Commit graph

150 commits

Author SHA1 Message Date
Joona Aalto
4bed1b2200
Add note about rotations for Aabb3d (#12315)
# Objective

Fixes #12310.

#11681 added transformations for bounding volumes, but I accidentally
only added a note in the docs about repeated rotations for `Aabb2d` and
not `Aabb3d`.

## Solution

Copy the docs over to `Aabb3d`.
2024-03-05 17:22:53 +00:00
Joona Aalto
921ba54acf
Support transforming bounding volumes (#11681)
# Objective

Make it straightforward to translate and rotate bounding volumes.

## Solution

Add `translate_by`/`translated_by`, `rotate_by`/`rotated_by`,
`transform_by`/`transformed_by` methods to the `BoundingVolume` trait.
This follows the naming used for mesh transformations (see #11454 and
#11675).

---

## Changelog

- Added `translate_by`/`translated_by`, `rotate_by`/`rotated_by`,
`transform_by`/`transformed_by` methods to the `BoundingVolume` trait
and implemented them for the bounding volumes
- Renamed `Position` associated type to `Translation`

---------

Co-authored-by: Mateusz Wachowiak <mateusz_wachowiak@outlook.com>
2024-03-05 00:48:45 +00:00
Joona Aalto
983da7677a
Improve error messages for denormalized directions (#12278)
# Objective

`Dir3` and `Dir3A` can be rotated using `Quat`s. However, if enough
floating point error accumulates or (more commonly) the rotation itself
is degenerate (like not normalized), the resulting direction can also
become denormalized.

Currently, with debug assertions enabled, it panics in these cases with
the message `rotated.is_normalized()`. This error message is unclear,
doesn't give information about *how* it is denormalized (like is the
length too large, NaN, or something else), and is overall not very
helpful. Panicking for small-ish error might also be a bit too strict,
and has lead to unwanted crashes in crates like `bevy_xpbd` (although it
has also helped in finding actual bugs).

The error message should be clearer and give more context, and it
shouldn't cause unwanted crashes.

## Solution

Change the `debug_assert!` to a warning for small error with a (squared
length) threshold of 2e-4 and a panic for clear error with a threshold
of 2e-2. The warnings mention the direction type and the length of the
denormalized vector.

Here's what the error and warning look like:

```
Error: `Dir3` is denormalized after rotation. The length is 1.014242.
```

```
Warning: `Dir3A` is denormalized after rotation. The length is 1.0001414.
```

I gave the same treatment to `new_unchecked`:

```
Error: The vector given to `Dir3::new_unchecked` is not normalized. The length is 1.014242.
```

```
Warning: The vector given to `Dir3A::new_unchecked` is not normalized. The length is 1.0001414.
```

---

## Discussion

### Threshold values

The thresholds are somewhat arbitrary. 2e-4 is what Glam uses for the
squared length in `is_normalized` (after I corrected it in
bitshifter/glam-rs#480), and 2e-2 is just what I thought could be a
clear sign of something being critically wrong. I can definitely tune
them if there are better thresholds though.

### Logging

`bevy_math` doesn't have `bevy_log`, so we can't use `warn!` or
`error!`. This is why I made it use just `eprintln!` and `panic!` for
now. Let me know if there's a better way of logging errors in
`bevy_math`.
2024-03-04 00:01:32 +00:00
Joona Aalto
6032978eba
Implement Mul between f32 and direction types (#12276)
# Objective

Bevy's `Dir3` and `Dir3A` only implement `Mul<f32>` and not vice versa,
and `Dir2` can not be multiplied by `f32` at all. They all should
implement multiplication both ways, just like Glam's vector types.

## Solution

Implement `Mul<Dir2>`, `Mul<Dir3>`, and `Mul<Dir3A>` for `f32`, and
`Mul<f32>` for `Dir2`.
2024-03-03 17:44:16 +00:00
Joona Aalto
f418de8eb6
Rename Direction2d/3d to Dir2/3 (#12189)
# Objective

Split up from #12017, rename Bevy's direction types.

Currently, Bevy has the `Direction2d`, `Direction3d`, and `Direction3dA`
types, which provide a type-level guarantee that their contained vectors
remain normalized. They can be very useful for a lot of APIs for safety,
explicitness, and in some cases performance, as they can sometimes avoid
unnecessary normalizations.

However, many consider them to be inconvenient to use, and opt for
standard vector types like `Vec3` because of this. One reason is that
the direction type names are a bit long and can be annoying to write (of
course you can use autocomplete, but just typing `Vec3` is still nicer),
and in some intances, the extra characters can make formatting worse.
The naming is also inconsistent with Glam's shorter type names, and
results in names like `Direction3dA`, which (in my opinion) are
difficult to read and even a bit ugly.

This PR proposes renaming the types to `Dir2`, `Dir3`, and `Dir3A`.
These names are nice and easy to write, consistent with Glam, and work
well for variants like the SIMD aligned `Dir3A`. As a bonus, it can also
result in nicer formatting in a lot of cases, which can be seen from the
diff of this PR.

Some examples of what it looks like: (copied from #12017)

```rust
// Before
let ray_cast = RayCast2d::new(Vec2::ZERO, Direction2d::X, 5.0);

// After
let ray_cast = RayCast2d::new(Vec2::ZERO, Dir2::X, 5.0);
```

```rust
// Before (an example using Bevy XPBD)
let hit = spatial_query.cast_ray(
    Vec3::ZERO,
    Direction3d::X,
    f32::MAX,
    true,
    SpatialQueryFilter::default(),
);

// After
let hit = spatial_query.cast_ray(
    Vec3::ZERO,
    Dir3::X,
    f32::MAX,
    true,
    SpatialQueryFilter::default(),
);
```

```rust
// Before
self.circle(
    Vec3::new(0.0, -2.0, 0.0),
    Direction3d::Y,
    5.0,
    Color::TURQUOISE,
);

// After (formatting is collapsed in this case)
self.circle(Vec3::new(0.0, -2.0, 0.0), Dir3::Y, 5.0, Color::TURQUOISE);
```

## Solution

Rename `Direction2d`, `Direction3d`, and `Direction3dA` to `Dir2`,
`Dir3`, and `Dir3A`.

