I Simulated 2 Million Celestial Orbits in Real Time

I was curious just how many celestial orbits I could simulate in real time. So, I started with a special little star called the Sun and its planets to make sure everything worked properly. Then I added stars and planetary systems until the simulation finally began to struggle. Turning to burst-compiled parallel jobs allowed me to push much further, eventually reaching 2 million simulated orbits running in real time at 60 frames per second. Not a Milky Way by any means, but a fun-sized pocket galaxy at least. We will base our orbit simulations on the real world, or rather the real universe. We can’t have both realistic distance scales and realistic volume scales. If the Earth was scaled to a single pixel, the Sun would be 109 pixels wide, but would need to be almost 11 thousand pixels away from the Earth. So, we’ll have to oversize our smaller celestial bodies visually, but we’ll use the correct distance and mass values in the calculations, so that the orbits are realistic. This is the story of implementing what I've learned into a gridless, interactive, world-building sandbox game called Minor Deity. Minor Deity on Steam: https://store.steampowered.com/app/3876240/Minor_Deity/ Minor Deity Discord Server: https://discord.gg/2NEb4HxwhF 00:00 Introduction 00:35 Scale 01:00 Eccentric Orbits 03:13 Orientation in 3D Space 03:42 Axial Tilt and Spin 04:15 Implementation Summary 05:49 Comparing Simulation Options 07:43 Burst Results 08:14 Rendering - Meshes 09:55 Culling and LODs 11:06 Deterministic Order in Jobs 12:00 Outro