bevy/crates/bevy_math
Joona Aalto cf15e6bba3
Implement Meshable for some 3D primitives (#11688)
# Objective

Split up from #11007, fixing most of the remaining work for #10569.

Implement `Meshable` for `Cuboid`, `Sphere`, `Cylinder`, `Capsule`,
`Torus`, and `Plane3d`. This covers all shapes that Bevy has mesh
structs for in `bevy_render::mesh::shapes`.

`Cone` and `ConicalFrustum` are new shapes, so I can add them in a
follow-up, or I could just add them here directly if that's preferrable.

## Solution

Implement `Meshable` for `Cuboid`, `Sphere`, `Cylinder`, `Capsule`,
`Torus`, and `Plane3d`.

The logic is mostly just a copy of the the existing `bevy_render`
shapes, but `Plane3d` has a configurable surface normal that affects the
orientation. Some property names have also been changed to be more
consistent.

The default values differ from the old shapes to make them a bit more
logical:

- Spheres now have a radius of 0.5 instead of 1.0. The default capsule
is equivalent to the default cylinder with the sphere's halves glued on.
- The inner and outer radius of the torus are now 0.5 and 1.0 instead of
0.5 and 1.5 (i.e. the new minor and major radii are 0.25 and 0.75). It's
double the width of the default cuboid, half of its height, and the
default sphere matches the size of the hole.
- `Cuboid` is 1x1x1 by default unlike the dreaded `Box` which is 2x1x1.

Before, with "old" shapes:


![old](https://github.com/bevyengine/bevy/assets/57632562/733f3dda-258c-4491-8152-9829e056a1a3)

Now, with primitive meshing:


![new](https://github.com/bevyengine/bevy/assets/57632562/5a1af14f-bb98-401d-82cf-de8072fea4ec)

I only changed the `3d_shapes` example to use primitives for now. I can
change them all in this PR or a follow-up though, whichever way is
preferrable.

### Sphere API

Spheres have had separate `Icosphere` and `UVSphere` structs, but with
primitives we only have one `Sphere`.

We need to handle this with builders:

```rust
// Existing structs
let ico = Mesh::try_from(Icophere::default()).unwrap();
let uv = Mesh::from(UVSphere::default());

// Primitives
let ico = Sphere::default().mesh().ico(5).unwrap();
let uv = Sphere::default().mesh().uv(32, 18);
```

We could add methods on `Sphere` directly to skip calling `.mesh()`.

I also added a `SphereKind` enum that can be used with the `kind`
method:

```rust
let ico = Sphere::default()
    .mesh()
    .kind(SphereKind::Ico { subdivisions: 8 })
    .build();
```

The default mesh for a `Sphere` is an icosphere with 5 subdivisions
(like the default `Icosphere`).

---

## Changelog

- Implement `Meshable` and `Default` for `Cuboid`, `Sphere`, `Cylinder`,
`Capsule`, `Torus`, and `Plane3d`
- Use primitives in `3d_shapes` example

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
2024-02-06 21:44:13 +00:00
..
src Implement Meshable for some 3D primitives (#11688) 2024-02-06 21:44:13 +00:00
Cargo.toml Implement approx traits for direction types (#11650) 2024-02-01 19:22:28 +00:00