---

## Migration Guide

The `Direction2d` and `Direction3d` types have been renamed to `Dir2`
and `Dir3`.

## Additional Context

This has been brought up on the Discord a few times, and we had a small
[poll](https://discord.com/channels/691052431525675048/1203087353850364004/1212465038711984158)
on this. `Dir2`/`Dir3`/`Dir3A` was quite unanimously chosen as the best
option, but of course it was a very small poll and inconclusive, so
other opinions are certainly welcome too.

---------

Co-authored-by: IceSentry <c.giguere42@gmail.com>
2024-02-28 22:48:43 +00:00
JohnTheCoolingFan
a543536a34
Cubic splines overhaul (#10701)
# Objective

Improve the `bevy::math::cubic_splines` module by making it more
flexible and adding new curve types.
Closes #10220 

## Solution

Added new spline types and improved existing

---

## Changelog

### Added

- `CubicNurbs` rational cubic curve generator, allows setting the knot
vector and weights associated with every point
- `LinearSpline` curve generator, allows generating a linearly
interpolated curve segment
- Ability to push additional cubic segments to `CubicCurve`
- `IntoIterator` and `Extend` implementations for `CubicCurve`

### Changed

- `Point` trait has been implemented for more types: `Quat` and `Vec4`.
- `CubicCurve::coefficients` was moved to `CubicSegment::coefficients`
because the function returns `CubicSegment`, so it seems logical to be
associated with `CubicSegment` instead. The method is still not public.

### Fixed

- `CubicBSpline::new` was referencing Cardinal spline instead of
B-Spline

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: IQuick 143 <IQuick143cz@gmail.com>
Co-authored-by: Miles Silberling-Cook <nth.tensor@gmail.com>
Co-authored-by: Joona Aalto <jondolf.dev@gmail.com>
2024-02-28 17:18:42 +00:00
Joona Aalto
9bd6cc0a5e
Add Direction3dA and move direction types out of primitives (#12018)
# Objective

Split up from #12017, add an aligned version of `Direction3d` for SIMD,
and move direction types out of `primitives`.

## Solution

Add `Direction3dA` and move direction types into a new `direction`
module.

---

## Migration Guide

The `Direction2d`, `Direction3d`, and `InvalidDirectionError` types have
been moved out of `bevy::math::primitives`.

Before:

```rust
use bevy::math::primitives::Direction3d;
```

After:

```rust
use bevy::math::Direction3d;
```

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
2024-02-26 13:57:49 +00:00
github-actions[bot]
e7c3359c4b
Bump Version after Release (#12020)
Fixes #12016.

Bump version after release
This PR has been auto-generated

Co-authored-by: Bevy Auto Releaser <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: François <mockersf@gmail.com>
2024-02-21 20:58:59 +00:00
Aztro
eef7dbefe8
Add single-f32 constructors for a few (very few) primitives (#11934)
# Objective

- I hated having to do `Cuboid::new(1.0, 1.0, 1.0)` or
`Cuboid::from_size(Vec3::splat(1.0))` when there should be a much easier
way to do this.

## Solution

- Implemented a `from_length()` method that only takes in a single
float, and constructs a primitive of equal size in all directions.
- Ex:
  ```rs
  // These:
  Cuboid::new(1.0, 1.0, 1.0);
  Cuboid::from_size(Vec3::splat(1.0));
  // Are equivalent to this:
  Cuboid::from_length(1.0);
  ```
 - For the rest of the changed primitives:
    ```rs
    Rectangle::from_length(1.0);
    Plane3d::default().mesh().from_length(1.0);
    ```
2024-02-18 07:43:45 +00:00
Carter Anderson
abb8c353f4
Release 0.13.0 (#11920)
Bump Bevy crates to 0.13.0 in preparation for release.

(Note that we accidentally skipped the `0.13.0-dev` step this cycle)
2024-02-17 09:24:25 +00:00
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
Tristan Guichaoua
694c06f3d0
Inverse missing_docs logic (#11676)
# Objective

Currently the `missing_docs` lint is allowed-by-default and enabled at
crate level when their documentations is complete (see #3492).
This PR proposes to inverse this logic by making `missing_docs`
warn-by-default and mark crates with imcomplete docs allowed.

## Solution

Makes `missing_docs` warn at workspace level and allowed at crate level
when the docs is imcomplete.
2024-02-03 21:40:55 +00:00
Joona Aalto
9bad607df9
Implement meshing for Capsule2d (#11639)
# Objective

The `Capsule2d` primitive was added in #11585. It should support meshing
like the other 2D primitives.

## Solution

Implement meshing for `Capsule2d`.

It doesn't currently support "rings" like Bevy's `Capsule` shape (not
`Capsule3d`), but it does support resolution to control the number of
vertices used for one hemicircle. The total vertex count is two times
the resolution; if we allowed setting the full vertex count, odd numbers
would lead to uneven vertex counts for the top and bottom hemicircles
and produce potentially unwanted results.

The capsule looks like this (with UV visualization and wireframe) using
resolutions of 16, 8, and 3:

![Resolution
16](https://github.com/bevyengine/bevy/assets/57632562/feae22de-bdc5-438a-861f-848284b67a52)
![Resolution
8](https://github.com/bevyengine/bevy/assets/57632562/e95aab8e-793f-45ac-8a74-8be39f7626dd)
![Resolution of
3](https://github.com/bevyengine/bevy/assets/57632562/bcf01d23-1d8b-4cdb-966a-c9022a07c287)

The `2d_shapes` example now includes the capsule, so we also get one
more color of the rainbow 🌈

![New 2D shapes
example](https://github.com/bevyengine/bevy/assets/57632562/1c45b5f5-d26a-4e8c-8e8a-e106ab14d46e)
2024-02-03 18:03:43 +00:00
Robert Walter
041731b7e0
Drawing Primitives with Gizmos (#11072)
The PR is in a reviewable state now in the sense that the basic
implementations are there. There are still some ToDos that I'm aware of:

- [x] docs for all the new structs and traits
- [x] implement `Default` and derive other useful traits for the new
structs
- [x] Take a look at the notes again (Do this after a first round of
reviews)
- [x] Take care of the repetition in the circle drawing functions

---

# Objective

- TLDR: This PR enables us to quickly draw all the newly added
primitives from `bevy_math` in immediate mode with gizmos
- Addresses #10571

## Solution

- This implements the first design idea I had that covered everything
that was mentioned in the Issue
https://github.com/bevyengine/bevy/issues/10571#issuecomment-1863646197

--- 

## Caveats

- I added the `Primitive(2/3)d` impls for `Direction(2/3)d` to make them
work with the current solution. We could impose less strict requirements
for the gizmoable objects and remove the impls afterwards if the
community doesn't like the current approach.

