Jondolf

Previously, Avian has supported f64 with a feature flag that changes almost everything to double-precision. This changes with my f64 overhaul. In short: Use f64 only for world-space values that degrade in precision far from the origin. This approach is inspired by Jolt. github.com/avianphysics...

Here is a scene at 1e7 meters from the origin along the x-axis using single-precision. You can see the bodies form rows and get stuck in these quantized x-coordinates, as the floating-point step is about one meter at these distances. Behavior is very wonky!

Previously, Avian has supported f64 with a feature flag that changes almost everything to double-precision. This changes with my f64 overhaul. In short: Use f64 only for world-space values that degrade in precision far from the origin. This approach is inspired by Jolt. github.com/avianphysics...

Why, you may ask? 1. Our Scalar and Vector type alias spam in examples has been paining me since the start. People should learn to just use f32, Vec2, Vec3, Quat, etc. 2. Contributors regularly get CI errors due to f32/f64 type mismatches, causing a lot of gray hairs 3. Using f64 so widely is costly

i have received word from a carrier pigeon that you should do today's wordle

An overhauled Box2D-inspired Continuous Collision Detection algorithm has landed in Avian! It uses a form of swept CCD by default for fast-moving bodies. #physics #gamedev #avian #bevy github.com/avianphysics...

You can also see how sweep-based CCD can reliably handle fast rotational movement (depending on the sweep mode), but has the downside of "time loss". However, enabling additional speculative CCD helps alleviate it.

An overhauled Box2D-inspired Continuous Collision Detection algorithm has landed in Avian! It uses a form of swept CCD by default for fast-moving bodies. #physics #gamedev #avian #bevy github.com/avianphysics...

The major improvement over our previous Bepu-style speculative CCD is that you no longer get ghost collisions when moving past objects at a high speed, as the default speculative distance is kept at a very small, fixed value.

Avian's broad phase collision detection has finally been overhauled to use Bounding Volume Hierarchies from the OBVHS crate! Previously, basic sweep and prune was used. This is a stress test with colliders in a grid moving randomly, rendering the resulting BVH. #bevy PR: github.com/avianphysics...

Huge thanks to DGriffin91 for implementing incremental leaf insertion and removal, partial rebuilds, improved traversal, and much more for OBVHS to make it suitable for physics <3 Go show him and OBVHS some love! github.com/DGriffin91/o...

Avian's broad phase collision detection has finally been overhauled to use Bounding Volume Hierarchies from the OBVHS crate! Previously, basic sweep and prune was used. This is a stress test with colliders in a grid moving randomly, rendering the resulting BVH. #bevy PR: github.com/avianphysics...

The performance impact is massive for scenes with a large number of colliders. Previously, 40k static colliders in 2D could easily cost nearly 10 ms of the frame budget, while it is now under 1 ms. Dynamic scenes also perform a lot better than before.

Initial support for joint motors has finally landed on Avian's main branch! #bevy #physics #simulation github.com/avianphysics/avian/pull/913

Note that the implementation may end up being rewritten if/when we finally switch our XPBD joint solver to something else. But joint motors have been a common request, and the API will likely remain the same even if we change the internals, so I decided that it's worth shipping them already :)

Initial support for joint motors has finally landed on Avian's main branch! #bevy #physics #simulation github.com/avianphysics/avian/pull/913

I just released version 0.5 of Avian, an ECS-driven physics engine for @bevy.org. This is the first update under our new release process, where we publish Bevy version updates separately from feature releases. As always, an announcement post can be found here: joonaa.dev/blog/11/avia...

Avian finally has built-in move and slide, the movement and collision algorithm at the heart of kinematic character controllers! #bevy #gamedev #physics #kcc PR: github.com/avianphysics...

Note that this currently just includes a MoveAndSlide system parameter and related utilities. More user-friendly ECS-driven APIs, character controller features, and examples will come later.

Avian finally has built-in move and slide, the movement and collision algorithm at the heart of kinematic character controllers! #bevy #gamedev #physics #kcc PR: github.com/avianphysics...

Avian is getting pretty big nowadays! To mark the start of a new release cycle, I spent some time improving our processes moving forward. Notably, Avian now stores migration guides in-repo, similar to Bevy: github.com/avianphysics...

After seeing the old Avian URL for so long, it does look a bit weird now 😅 But I think it's good long-term, just a matter of getting used to it :)

Avian is getting pretty big nowadays! To mark the start of a new release cycle, I spent some time improving our processes moving forward. Notably, Avian now stores migration guides in-repo, similar to Bevy: github.com/avianphysics...

This has several major benefits: main branch users have migration guides available, the guides are kept up-to-date (and written by the people who made the changes), and I don't have to crunch at the end of each cycle to gather them from scattered PRs and spend ages fixing and updating them.

Today, I finally merged simulation islands for Avian! Islands are graph-like structures where bodies are connected via contacts or joints. They are used for sleeping and waking, which is crucial for reducing CPU overhead for large scenes with many dynamic bodies. github.com/Jondolf/avia...

Avian's implementation persists islands across time steps, minimizing island building and splitting overhead. It is primarily based on @erincatto.bsky.social's excellent Simulation Islands article and Box2D. box2d.org/posts/2023/1...

Today, I finally merged simulation islands for Avian! Islands are graph-like structures where bodies are connected via contacts or joints. They are used for sleeping and waking, which is crucial for reducing CPU overhead for large scenes with many dynamic bodies. github.com/Jondolf/avia...