Add a page explaining Roblox physics

Currently when you google “Roblox physics”, all you get is a blog post from 2015 and a few articles on specific parts of Roblox physics. There is no official page explaining what the physics engine is capable of

This page should include what all the different joints are, how they all work and demo files that developers could download to see how a specific joint works. It should also mention collision groups, network ownership, also maybe technical articles written by the physics engineers that made the system explaining how it works


Yeah, we really lack of lot of documentation. I’ve made various physics based projects and every time it was made through trial and error.

The closest thing I know of is this thread:


I’ve actually also searched for documentation on this a while ago and landed in the same boat. It would be helpful to know all of the components and how they work in order to help us develop physics related systems more easily.

I want for example make Lava, very similar to water, but with other textures and yes, but Roblox not really explain how it‘s water work (I think this should be physics). Then; many time ago, i received a help message that include Roblox physics (it was to include air resistence in the game), but as i not really know how to include it in (and it was to hard to calculate without missing informations from Roblox), i not helped this person (i tried, but to hard). I really want to know how to engine works, as @gillern say‘s. We need to search and we can‘t find anything. If we find something, then it was old and sure updated, so currently it was impossible to find the ting we want. So i say yeah, we need a better documentation.

In answering these questions with a DevHub article, a few good resources pop to mind.

I’d recommend checking out this talk @ContextLost did during RDC 2019. It’s still missing the PowerPoint unfortunately, but it’s absolutely worth a listen. It answers a lot of the questions asked in this topic.

There was also a GDC talk done recently by @chefdeletat which digs into the math that drives the LDL-PGS constraint solver. It’s very technical and implies you have a strong background in the concepts it dives into.

Roblox’s physics engine is really interesting behind the scenes, from what I remember of it. There are so many hidden layers and components to it which aren’t user facing.

I spent time documenting the Physics settings when I was on the IX team 2 years ago. The systems have changed since then since they phased out the old physics solver, but they were accurate up to that point.


We will be working to get better documentation out there over time.

I think there is a pretty good intro to the engine found here:
Just click “Physics” and check out those 6 pages. I think the problem is that this “section” of pages is not very easy to find. You can also find a page for each physics constraint on the devhub.

The videos and my other forum post are also good to check out. I hope to get the info from my old foum post better dispersed around the devhub.

If you feel that after looking over that info you are still lacking on some information, feel free to ask here and I’ll try to answer, and note it as something to get better documentation on.


They’re probably not going to update the video, but here’s the slides!