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Life & fun · January 1, 2023

Detecting collision between 500k circles below 5ms

Heya. I created a flexible collision engine for broad detection in C that's also pretty fast. Personally that's my best, so I wanted to show it here. Although... still not as fast as DragonEnergy's one that supposedly handled millions of agents bouncing off each other every frame on an old i3, haha. I hope I get better at this! He set the bar pretty high for me. I was considering including some small function that tries finding the nearest entity, although I think it might be better to simply use query for that matter. Perhaps in the future I will get a good idea of how to do that more…

Detecting collision between 500k circles below 5ms launched on January 1, 2023 with 59 votes, #1,149 of 3,901 launches that month and more than 90% of that year's launches. The site was still online in September 2026, 3 years on.

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In plain words

This is a collision detection engine written in C that handles broad-phase collision checks for circles. It performs collision detection on 500,000 circles in under 5 milliseconds on standard hardware. The tool is designed for developers building physics simulations or games that need fast collision checking. The engine calculates distances between objects and applies forces based on angles between them rather than using simplified square-based approximations.

written from the facts on this page · September 2026

From the sources

1D/2D/3D Hierarchical Spatial Hash Grid written in C - supahero1/hshg

In the maker’s words, at launch

Heya. I created a flexible collision engine for broad detection in C that's also pretty fast. Personally that's my best, so I wanted to show it here. Although... still not as fast as DragonEnergy's one that supposedly handled millions of agents bouncing off each other every frame on an old i3, haha. I hope I get…

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