---

## Changelog

- implement capabilities to draw ellipses on the gizmo in general (this
was required to have some code which is able to draw the ellipse
primitive)
- refactored circle drawing code to use the more general ellipse drawing
code to keep code duplication low
- implement `Primitive2d` for `Direction2d` and impl `Primitive3d` for
`Direction3d`
- implement trait to draw primitives with specialized details with
gizmos
  - `GizmoPrimitive2d` for all the 2D primitives
  - `GizmoPrimitive3d` for all the 3D primitives
- (question while writing this: Does it actually matter if we split this
in 2D and 3D? I guess it could be useful in the future if we do
something based on the main rendering mode even though atm it's kinda
useless)

---

---------

Co-authored-by: nothendev <borodinov.ilya@gmail.com>
2024-02-02 21:13:03 +00:00
Rose Hudson
d6f1649646
return Direction3d from Transform::up and friends (#11604)
# Objective
Drawing a `Gizmos::circle` whose normal is derived from a Transform's
local axes now requires converting a Vec3 to a Direction3d and
unwrapping the result, and I think we shold move the conversion into
Bevy.

## Solution
We can make
`Transform::{left,right,up,down,forward,back,local_x,local_y,local_z}`
return a Direction3d, because they know that their results will be of
finite non-zero length (roughly 1.0).

---

## Changelog
`Transform::up()` and similar functions now return `Direction3d` instead
of `Vec3`.

## Migration Guide
Callers of `Transform::up()` and similar functions may have to
dereference the returned `Direction3d` to get to the inner `Vec3`.

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Joona Aalto <jondolf.dev@gmail.com>
2024-02-02 15:05:35 +00:00
NiseVoid
0ffc8d8a6f
Rename RayTest to RayCast (#11635)
# Objective

- `RayTest` vs `AabbCast` and `CircleCast` is inconsistent

## Solution

- Renaming the other two would only make the name more confusing, so we
rename `RayTest2d/3d` to `RayCast2d/3d`
2024-02-02 15:01:04 +00:00
Joona Aalto
6f2eec8f78
Support rotating Direction3d by Quat (#11649)
# Objective

It's often necessary to rotate directions, but it currently has to be
done like this:

```rust
Direction3d::new_unchecked(quat * *direction)
```

It'd be nice if you could rotate `Direction3d` directly:

```rust
quat * direction
```

## Solution

Implement `Mul<Direction3d>` for `Quat` ~~and the other way around.~~
(Glam doesn't impl `Mul<Quat>` or `MulAssign<Quat>` for `Vec3`)

The quaternion must be a unit quaternion to keep the direction
normalized, so there is a `debug_assert!` to be sure. Almost all `Quat`
constructors produce unit quaternions, so there should only be issues if
doing something like `quat + quat` instead of `quat * quat`, using
`Quat::from_xyzw` directly, or when you have significant enough drift
caused by e.g. physics simulation that doesn't normalize rotation. In
general, these would probably cause unexpected results anyway.

I also moved tests around slightly to make `dim2` and `dim3` more
consistent (`dim3` had *two* separate `test` modules for some reason).

In the future, we'll probably want a `Rotation2d` type that would
support the same for `Direction2d`. I considered implementing
`Mul<Mat2>` for `Direction2d`, but that would probably be more
questionable since `Mat2` isn't as clearly associated with rotations as
`Quat` is.
2024-02-01 20:08:24 +00:00
Joona Aalto
d30fdda2c3
Implement approx traits for direction types (#11650)
# Objective

`approx` has traits like
[`AbsDiffEq`](https://docs.rs/approx/latest/approx/trait.AbsDiffEq.html),
[`RelativeEq`](https://docs.rs/approx/latest/approx/trait.RelativeEq.html),
and [`UlpsEq`](https://docs.rs/approx/latest/approx/trait.UlpsEq.html).
Glam implements them for its math types when the `approx` feature is
enabled. Bevy's `Direction2d` and `Direction3d` should implement these
too.

## Solution

Implement the traits. See [how Glam implements them for its own math
types](https://github.com/bitshifter/glam-rs/blob/main/src/features/impl_approx.rs).
For the epsilon values, I use the same as `Vec2`/`Vec3` (just
`f32::EPSILON`).
2024-02-01 19:22:28 +00:00
NiseVoid
e3126a494f
Add Clone to intersection test types (#11640)
# Objective

- Add Clone to RayTest/AabbCast2d/AabbCast3d/CircleCast/SphereCast
2024-02-01 00:54:30 +00:00
NiseVoid
1b98de68fe
Add volume cast intersection tests (#11586)
# Objective

- Add a basic form of shapecasting for bounding volumes

## Solution

- Implement AabbCast2d, AabbCast3d, BoundingCircleCast, and
BoundingSphereCast
- These are really just raycasts, but they modify the volumes the ray is
casting against
- The tests are slightly simpler, since they just use the raycast code
for the heavy lifting
2024-01-31 20:14:15 +00:00
Joona Aalto
a9f061e909
Add Capsule2d primitive (#11585)
# Objective

Currently, the `Capsule` primitive is technically dimension-agnostic in
that it implements both `Primitive2d` and `Primitive3d`. This seems good
on paper, but it can often be useful to have separate 2D and 3D versions
of primitives.

