add an example featuring full lines instantly through debug_lines dependency

[ThierryBerger]

I figured I would adress vleue/polyanya#2 here rather than in polyanya ; I kept the code very similar to the polyanya example.

I really dislike:

• the coordinates translations from screen to navmesh, we should simplify that more ergonomically.
• the match to the mesh handle, I think all info should be in a resource to avoid multiple arguments to the functions (add Handle to MeshDetails ? it requires quite a refactoring because it cannot be const)
• the UI being rebuilt fully, well it's not the point of the example and it's only on spacebar so it's minor, but reloading the font and recreating materials is not a good practice 🤐.

[mockersf]

Thanks! I agree with your points, and intend to fix them!

• the coordinates translations from screen to navmesh, we should simplify that more ergonomically.

Yup. I work by adding stuff to the example, then moving what need to be common to the plugin. I want to move that part to the plugin so that it works in navmesh coordinates, and have a one place to do the translation between the two coordinate systems

• the match to the mesh handle, I think all info should be in a resource to avoid multiple arguments to the functions (add Handle to MeshDetails ? it requires quite a refactoring because it cannot be const)

It's possible to have const handle with HandleUntyped, it's what Bevy is doing for its internal assets.

• the UI being rebuilt fully, well it's not the point of the example and it's only on spacebar so it's minor, but reloading the font and recreating materials is not a good practice 🤐.

I agree it's not nice, but not the point of the example 🤷