptop. The README covers wiring up your own images in each version, every uniform with its default and range, and performance notes.