For example, one might want a two-dimensional capsule mesh. We can't
really implement both 2D and 3D meshing for the same type using the
upcoming `Meshable` trait (see #11431). We also currently don't
implement `Bounded2d` for `Capsule`, see
https://github.com/bevyengine/bevy/pull/11336#issuecomment-1890797788.

Having 2D and 3D separate at a type level is more explicit, and also
more consistent with the existing primitives, as there are no other
types that implement both `Primitive2d` and `Primitive3d` at the same
time.

## Solution

Rename `Capsule` to `Capsule3d` and add `Capsule2d`. `Capsule2d`
implements `Bounded2d`.

For now, I went for `Capsule2d` for the sake of consistency and clarity.
Mathematically the more accurate term would be `Stadium` or `Pill` (see
[Wikipedia](https://en.wikipedia.org/wiki/Stadium_(geometry))), but
those might be less obvious to game devs. For reference, Godot has
[`CapsuleShape2D`](https://docs.godotengine.org/en/stable/classes/class_capsuleshape2d.html).
I can rename it if others think the geometrically correct name is better
though.

---

## Changelog

- Renamed `Capsule` to `Capsule3d`
- Added `Capsule2d` with `Bounded2d` implemented

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
2024-01-29 17:52:04 +00:00
Joona Aalto
2bf481c03b
Add Meshable trait and implement meshing for 2D primitives (#11431)
# Objective

The first part of #10569, split up from #11007.

The goal is to implement meshing support for Bevy's new geometric
primitives, starting with 2D primitives. 3D meshing will be added in a
follow-up, and we can consider removing the old mesh shapes completely.

## Solution

Add a `Meshable` trait that primitives need to implement to support
meshing, as suggested by the
[RFC](https://github.com/bevyengine/rfcs/blob/main/rfcs/12-primitive-shapes.md#meshing).

```rust
/// A trait for shapes that can be turned into a [`Mesh`].
pub trait Meshable {
    /// The output of [`Self::mesh`]. This can either be a [`Mesh`]
    /// or a builder used for creating a [`Mesh`].
    type Output;

    /// Creates a [`Mesh`] for a shape.
    fn mesh(&self) -> Self::Output;
}
```

This PR implements it for the following primitives:

- `Circle`
- `Ellipse`
- `Rectangle`
- `RegularPolygon`
- `Triangle2d`

The `mesh` method typically returns a builder-like struct such as
`CircleMeshBuilder`. This is needed to support shape-specific
configuration for things like mesh resolution or UV configuration:

```rust
meshes.add(Circle { radius: 0.5 }.mesh().resolution(64));
```

Note that if no configuration is needed, you can even skip calling
`mesh` because `From<MyPrimitive>` is implemented for `Mesh`:

```rust
meshes.add(Circle { radius: 0.5 });
```

I also updated the `2d_shapes` example to use primitives, and tweaked
the colors to have better contrast against the dark background.

Before:

![Old 2D
shapes](https://github.com/bevyengine/bevy/assets/57632562/f1d8c2d5-55be-495f-8ed4-5890154b81ca)

After:

![New 2D
shapes](https://github.com/bevyengine/bevy/assets/57632562/f166c013-34b8-4752-800a-5517b284d978)

Here you can see the UVs and different facing directions: (taken from
#11007, so excuse the 3D primitives at the bottom left)

![UVs and facing
directions](https://github.com/bevyengine/bevy/assets/57632562/eaf0be4e-187d-4b6d-8fb8-c996ba295a8a)

---

## Changelog

- Added `bevy_render::mesh::primitives` module
- Added `Meshable` trait and implemented it for:
  - `Circle`
  - `Ellipse`
  - `Rectangle`
  - `RegularPolygon`
  - `Triangle2d`
- Implemented `Default` and `Copy` for several 2D primitives
- Updated `2d_shapes` example to use primitives
- Tweaked colors in `2d_shapes` example to have better contrast against
the (new-ish) dark background

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
2024-01-29 16:47:47 +00:00
Joona Aalto
92567490a9
Add more constructors and math helpers for primitive shapes (#10632)
# Objective

Working towards finishing a part of #10572, this PR adds a ton of math
helpers and useful constructors for primitive shapes. I also tried
fixing some naming inconsistencies.

## Solution

- Add mathematical helpers like `area`, `volume`, `perimeter`,
`RegularPolygon::inradius` and so on, trying to cover all core
mathematical properties of each shape
- Add some constructors like `Rectangle::from_corners`,
`Cuboid::from_corners` and `Plane3d::from_points`

I also derived `PartialEq` for the shapes where it's trivial. Primitives
like `Line2d` and `Segment2d` are not trivial because you could argue
that they would be equal if they had an opposite direction.

All mathematical methods have tests with reference values computed by
hand or with external tools.

## Todo

- [x] Add tests to verify that the values from mathematical helpers are
correct

---------

Co-authored-by: IQuick 143 <IQuick143cz@gmail.com>
2024-01-29 16:04:51 +00:00
NiseVoid
8851532890
Add RayTest2d and RayTest3d (#11310)
# Objective

Implement a raycast intersection test for bounding volumes

## Solution

- Implement RayTest2d and RayTest3d types

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: IQuick 143 <IQuick143cz@gmail.com>
2024-01-28 20:12:08 +00:00
NiseVoid
755917fe4b
Derive PartialEq, Serialize, Deserialize and Reflect on primitives (#11514)
# Objective

- Implement common traits on primitives

## Solution

- Derive PartialEq on types that were missing it.
- Derive Copy on small types that were missing it.
- Derive Serialize/Deserialize if the feature on bevy_math is enabled.
- Add a lot of cursed stuff to the bevy_reflect `impls` module.
2024-01-28 14:55:30 +00:00
Joona Aalto
dd4d07dc9c
Add new constructors for Circle and Sphere (#11526)
# Objective

Make APIs more consistent and ergonomic by adding a `new` constructor
for `Circle` and `Sphere`.

This could be seen as a redundant "trivial constructor", but in
practise, it seems valuable to me. I have lots of cases where formatting
becomes ugly because of the lack of a constructor, like this:

```rust
Circle {
    radius: self.radius(),
}
.contains_local_point(centered_pt)
```

With `new`, it'd be formatted much nicer:

```rust
Circle::new(self.radius()).contains_local_point(centered_pt)
```

Of course, this is just one example, but my circle/sphere definitions
very frequently span three or more lines when they could fit on one.

