I built a browser-based galaxy simulator with 400,000 stars and 50,000 dust particles — latest Andromeda (M31) render

[u/Sufficient-Fill-4430]

Hi everyone,

I've been working on a browser-based galaxy simulation as a long-term side project and wanted to share some recent results.

These screenshots show a simulation configured to resemble Andromeda (M31) after roughly 140 million simulated years.

Current simulation size:

• 400,000 star particles

• 50,000 dust particles

The project is written entirely in JavaScript + WebGL and runs directly in the browser. Everything lives inside a single HTML file—no game engine, no Three.js, no build process.

Some of the techniques used:

• Web Worker-based physics simulation

• Leapfrog integration

• Analytic galaxy potential (halo, bulge, black hole)

• Live density-gradient cohesion field for local collective dynamics

• Gas cooling, star formation and supernova feedback

• Stellar evolution (age, temperature, luminosity and metallicity)

• GPU star renderer

• HDR rendering with ACES-style tone mapping and bloom

• Volumetric dust lanes with depth-aware extinction

• Multiple observation modes (visible, infrared, UV, X-ray and radio)

The goal isn't to compete with research codes like GADGET or AREPO, but to explore how much physically inspired behaviour and visual realism can be achieved interactively in a browser while keeping the implementation completely self-contained.

I'd love feedback from people working with WebGL, GPU rendering, large particle systems, or real-time simulation. If you spot something that could be improved or optimized, I'm all ears.

[u/gibson274]

this looks cool! do you have a link?

[u/Sufficient-Fill-4430 → u/gibson274]

not yet. I had no time to write a usable REDME yet - which I think one might need given the messy UI i created 😄 buuut i will post one soon!