weekend hack: implicit.js an open source library that lets agents generate CAD with code + mathematical functions representing surfaces no CAD kernels, no STEP files just agents using math + code to directly generate 3D models details below!

what is implicit.js? a small library of SDFs with a browser-native renderer: a demo that renders 3D models from code in realtime: a set of skills to write code to generate 3D models with agents:

quick explainer on implicit CAD: vanilla CAD = “draw this surface, extrude it here, trim it here, join it to that edge” implicit CAD = “this is a field/rule; the part exists where the rule says it exists” basically, implicits model 3D objects with mathematical rules that define surfaces

some awesome things about implicits: - no CAD kernels (parasolid, opencascade, etc): the math + code is the model - they are FAST: the demo compiles and renders models from GLSL in the browser in realtime - representations are small: implicit code can be 100x smaller than STEP files

implicits are great at: - manipulating complex geometry - producing high resolution, scaled cad models - boolean / offset operations but they are really hard for humans to intuit, which is why we prefer vanilla CAD that works more like LEGO: faces, edges, holes, cuts, fillets, etc, with human-readable topology

agents on the other hand are very, very good at coding and math, the two key ingredients for implicits the third ingredient is visual / spatial reasoning while lacking today, I believe for many reasons (including robotics) this will be the next frontier that labs pursue

to caveat: agents aren’t great at implicits today frontier models are still pretty blind, so implicits break down on complex parts/assemblies with visual feedback (code -> model -> screenshot -> repeat) there is also no easy toolchain to inspect implicits because they lack topology

that said, 6 months ago the models couldn’t write reliable code things are changing fast, and I think 2026 will be the year the models solve 3D design i also think it's possible (and even probable) that implicit CAD becomes the preferred way for models to do 3D design

special thanks to @bcourter and the Gradient Control team for teaching me about implicits and sharing the python primitives used to build this library Blake is the GOAT of implicit CAD and gave an excellent talk on this exact topic at Kinetic a few weeks ago

Yo... @AndrewASink this feels like something you would very much appreciate.

You're a grinder Jake. You doing this for a living or a hobby?

i'm just extremely nerdsniped by cad right now

'nerdsniped' 😂😂😂 I don't think it's a coincidence that you're addicted to connecting the foundational OG 'world-builder' with epochal tech @threejs This compulsion is what futures are built on, and you feel it in your gut. No pressure, just keep following that feeling.

yes no step files changes how models build geometry

mermaid js implicit js three js

the honest answer is that implicit.js is a game-changer for agent-based design, allowing them to skip cad kernels and step files altogether. it's all about using math and code to generate 3d models directly.

This is great man. Thanks for developing it.

Do everything in the web browser using JavaScript, exactly.

@threejs Wonderful! 🔥🔥🔥🤗

@earthtojake I wonder how long before it is possible to generate and edit 3d models etc

it’s possible today !

@earthtojake for example would I be able to generate a car edit it etc or basically use this as a replacement for blender

This looks amazing! Might need to add it to what I’m building