Adding `new` also increases consistency. `Ellipse` has `new` already,
and so does the mesh version of `Circle`.

## Solution

Add a `new` constructor for `Circle` and `Sphere`.
2024-01-26 16:00:59 +00:00
Joona Aalto
6a3b059db9
Implement bounding volume intersections (#11439)
# Objective

#10946 added bounding volume types and an `IntersectsVolume` trait, but
didn't actually implement intersections between bounding volumes.

This PR implements AABB-AABB, circle-circle / sphere-sphere, and
AABB-circle / AABB-sphere intersections.

## Solution

Implement `IntersectsVolume` for bounding volume pairs. I also added
`closest_point` methods to return the closest point on the surface /
inside of bounding volumes. This is used for AABB-circle / AABB-sphere
intersections.

---------

Co-authored-by: IQuick 143 <IQuick143cz@gmail.com>
2024-01-22 17:55:59 +00:00
Doonv
0387331c12
Direction: Rename from_normalized to new_unchecked (#11425)
# Objective

`Direction2d::from_normalized` & `Direction3d::from_normalized` don't
emphasize that importance of the vector being normalized enough.

## Solution

Rename `from_normalized` to `new_unchecked` and add more documentation.

---

`Direction2d` and `Direction3d` were added somewhat recently in
https://github.com/bevyengine/bevy/pull/10466 (after 0.12), so I don't
think documenting the changelog and migration guide is necessary (Since
there is no major previous version to migrate from).

But here it is anyway in case it's needed:

## Changelog

- Renamed `Direction2d::from_normalized` and
`Direction3d::from_normalized` to `new_unchecked`.

## Migration Guide

- Renamed `Direction2d::from_normalized` and
`Direction3d::from_normalized` to `new_unchecked`.

---------

Co-authored-by: Tristan Guichaoua <33934311+tguichaoua@users.noreply.github.com>
Co-authored-by: Joona Aalto <jondolf.dev@gmail.com>
2024-01-20 21:52:09 +00:00
Joona Aalto
c6f45831e9
Add geometric primitives to bevy_math::prelude (#11432)
# Objective

Currently, the `primitives` module is inside of the prelude for
`bevy_math`, but the actual primitives are not. This requires either
importing the shapes everywhere that uses them, or adding the
`primitives::` prefix:

```rust
let rectangle = meshes.add(primitives::Rectangle::new(5.0, 2.5));
```

(Note: meshing isn't actually implemented yet, but it's in #11431)

The primitives are meant to be used for a variety of tasks across
several crates, like for meshing, bounding volumes, gizmos, colliders,
and so on, so I think having them in the prelude is justified. It would
make several common tasks a lot more ergonomic.

```rust
let rectangle = meshes.add(Rectangle::new(5.0, 2.5));
```

## Solution

Add `primitives::*` to `bevy_math::prelude`.

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
2024-01-20 20:15:38 +00:00
Joona Aalto
c31f3aa128
Add Aabb2d::new and Aabb3d::new constructors (#11433)
# Objective

Currently, the only way to create an AABB is to specify its `min` and
`max` coordinates. However, it's often more useful to use the center and
half-size instead.

## Solution

Add `new` constructors for `Aabb2d` and `Aabb3d`.

This:

```rust
let aabb = Aabb3d {
    min: center - half_size,
    max: center + half_size,
}
```

becomes this:

```rust
let aabb = Aabb3d::new(center, half_size);
```

I also made the usage of "half-extents" vs. "half-size" a bit more
consistent.
2024-01-20 20:12:20 +00:00
Joona Aalto
b592a72916
Change Ellipse representation and improve helpers (#11435)
# Objective

Currently, the `Ellipse` primitive is represented by a `half_width` and
`half_height`. To improve consistency (similarly to #11434), it might
make more sense to use a `Vec2` `half_size` instead.

Alternatively, to make the elliptical nature clearer, the properties
could also be called `radius_x` and `radius_y`.

Secondly, `Ellipse::new` currently takes a *full* width and height
instead of two radii. I would expect it to take the half-width and
half-height because ellipses and circles are almost always defined using
radii. I wouldn't expect `Circle::new` to take a diameter (if we had
that method).

## Solution

Change `Ellipse` to store a `half_size` and `new` to take the half-width
and half-height.

I also added a `from_size` method similar to `Rectangle::from_size`, and
added the `semi_minor` and `semi_major` helpers to get the
semi-minor/major radius.
2024-01-20 18:04:53 +00:00
Joona Aalto
6337fb33ff
Improve Rectangle and Cuboid consistency (#11434)
# Objective

The `Rectangle` and `Cuboid` primitives currently use different
representations:

```rust
pub struct Rectangle {
    /// The half width of the rectangle
    pub half_width: f32,
    /// The half height of the rectangle
    pub half_height: f32,
}

pub struct Cuboid {
    /// Half of the width, height and depth of the cuboid
    pub half_extents: Vec3,
}
```

The property names and helpers are also inconsistent. `Cuboid` has
`half_extents`, but it also has a method called `from_size`. Most
existing code also uses "size" instead of "extents".

## Solution

Represent both `Rectangle` and `Cuboid` with `half_size` properties.
2024-01-20 18:03:47 +00:00
Joona Aalto
c62ad4b2c4
Implement bounding volumes for primitive shapes (#11336)
# Objective

Closes #10570.

#10946 added bounding volume types and traits, but didn't use them for
anything yet. This PR implements `Bounded2d` and `Bounded3d` for Bevy's
primitive shapes.

## Solution

Implement `Bounded2d` and `Bounded3d` for primitive shapes. This allows
computing AABBs and bounding circles/spheres for them.

For most shapes, there are several ways of implementing bounding
volumes. I took inspiration from [Parry's bounding
volumes](https://github.com/dimforge/parry/tree/master/src/bounding_volume),
[Inigo Quilez](http://iquilezles.org/articles/diskbbox/), and figured
out the rest myself using geometry. I tried to comment all slightly
non-trivial or unclear math to make it understandable.

