Treat BVH animation data as an asset and create an asset loader for it

[nixon-voxell]

The Idea

At the moment, BVH data is loaded and stored inside a Bevy resource struct as a list:

#[derive(Resource)]
pub struct BvhData {
    pub bvh_animation: Vec<Bvh>,
}

This approach left developers unable to reference a unique Bvh animation without risking the chances of it being removed or moved as the only approach right now is to store the index of that Bvh animation.

Example

During runtime, an index might be used to reference a specific Bvh animation in the bvh_animation list:

let index = None;
for i in 0..bvh_animation.len() {
    // find specific bvh animation
    if xxx == yyy {
        index = Some(i);
        break;
    }
}

The specific index that is being extracted might not stay true if something like this happen during runtime:

bvh_animation.insert(0, new_bvh);

This is a hypothetical situation that may or may not happen for whatever reason, but knowing that such a simple innocent insert operation might cause a seemingly untraceable bug is mind-boggling!

Proposed Solution

We treat every Bvh animation as an asset (a simplified sample). Instead of storing indices pointing to a specific animation, we use Bevy's asset Handle<T> system.

This will guarantee us a unique pointer towards the Bvh animation asset and tell us when it is missing.

Bevy Handle<T> doc: https://docs.rs/bevy/latest/bevy/prelude/enum.Handle.html
Bevy Assets doc:

• https://docs.rs/bevy/latest/bevy/asset/struct.Assets.html
• https://docs.rs/bevy/latest/bevy/asset/index.html

[ConquerorFY]

Can check out branch and see @nixon-voxell