Adding a bezier curve example

[Kjolnyr]

Objective

Examples on how to use the freshly merged Bezier struct ( #7653 ) are missing.

Solution

• Added a bezier_curve.rs example in the animation/ folder.

[aevyrie]

Do we have any guidance on what level of features should get examples? I have a bunch of example code for cubic curves, but wasn't sure if it would be valuable outside of a higher-level context, e.g. general animation or shape rendering.

[aevyrie]

Some small changes, but otherwise looks good. Would it be more precise to call this cubic_curve? The techniques shown here can be applied to any of Bevy's supplied cubic curves, not just Beziers.

[Kjolnyr]

Changed the example name to cubic_curve, I've also changed the relevant comments to talk about cubic_curve instead of bezier.

[aevyrie]

I think this is a nice addition as-is. I've included some nits, but wouldn't block on them.

[aevyrie]

I'd remove this comment to avoid duplicating the docs. I'd also prefer using t instead of step, as it is the standard input into a parametric function, and is what is used in the docs: https://docs.rs/bevy/latest/bevy/math/cubic_splines/struct.CubicCurve.html#method.position

As above, this is a pretty minor nit, and could be ignored.

[Kjolnyr]

Good point for t instead of step, however, I'd keep the comment even though it's duplicating the docs to avoid any confusion the user would have.

[alice-i-cecile]

I very much like keeping the duplicative comment here :) The information is important and relevant here.

[hymm]

Should the cube be coming off the curve on the right side?

[aevyrie]

@hymm pretty sure it's this bug: #8049

[hymm]

pretty sure it's this bug: #8049

I merged in main and it fixed it. Thanks for the info.

[alice-i-cecile]

Do we have any guidance on what level of features should get examples? I have a bunch of example code for cubic curves, but wasn't sure if it would be valuable outside of a higher-level context, e.g. general animation or shape rendering.

@aevyrie I would be happy to see these in bevy_math. If it has pedagogical value or can be used to quickly visually check correctness, it's worth including IMO. In this case, many users won't be familiar with the exact mechanisms of spline curves, which are extremely useful even outside of graphics and animation.

[alice-i-cecile]

Looks good: the debug line is particularly helpful! I'm going to push a fix up for CI; please re-review when you see it :)

[alice-i-cecile]

@Kjolnyr I couldn't get pushing to your branch to cooperate: can you remove the empty //! at the start of the example and run cargo fmt so CI will pass?

[Kjolnyr]

That's probably because I synced my fork with bevy's current main, sorry for that. I'll remove the empty //! and fix CI