Parry uses support mapping (finding the farthest point in some direction
for convex shapes) for some AABBs like cones, cylinders, and line
segments. This involves several quat operations and normalizations, so I
opted for the simpler and more efficient geometric approaches shown in
[Quilez's article](http://iquilezles.org/articles/diskbbox/).

Below you can see some of the bounding volumes working in 2D and 3D.
Note that I can't conveniently add these examples yet because they use
primitive shape meshing, which is still WIP.


https://github.com/bevyengine/bevy/assets/57632562/4465cbc6-285b-4c71-b62d-a2b3ee16f8b4


https://github.com/bevyengine/bevy/assets/57632562/94b4ac84-a092-46d7-b438-ce2e971496a4

---

## Changelog

- Implemented `Bounded2d`/`Bounded3d` for primitive shapes
- Added `from_point_cloud` method for bounding volumes (used by many
bounding implementations)
- Added `point_cloud_2d/3d_center` and `rotate_vec2` utility functions
- Added `RegularPolygon::vertices` method (used in regular polygon AABB
construction)
- Added `Triangle::circumcenter` method (used in triangle bounding
circle construction)
- Added bounding circle/sphere creation from AABBs and vice versa

## Extra

Do we want to implement `Bounded2d` for some "3D-ish" shapes too? For
example, capsules are sort of dimension-agnostic and useful for 2D, so I
think that would be good to implement. But a cylinder in 2D is just a
rectangle, and a cone is a triangle, so they wouldn't make as much sense
to me. A conical frustum would be an isosceles trapezoid, which could be
useful, but I'm not sure if computing the 2D AABB of a 3D frustum makes
semantic sense.
2024-01-18 15:55:36 +00:00
BD103
6f6269e195
Remove Default impl for CubicCurve (#11335)
# Objective

- Implementing `Default` for
[`CubicCurve`](https://docs.rs/bevy/latest/bevy/math/cubic_splines/struct.CubicCurve.html)
does not make sense because it cannot be mutated after creation.
- Closes #11209.
- Alternative to #11211.

## Solution

- Remove `Default` from `CubicCurve`'s derive statement.

Based off of @mockersf comment
(https://github.com/bevyengine/bevy/pull/11211#issuecomment-1880088036):

> CubicCurve can't be updated once created... I would prefer to remove
the Default impl as it doesn't make sense

---

## Changelog

- Removed the `Default` implementation for `CubicCurve`.

## Migration Guide

- Remove `CubicCurve` from any structs that implement `Default`.
- Wrap `CubicCurve` in a new type and provide your own default.

```rust
#[derive(Deref)]
struct MyCubicCurve<P: Point>(pub CubicCurve<P>);

impl Default for MyCubicCurve<Vec2> {
    fn default() -> Self {
        let points = [[
            vec2(-1.0, -20.0),
            vec2(3.0, 2.0),
            vec2(5.0, 3.0),
            vec2(9.0, 8.0),
        ]];

        Self(CubicBezier::new(points).to_curve())
    }
}
```
2024-01-14 04:40:37 +00:00
NiseVoid
c4e479a2d4
Implement bounding volume types (#10946)
# Objective

Implement bounding volume trait and the 4 types from
https://github.com/bevyengine/bevy/issues/10570. I will add intersection
tests in a future PR.

## Solution

Implement mostly everything as written in the issue, except:
- Intersection is no longer a method on the bounding volumes, but a
separate trait.
- I implemented a `visible_area` since it's the most common usecase to
care about the surface that could collide with cast rays.
  - Maybe we want both?

---

## Changelog

- Added bounding volume types to bevy_math

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
2024-01-10 23:18:51 +00:00
irate
ec14e946b8
Update glam, encase and hexasphere (#11082)
Update to `glam` 0.25, `encase` 0.7 and `hexasphere` to 10.0

## Changelog
Added the `FloatExt` trait to the `bevy_math` prelude which adds `lerp`,
`inverse_lerp` and `remap` methods to the `f32` and `f64` types.
2024-01-08 22:58:45 +00:00
Joona Aalto
bcbb7bb9dd
Add new_and_length method to Direction2d and Direction3d (#11172)
# Objective

When creating a normalized direction from a vector, it can be useful to
get both the direction *and* the original length of the vector.

This came up when I was recreating some Parry APIs using bevy_math, and
doing it manually is quite painful. Nalgebra calls this method
[`Unit::try_new_and_get`](https://docs.rs/nalgebra/latest/nalgebra/base/struct.Unit.html#method.try_new_and_get).

## Solution

Add a `new_and_length` method to `Direction2d` and `Direction3d`.

Usage:

```rust
if let Ok((direction, length)) = Direction2d::new_and_length(Vec2::X * 10.0) {
    assert_eq!(direction, Vec2::X);
    assert_eq!(length, 10.0);
}
```

I'm open to different names, couldn't come up with a perfectly clear one
that isn't too long. My reasoning with the current name is that it's
like using `new` and calling `length` on the original vector.
2024-01-08 22:36:56 +00:00
Joona Aalto
0349809420
Add libm feature to bevy_math (#11238)
# Objective

Different platforms use their own implementations of several
mathematical functions (especially transcendental functions like sin,
cos, tan, atan, and so on) to provide hardware-level optimization using
intrinsics. This is good for performance, but bad when you expect
consistent outputs across machines.

[`libm`](https://github.com/rust-lang/libm) is a widely used crate that
provides mathematical functions that don't use intrinsics like `std`
functions. This allows bit-for-bit deterministic math across hardware,
which is crucial for things like cross-platform deterministic physics
simulation.

Glam has the `libm` feature for using [`libm` for the
math](d2871a151b/src/f32/math.rs (L35))
in its own types. This would be nice to expose as a feature in
`bevy_math`.

## Solution

Add `libm` feature to `bevy_math`. We could name it something like
`enhanced-determinism`, but this wouldn't be accurate for the rest of
Bevy, so I think just `libm` is more fitting and explicit.
2024-01-06 22:01:57 +00:00
Joona Aalto
536a7bd810
Add approx feature to bevy_math (#11176)
# Objective

`bevy_math` re-exports Glam, but doesn't have a feature for enabling
`approx` for it. Many projects (including some of Bevy's own crates)
need `approx`, and it'd be nice if you didn't have to manually add Glam
to specify the feature for it.

