# Objective
The objective is to be able to load data from "application-specific"
(see glTF spec 3.7.2.1.) vertex attribute semantics from glTF files into
Bevy meshes.
## Solution
Rather than probe the glTF for the specific attributes supported by
Bevy, this PR changes the loader to iterate through all the attributes
and map them onto `MeshVertexAttribute`s. This mapping includes all the
previously supported attributes, plus it is now possible to add mappings
using the `add_custom_vertex_attribute()` method on `GltfPlugin`.
## Changelog
- Add support for loading custom vertex attributes from glTF files.
- Add the `custom_gltf_vertex_attribute.rs` example to illustrate
loading custom vertex attributes.
## Migration Guide
- If you were instantiating `GltfPlugin` using the unit-like struct
syntax, you must instead use `GltfPlugin::default()` as the type is no
longer unit-like.
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