Vello 0.2.1

Vello v0.2.1 is here!

This release is a patch to resolve #291, which is a crash when attempting to render an empty scene. We now also require wgpu v0.20.1, as wgpu 0.20.0 was yanked.

Read the changelog for full details.

This release also coincides with the release of v0.2.1 of Vello Shaders and Vello Encoding.