## Solution

Add an `approx` feature to `bevy_math`.
2024-01-02 18:10:44 +00:00
Joona Aalto
2c5439b25e
Add constants for Direction2d and Direction3d (#11180)
# Objective

I often need a direction along one of the cartesian XYZ axes, and it
currently requires e.g. `Direction2d::from_normalized(Vec2::X)`, which
isn't ideal.

## Solution

Add direction constants that are the same as the ones on Glam types. I
also copied the doc comment format "A unit vector pointing along the ...
axis", but I can change it if there's a better wording for directions.
2024-01-02 17:00:23 +00:00
Joona Aalto
6086d4193e
Implement Neg for Direction2d and Direction3d (#11179)
# Objective

I frequently encounter cases where I need to get the opposite direction.
This currently requires something like
`Direction2d::from_normalized(-*direction)`, which is very inconvenient.

## Solution

Implement `Neg` for `Direction2d` and `Direction3d`.
2024-01-02 16:46:03 +00:00
Doonv
189ceaf0d3
Replace or document ignored doctests (#11040)
# Objective

There are a lot of doctests that are `ignore`d for no documented reason.
And that should be fixed.

## Solution

I searched the bevy repo with the regex ` ```[a-z,]*ignore ` in order to
find all `ignore`d doctests. For each one of the `ignore`d doctests, I
did the following steps:
1. Attempt to remove the `ignored` attribute while still passing the
test. I did this by adding hidden dummy structs and imports.
2. If step 1 doesn't work, attempt to replace the `ignored` attribute
with the `no_run` attribute while still passing the test.
3. If step 2 doesn't work, keep the `ignored` attribute but add
documentation for why the `ignored` attribute was added.

---------

Co-authored-by: François <mockersf@gmail.com>
2024-01-01 16:50:56 +00:00
Olle Lukowski
6b9cd57956
Introduce AspectRatio struct (#10368)
# Objective

- Fix an inconsistency in the calculation of aspect ratio's. 
- Fixes #10288 

## Solution

- Created an intermediate `AspectRatio` struct, as suggested in the
issue. This is currently just used in any places where aspect ratio
calculations happen, to prevent doing it wrong. In my and @mamekoro 's
opinion, it would be better if this was used instead of a normal `f32`
in various places, but I didn't want to make too many changes to begin
with.

## Migration Guide
- Anywhere where you are currently expecting a f32 when getting aspect
ratios, you will now receive a `AspectRatio` struct. this still holds
the same value.

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
2023-12-17 02:01:26 +00:00
Tygyh
645625b789
Replace deprecated elements (#10999)
# Objective

- Replace deprecated elements.

## Solution

- Remove 'std::' from constants.
2023-12-16 23:24:49 +00:00
Joona Aalto
029dd06f7d
Add Direction2d::from_xy and Direction3d::from_xyz (#10882)
# Objective

Make direction construction a bit more ergonomic.

## Solution

Add `Direction2d::from_xy` and `Direction3d::from_xyz`, similar to
`Transform::from_xyz`:

```rust
let dir2 = Direction2d::from_xy(0.5, 0.5).unwrap();
let dir3 = Direction3d::from_xyz(0.5, 0.5, 0.5).unwrap();
```

This can be a bit cleaner than using `new`:

```rust
let dir2 = Direction2d::new(Vec2::new(0.5, 0.5)).unwrap();
let dir3 = Direction3d::new(Vec3::new(0.5, 0.5, 0.5)).unwrap();
```
2023-12-14 14:56:07 +00:00
Joona Aalto
d9aac887b5
Split Ray into Ray2d and Ray3d and simplify plane construction (#10856)
# Objective

A better alternative version of #10843.

Currently, Bevy has a single `Ray` struct for 3D. To allow better
interoperability with Bevy's primitive shapes (#10572) and some third
party crates (that handle e.g. spatial queries), it would be very useful
to have separate versions for 2D and 3D respectively.

## Solution

Separate `Ray` into `Ray2d` and `Ray3d`. These new structs also take
advantage of the new primitives by using `Direction2d`/`Direction3d` for
the direction:

```rust
pub struct Ray2d {
    pub origin: Vec2,
    pub direction: Direction2d,
}

pub struct Ray3d {
    pub origin: Vec3,
    pub direction: Direction3d,
}
```

and by using `Plane2d`/`Plane3d` in `intersect_plane`:

```rust
impl Ray2d {
    // ...
    pub fn intersect_plane(&self, plane_origin: Vec2, plane: Plane2d) -> Option<f32> {
        // ...
    }
}
```

---

## Changelog

### Added

- `Ray2d` and `Ray3d`
- `Ray2d::new` and `Ray3d::new` constructors
- `Plane2d::new` and `Plane3d::new` constructors

### Removed

- Removed `Ray` in favor of `Ray3d`

### Changed

- `direction` is now a `Direction2d`/`Direction3d` instead of a vector,
which provides guaranteed normalization
- `intersect_plane` now takes a `Plane2d`/`Plane3d` instead of just a
vector for the plane normal
- `Direction2d` and `Direction3d` now derive `Serialize` and
`Deserialize` to preserve ray (de)serialization

## Migration Guide

`Ray` has been renamed to `Ray3d`.

### Ray creation

Before:

```rust
Ray {
    origin: Vec3::ZERO,
    direction: Vec3::new(0.5, 0.6, 0.2).normalize(),
}
```

After:

```rust
// Option 1:
Ray3d {
    origin: Vec3::ZERO,
    direction: Direction3d::new(Vec3::new(0.5, 0.6, 0.2)).unwrap(),
}

// Option 2:
Ray3d::new(Vec3::ZERO, Vec3::new(0.5, 0.6, 0.2))
```

### Plane intersections

Before:

```rust
let result = ray.intersect_plane(Vec2::X, Vec2::Y);
```

After:

```rust
let result = ray.intersect_plane(Vec2::X, Plane2d::new(Vec2::Y));
```
2023-12-06 14:09:04 +00:00
Joona Aalto
f683b802f1
Impl TryFrom vector for directions and add InvalidDirectionError (#10884)
# Objective

Implement `TryFrom<Vec2>`/`TryFrom<Vec3>` for direction primitives as
considered in #10857.

