Is there an idiomatic way to get a specific StandardMaterial from a given gltf/glb file by name? What about index?

[hannesojala]

I see there is a vec materials and a map named_materials on Gltf, but there does not seem to be a way to convert the resulting GltfMaterial into a StandardMaterial.

I see it is possible to get a material (by what I assume is the index) by doing:

    let material = asset_server.load::<StandardMaterial>("file.glb#Material0/std");

I can't find a way to map that material to a name except by manually inspecting the inner gltf::Gltf (from the gltf crate).

I might just be missing something obvious!

[hannesojala]

Would something like the following work in general?

Does calling asset_server.load reuse the work done to load the entire document?

  let Some(inner_gltf) = &gltf.source else {
        return;
  };

  let mut materials_by_name = HashMap::new();
  for material in inner_gltf.materials() {
      let Some(index) = material.index() else {
          continue; // is the DefaultMaterial
      };
      let Some(name) = material.name() else {
          continue; // only looking at named materials
      };
      let asset_path = format!("{asset_path}#Material{index}/std"); // Seems to be "Material{index}/std" as the label regardless of the material name
      let std_material = asset_server.load::<StandardMaterial>(asset_path);
      materials_by_name.insert(name, std_material);
  }

[lab1207]

You don't need the raw gltf crate: Gltf::materials is in glTF source order, so the position of a named_materials handle in that vec is the {index} you already use:

let gltf = gltf_assets.get(&gltf_handle).unwrap();
let mat = gltf.named_materials.get("MyMaterial").unwrap();
let index = gltf.materials.iter().position(|h| h == mat).unwrap();
let std_mat = asset_server.load::<StandardMaterial>(format!("{path}#Material{index}/std"));

The /std suffix is a real labeled asset: bevy_pbr's glTF extension handler registers a StandardMaterial at "{material_label}/std" for every material while loading (GltfExtensionHandlerPbr::on_material, crates/bevy_pbr/src/gltf.rs; the default material gets DefaultMaterial/std). Spawned primitives get MeshMaterial3d with that handle, so Material{index}/std is the StandardMaterial actually used by the scene — the one to mutate if you want to restyle it.

On 0.20 there is also bevy_pbr::gltf::standard_material_from_gltf_material(&GltfMaterial) -> StandardMaterial if you prefer converting the value yourself and adding your own asset.

@hannesojala: yes — asset_server.load("#Material0/std") reuses the single load. It just resolves the labeled asset created when the glTF was parsed; nothing is re-parsed. The gltf.source route in your snippet does require GltfLoaderSettings { include_source: true, .. }, which is off by default.

[hannesojala]

Gltf::materials is in glTF source order

Thanks! This is what I needed confirmed.