DigitalWork Instructions

The problem

A STEP assembly of a small aircraft is tens of megabytes of exact geometry. Browsers can't show that quickly, and operators don't need exact B-rep surfaces; they need to see which part goes where, in what order, with which tool.

Approach

1. Convert once, at build time. OpenCASCADE (WebAssembly) tessellates the STEP file; the model is centred, rotated to Y-up and split by face colour so each part keeps an ID.
2. Compress hard. glTF-Transform deduplicates, welds and simplifies meshes, then applies quantisation and meshopt compression.
3. Describe steps as data. A small rules file groups parts into steps and gives each one text, tools, a check, an approach direction and a camera view.
4. Make time the single source of truth. The whole animation is a pure function of time, so the slider can scrub forward and backward and every frame is reproducible.
5. Design for the workbench. Shop-floor mode shows one step at a time in large type, with swipe and keyboard navigation.

Results

• 73 → 0.9 MBmodel size
• ~1 MBwhole site, gzipped code incl.
• 57 / 11parts / steps
• 0console errors in click-through tests

Tested with scripted real clicks (play, pause, step jumps, shop-floor mode, exit) and on phone-sized screens. The viewer also recovers if the browser drops the graphics context.

What I'd do next

• Author steps visually in the browser instead of in a rules file.
• Add fastener callouts and torque values as data on each step.
• Offline install as a PWA for tablets without network access.
• Let an AI agent draft step text from the part tree, with a human approving every step.