## Solution

Implement `TryFrom` for the direction primitives.

These are all equivalent:

```rust
let dir2d = Direction2d::try_from(Vec2::new(0.5, 0.5)).unwrap();
let dir2d = Vec2::new(0.5, 0.5).try_into().unwrap(); // (assumes that the type is inferred)
let dir2d = Direction2d::new(Vec2::new(0.5, 0.5)).unwrap();
```

For error cases, an `Err(InvalidDirectionError)` is returned. It
contains the type of failure:

```rust
/// An error indicating that a direction is invalid.
#[derive(Debug, PartialEq)]
pub enum InvalidDirectionError {
    /// The length of the direction vector is zero or very close to zero.
    Zero,
    /// The length of the direction vector is `std::f32::INFINITY`.
    Infinite,
    /// The length of the direction vector is `NaN`.
    NaN,
}
```
2023-12-06 00:05:37 +00:00
irate
83ee6de1da
Remove From implementations from the direction types (#10857)
This removes the `From<Vec2/3>` implementations for the direction types.
It doesn't seem right to have when it only works if the vector is
nonzero and finite and produces NaN otherwise.

Added `Direction2d/3d::new` which uses `Vec2/3::try_normalize` to
guarantee it returns either a valid direction or `None`.

This should make it impossible to create an invalid direction, which I
think was the intention with these types.
2023-12-05 02:44:27 +00:00
Joona Aalto
897b13bf9d
Use minor and major radii for Torus primitive shape (#10643)
# Objective

First, some terminology:

- **Minor radius**: The radius of the tube of a torus, i.e. the
"half-thickness"
- **Major radius**: The distance from the center of the tube to the
center of the torus
- **Inner radius**: The radius of the hole (if it exists), `major_radius
- minor_radius`
- **Outer radius**: The radius of the overall shape, `major_radius +
minor_radius`
- **Ring torus**: The familiar donut shape with a hole in the center,
`major_radius > minor_radius`
- **Horn torus**: A torus that doesn't have a hole but also isn't
self-intersecting, `major_radius == minor_radius`
- **Spindle torus**: A self-intersecting torus, `major_radius <
minor_radius`

Different tori from [Wikipedia](https://en.wikipedia.org/wiki/Torus),
where *R* is the major radius and *r* is the minor radius:


![kuva](https://github.com/bevyengine/bevy/assets/57632562/53ead786-2402-43a7-ae8a-5720e6e54dcc)

Currently, Bevy's torus is represented by a `radius` and `ring_radius`.
I believe these correspond to the outer radius and minor radius, but
they are rather confusing and inconsistent names, and they make the
assumption that the torus always has a ring.

I also couldn't find any other big engines using this representation;
[Godot](https://docs.godotengine.org/en/stable/classes/class_torusmesh.html)
and [Unity
ProBuilder](https://docs.unity3d.com/Packages/com.unity.probuilder@4.0/manual/Torus.html)
use the inner and outer radii, while
[Unreal](https://docs.unrealengine.com/5.3/en-US/BlueprintAPI/GeometryScript/Primitives/AppendTorus/)
uses the minor and major radii.
[Blender](https://docs.blender.org/manual/en/latest/modeling/meshes/primitives.html#torus)
supports both, but defaults to minor/major.

Bevy's `Torus` primitive should have an efficient, consistent, clear and
flexible representation, and the current `radius` and `ring_radius`
properties are not ideal for that.

## Solution

Change `Torus` to be represented by a `minor_radius` and `major_radius`.

- Mathematically correct and consistent
- Flexible, not restricted to ring tori
- Computations and conversions are efficient
  - `inner_radius = major_radius - minor_radius`
  - `outer_radius = major_radius + minor_radius`
- Mathematical formulae for things like area and volume rely on the
minor and major radii, no conversion needed

Perhaps the primary issue with this representation is that "minor
radius" and "major radius" are rather mathematical, and an inner/outer
radius can be more intuitive in some cases. However, this can be
mitigated with constructors and helpers.
2023-11-21 01:49:35 +00:00
Joona Aalto
e1c8d60f91
Add winding order for Triangle2d (#10620)
# Objective

This PR adds some helpers for `Triangle2d` to work with its winding
order. This could also be extended to polygons (and `Triangle3d` once
it's added).

## Solution

- Add `WindingOrder` enum with `Clockwise`, `Counterclockwise` and
`Invalid` variants
- `Invalid` is for cases where the winding order can not be reliably
computed, i.e. the points lie on a single line and the area is zero
- Add `Triangle2d::winding_order` method that uses a signed surface area
to determine the winding order
- Add `Triangle2d::reverse` method that reverses the winding order by
swapping the second and third vertices

The API looks like this:

```rust
let mut triangle = Triangle2d::new(
    Vec2::new(0.0, 2.0),
    Vec2::new(-0.5, -1.2),
    Vec2::new(-1.0, -1.0),
);
assert_eq!(triangle.winding_order(), WindingOrder::Clockwise);

// Reverse winding order
triangle.reverse();
assert_eq!(triangle.winding_order(), WindingOrder::Counterclockwise);
```

I also added tests to make sure the methods work correctly. For now,
they live in the same file as the primitives.

## Open questions

- Should it be `Counterclockwise` or `CounterClockwise`? The first one
is more correct but perhaps a bit less readable. Counter-clockwise is
also a valid spelling, but it seems to be a lot less common than
counterclockwise.
- Is `WindingOrder::Invalid` a good name? Parry uses
`TriangleOrientation::Degenerate`, but I'm not a huge fan, at least as a
non-native English speaker. Any better suggestions?
- Is `WindingOrder` fine in `bevy_math::primitives`? It's not specific
to a dimension, so I put it there for now.
2023-11-20 09:47:05 +00:00