Velato

An integration to parse and render Lottie with Vello.

Warning

The goal of this crate is to provide coverage of the large Lottie spec, up to what vello can render, for use in interactive graphics. We are working towards correctness, but there are missing features listed below.

Missing features

Several Lottie features are not yet supported, including:

• Position keyframe (ti, to) easing
• Time remapping (tm)
• Text
• Image embedding
• Advanced shapes (stroke dash, zig-zag, etc.)
• Advanced effects (motion blur, drop shadows, etc.)
• Correct color stop handling
• Split rotations
• Split positions

Usage

Velato makes it simple to encode Lottie as a vello::Scene.

// Parse your lottie file
let lottie = include_str!("../lottie.json");
let composition = velato::Composition::from_str(lottie).expect("valid file");

// Render to a scene
let mut new_scene = vello::Scene::new();

// Render to a scene!
let mut renderer = velato::Renderer::new();
let frame = 0.0; // Arbitrary number chosen. Ensure it's a valid frame!
let transform = vello::kurbo::Affine::IDENTITY;
let alpha = 1.0;
renderer.render(&composition, frame, transform, alpha, &mut new_scene);

Examples

Cross platform (Winit)

cargo run -p with_winit

You can also load an entire folder or individual files.

cargo run -p with_winit -- examples/assets

Web platform

Because Vello relies heavily on compute shaders, we rely on the emerging WebGPU standard to run on the web. Until browser support becomes widespread, it will probably be necessary to use development browser versions (e.g. Chrome Canary) and explicitly enable WebGPU.

This uses cargo-run-wasm to build the example for web, and host a local server for it

# Make sure the Rust toolchain supports the wasm32 target
rustup target add wasm32-unknown-unknown

# The binary name must also be explicitly provided as it differs from the package name
cargo run_wasm -p with_winit --bin with_winit_bin

There is also a web demo available here on supporting web browsers.

Warning

The web is not currently a primary target for Vello, and WebGPU implementations are incomplete, so you might run into issues running this example.

Minimum supported Rust Version (MSRV)

This version of Velato has been verified to compile with Rust 1.75 and later.

Future versions of Velato might increase the Rust version requirement. It will not be treated as a breaking change and as such can even happen with small patch releases.

Click here if compiling fails.

As time has passed, some of Velato's dependencies could have released versions with a higher Rust requirement. If you encounter a compilation issue due to a dependency and don't want to upgrade your Rust toolchain, then you could downgrade the dependency.

# Use the problematic dependency's name and version
cargo update -p package_name --precise 0.1.1

Community

Discussion of Velato development happens in the Linebender Zulip, specifically the #gpu stream. All public content can be read without logging in.

Contributions are welcome by pull request. The Rust code of conduct applies.

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

The files in subdirectories of the examples/assets directory are licensed solely under their respective licenses, available in the LICENSE file in their directories.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.