glTFs are rotated 180 degrees due to lack of coordinate space conversion.

[Noxmore]

Bevy version

0.16.0

What you did

I'm working on my integration for the Trenchbroom level editor, and I've noticed that Bevy shows glTFs rotated 180 degrees compared to Trenchbroom.

What went wrong

Looking at the screenshot below, "fwd" points to the blue axis: +Z (provided by Gizmos::axes()), rather than -Z, and the same situation with "right".

This is wrong because glTF has a +Z forward coordinate space, so it should be rotated to conform to Bevy's forward.

Additional information

Model used

[janhohenheim]

Looks like a bug to me, but I'd like some rendering people to confirm.
If this is indeed wrong, we should fix this ASAP to reduce the amount of annoyed users having to flip their glTFs in their levels. Putting it in the 0.17 milestone for that reason.

Edit: minimal reproduction

use bevy::prelude::*;

fn main() -> AppExit {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_systems(Startup, setup)
        .add_systems(Update, transform_gizmos)
        .run()
}

fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
    commands.spawn((
        Camera3d::default(),
        Transform::from_xyz(-2.0, 2.0, 3.0).looking_at(Vec3::ZERO, Vec3::Y),
    ));
    commands.spawn(SceneRoot(asset_server.load("gizmo.glb#Scene0")));
}

fn transform_gizmos(mut gizmos: Gizmos, query: Query<&GlobalTransform, Without<Camera>>) {
    for global_transform in &query {
        gizmos.axes(*global_transform, 1.);
    }
}

[janhohenheim]

Closing as duplicate of #5670