Simulation Viewer

3D simulation file viewer for VS Code. Open, inspect, and interact with VTK datasets directly in the editor.

Publisher: Nahiid Islam

What is Simulation Viewer?

Simulation Viewer is a custom editor extension for VS Code that provides an end-to-end simulation visualization workflow for .vtk, .vtu, .vtp, and .mph files.

It starts a local Python backend (FastAPI + PyVista), processes your dataset into render-ready polydata, and displays it in an interactive webview powered by vtk.js.

No external server is required, and the vtk.js runtime is bundled locally for offline use.

Features

One-click Visualization in VS Code

Opens supported simulation files directly as a custom editor
Integrated rendering viewport with orbit/pan/zoom interaction
No context switch to external tools

Local Backend, No Cloud Dependency

Automatically starts a local FastAPI backend from the extension
Uses PyVista to process and triangulate surface geometry
Works offline once dependencies are installed

Scientific Display Controls

Scalar field selector (point or cell data)
Colormaps: Rainbow, Viridis, Cool-Warm, Plasma, Grayscale
Custom scalar range min/max with reset
Clip plane with axis selection (X, Y, Z)
Opacity slider, bounding box toggle, axes toggle

Productivity Utilities

Screenshot export (PNG saved next to source file)
Dataset stats panel (points, cells, bounds)
Progress overlays for upload/process/load states

MPH Handling

.mph files are detected and marked as pending conversion
User-friendly guidance is shown to export from COMSOL to .vtk/.vtu

Getting Started

1. Install dependencies

npm install

2. Build extension

npm run compile

3. Run in Extension Development Host

Press F5 in VS Code, then open any supported simulation file.

Supported extensions:

.vtk
.vtu
.vtp
.mph

First Run Behavior

When activated, the extension:

Checks simulationViewer.pythonPath (if configured)
Falls back to its managed virtual environment if needed
Creates a private venv on first run and installs backend requirements
Starts backend on a free local port
Opens files in the Simulation Viewer custom editor

If a configured Python path is invalid, the extension auto-falls back and logs diagnostics in the Simulation Viewer output channel.

Extension Settings

Setting	Default	Description
`simulationViewer.pythonPath`	`""`	Python interpreter path. Leave empty for auto-detect/fallback.
`simulationViewer.autoStartBackend`	`true`	Starts backend automatically during activation.
`simulationViewer.keepTempFiles`	`false`	Keeps processed files for faster reopen/debug workflows.

Commands

Command	Description
`Simulation Viewer: Open in Simulation Viewer`	Opens selected or active supported file in the custom viewer.
`Simulation Viewer: Show Log`	Opens the extension output channel for diagnostics.

Project Structure

simulation-viewer/
├── src/
│   ├── extension.ts
│   └── SimulationViewerPanel.ts
├── media/
│   └── viewer.html
├── backend/
│   ├── server.py
│   ├── converter.py
│   └── requirements.txt
├── logo.png
├── package.json
├── tsconfig.json
└── webpack.config.js

Packaging

npm install -g @vscode/vsce
npm run build
vsce package

Troubleshooting

Backend failed to start

Open command: Simulation Viewer: Show Log
Verify Python path setting or leave it empty for auto fallback

vtk.js runtime failed to load

Rebuild extension (npm run compile)
Ensure dist/media/vtk.js exists after build

MPH file not rendering

Export from COMSOL to .vtk or .vtu
Reopen exported file in Simulation Viewer

License

MIT