Example for axes gizmos

[mweatherley]

Objective

• Follow-up to Add coordinate axes gizmo #12211
• Introduces an example project that demonstrates the implementation and behavior of Gizmos::axes for an entity with a Transform component.

Solution

In order to demonstrate how Gizmo::axes can be used and behaves in practice, we introduce an example of a simple scene containing a pair of cuboids locked in a grotesque, inscrutable dance: the two are repeatedly given random Transforms which they interpolate to, showing how the axes move with objects as they translate, rotate, and scale.

On the implementation side, we demonstrate how to draw axes for entities, automatically sizing them according to their bounding boxes (so that the axes will be visible):

fn draw_axes(mut gizmos: Gizmos, query: Query<(&Transform, &Aabb), With<ShowAxes>>) {
    for (&transform, &aabb) in &query {
        let length = aabb.half_extents.length();
        gizmos.axes(transform, length);
    }
}

---

Changelog

• Created examples/gizmos/axes.rs.
• Added 'axes' example to Cargo.toml.

[alice-i-cecile]

It might be nicer to show how to create automatically scaled axes in this example, rather than customizing the length, but I don't feel strongly.

[pablo-lua]

How about adding another box with other set of axes? Then we could have both

[mweatherley]

It might be nicer to show how to create automatically scaled axes in this example, rather than customizing the length, but I don't feel strongly.

Good idea! I'll size the axes based on the Aabb component like I mentioned in the first PR.

[mweatherley]

How about adding another box with other set of axes? Then we could have both

I tried this out, but I felt that playing with the axis sizing detracted from the demonstration of the tool's main utility (drawing axes on objects for debugging) so I tried to do a good job of just demonstrating automatically sized axes instead.

[pablo-lua]

Good example, showing the user that they can go very far with this feature!