# occt-shape-viewer

**Repository Path**: daoos_admin/occt-shape-viewer

## Basic Information

- **Project Name**: occt-shape-viewer
- **Description**: step模型比较
- **Primary Language**: Unknown
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2026-03-23
- **Last Updated**: 2026-04-02

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# OpenCascade Visualizer

Browser-based CAD shape viewer using [opencascade.js](https://github.com/nicholasgasior/opencascade.js) (WASM) and [Three.js](https://threejs.org/).

Loads STEP (.step/.stp) and BREP (.brep/.brp) files entirely client-side — no server required.

## Features

- **STEP/BREP file loading** — drag-and-drop or file picker
- **Full topology tree** — Compound → Solid → Shell → Face → Wire → Edge → Vertex
- **3D visualization** — per-face mesh rendering with orbit controls
- **Click selection** — click in 3D or tree to highlight shapes and view properties
- **Large model support** — models with 200+ faces use merged geometry (single draw call) with vertex-color highlighting
- **Properties panel** — displays area, length, volume, coordinates per shape type

## Tech Stack

- **OpenCascade.js** v1.1.1 — OCCT 7.4 compiled to WebAssembly (~63MB)
- **Three.js** v0.183 — 3D rendering
- **Vite** v7.3 — dev server & bundler
- **TypeScript** — vanilla, no framework

## Getting Started

```bash
npm install
npm run dev
```

Open http://localhost:5173/ and drop a STEP or BREP file onto the viewport.

## Project Structure

```
src/
  occ-loader.ts      — WASM module loader
  step-reader.ts      — STEP/BREP file reader (Emscripten VFS)
  topo-explorer.ts    — TopoDS_Iterator-based topology tree builder
  mesh-builder.ts     — OCCT → Three.js mesh conversion (per-face & merged)
  viewer.ts           — Three.js viewport, controls, raycasting, highlighting
  topo-tree.ts        — Topology tree panel UI
  properties-panel.ts — Shape property display
  main.ts             — Application entry point
  style.css           — Dark theme styling
```

## Architecture Notes

- STEP files are written to the Emscripten virtual filesystem as `Uint8Array`, then read by OCCT's `STEPControl_Reader` using bare filenames (no leading slash)
- All WASM C++ objects are tracked via `ShapeRegistry` and explicitly `.delete()`d to prevent memory leaks
- Shapes from `TopoDS_Iterator` must be downcast (`oc.TopoDS.Face_1()`, etc.) before passing to `BRep_Tool` methods
- Models exceeding 200 faces are rendered as a single merged `BufferGeometry` with vertex colors for per-face highlighting

## License

MIT