2021-08-14 19:21:36 +00:00
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[package]
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name = "bevy_math"
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2024-02-21 20:58:59 +00:00
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version = "0.14.0-dev"
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2021-10-27 00:12:14 +00:00
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edition = "2021"
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2021-08-14 19:21:36 +00:00
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description = "Provides math functionality for Bevy Engine"
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homepage = "https://bevyengine.org"
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repository = "https://github.com/bevyengine/bevy"
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license = "MIT OR Apache-2.0"
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keywords = ["bevy"]
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[dependencies]
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2024-05-02 18:42:34 +00:00
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glam = { version = "0.27", features = ["bytemuck"] }
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2024-02-28 17:18:42 +00:00
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thiserror = "1.0"
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2022-10-31 16:12:15 +00:00
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serde = { version = "1", features = ["derive"], optional = true }
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Add `Rotation2d` (#11658)
# Objective
Rotating vectors is a very common task. It is required for a variety of
things both within Bevy itself and in many third party plugins, for
example all over physics and collision detection, and for things like
Bevy's bounding volumes and several gizmo implementations.
For 3D, we can do this using a `Quat`, but for 2D, we do not have a
clear and efficient option. `Mat2` can be used for rotating vectors if
created using `Mat2::from_angle`, but this is not obvious to many users,
it doesn't have many rotation helpers, and the type does not give any
guarantees that it represents a valid rotation.
We should have a proper type for 2D rotations. In addition to allowing
for potential optimization, it would allow us to have a consistent and
explicitly documented representation used throughout the engine, i.e.
counterclockwise and in radians.
## Representation
The mathematical formula for rotating a 2D vector is the following:
```
new_x = x * cos - y * sin
new_y = x * sin + y * cos
```
Here, `sin` and `cos` are the sine and cosine of the rotation angle.
Computing these every time when a vector needs to be rotated can be
expensive, so the rotation shouldn't be just an `f32` angle. Instead, it
is often more efficient to represent the rotation using the sine and
cosine of the angle instead of storing the angle itself. This can be
freely passed around and reused without unnecessary computations.
The two options are either a 2x2 rotation matrix or a unit complex
number where the cosine is the real part and the sine is the imaginary
part. These are equivalent for the most part, but the unit complex
representation is a bit more memory efficient (two `f32`s instead of
four), so I chose that. This is like Nalgebra's
[`UnitComplex`](https://docs.rs/nalgebra/latest/nalgebra/geometry/type.UnitComplex.html)
type, which can be used for the
[`Rotation2`](https://docs.rs/nalgebra/latest/nalgebra/geometry/type.Rotation2.html)
type.
## Implementation
Add a `Rotation2d` type represented as a unit complex number:
```rust
/// A counterclockwise 2D rotation in radians.
///
/// The rotation angle is wrapped to be within the `]-pi, pi]` range.
pub struct Rotation2d {
/// The cosine of the rotation angle in radians.
///
/// This is the real part of the unit complex number representing the rotation.
pub cos: f32,
/// The sine of the rotation angle in radians.
///
/// This is the imaginary part of the unit complex number representing the rotation.
pub sin: f32,
}
```
Using it is similar to using `Quat`, but in 2D:
```rust
let rotation = Rotation2d::radians(PI / 2.0);
// Rotate vector (also works on Direction2d!)
assert_eq!(rotation * Vec2::X, Vec2::Y);
// Get angle as degrees
assert_eq!(rotation.as_degrees(), 90.0);
// Getting sin and cos is free
let (sin, cos) = rotation.sin_cos();
// "Subtract" rotations
let rotation2 = Rotation2d::FRAC_PI_4; // there are constants!
let diff = rotation * rotation2.inverse();
assert_eq!(diff.as_radians(), PI / 4.0);
// This is equivalent to the above
assert_eq!(rotation2.angle_between(rotation), PI / 4.0);
// Lerp
let rotation1 = Rotation2d::IDENTITY;
let rotation2 = Rotation2d::FRAC_PI_2;
let result = rotation1.lerp(rotation2, 0.5);
assert_eq!(result.as_radians(), std::f32::consts::FRAC_PI_4);
// Slerp
let rotation1 = Rotation2d::FRAC_PI_4);
let rotation2 = Rotation2d::degrees(-180.0); // we can use degrees too!
let result = rotation1.slerp(rotation2, 1.0 / 3.0);
assert_eq!(result.as_radians(), std::f32::consts::FRAC_PI_2);
```
There's also a `From<f32>` implementation for `Rotation2d`, which means
that methods can still accept radians as floats if the argument uses
`impl Into<Rotation2d>`. This means that adding `Rotation2d` shouldn't
even be a breaking change.
---
## Changelog
- Added `Rotation2d`
- Bounding volume methods now take an `impl Into<Rotation2d>`
- Gizmo methods with rotation now take an `impl Into<Rotation2d>`
## Future use cases
- Collision detection (a type like this is quite essential considering
how common vector rotations are)
- `Transform` helpers (e.g. return a 2D rotation about the Z axis from a
`Transform`)
- The rotation used for `Transform2d` (#8268)
- More gizmos, maybe meshes... everything in 2D that uses rotation
---------
Co-authored-by: Tristan Guichaoua <33934311+tguichaoua@users.noreply.github.com>
Co-authored-by: Robert Walter <robwalter96@gmail.com>
Co-authored-by: IQuick 143 <IQuick143cz@gmail.com>
2024-03-11 19:11:57 +00:00
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libm = { version = "0.2", optional = true }
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2024-02-01 19:22:28 +00:00
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approx = { version = "0.5", optional = true }
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2024-03-17 14:48:16 +00:00
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rand = { version = "0.8", features = [
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"alloc",
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], default-features = false, optional = true }
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2022-09-03 03:02:04 +00:00
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2024-01-29 16:04:51 +00:00
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[dev-dependencies]
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approx = "0.5"
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2024-03-17 14:48:16 +00:00
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# Supply rngs for examples and tests
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rand = "0.8"
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rand_chacha = "0.3"
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2024-03-27 20:48:20 +00:00
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# Enable the approx feature when testing.
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bevy_math = { path = ".", version = "0.14.0-dev", features = ["approx"] }
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2024-01-29 16:04:51 +00:00
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2022-09-03 03:02:04 +00:00
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[features]
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2024-03-17 14:48:16 +00:00
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default = ["rand"]
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2023-03-28 20:18:50 +00:00
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serialize = ["dep:serde", "glam/serde"]
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2024-01-02 18:10:44 +00:00
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# Enable approx for glam types to approximate floating point equality comparisons and assertions
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2024-02-01 19:22:28 +00:00
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approx = ["dep:approx", "glam/approx"]
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2022-09-03 03:02:04 +00:00
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# Enable interoperation of glam types with mint-compatible libraries
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mint = ["glam/mint"]
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2024-01-06 22:01:57 +00:00
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# Enable libm mathematical functions for glam types to ensure consistent outputs
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# across platforms at the cost of losing hardware-level optimization using intrinsics
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Add `Rotation2d` (#11658)
# Objective
Rotating vectors is a very common task. It is required for a variety of
things both within Bevy itself and in many third party plugins, for
example all over physics and collision detection, and for things like
Bevy's bounding volumes and several gizmo implementations.
For 3D, we can do this using a `Quat`, but for 2D, we do not have a
clear and efficient option. `Mat2` can be used for rotating vectors if
created using `Mat2::from_angle`, but this is not obvious to many users,
it doesn't have many rotation helpers, and the type does not give any
guarantees that it represents a valid rotation.
We should have a proper type for 2D rotations. In addition to allowing
for potential optimization, it would allow us to have a consistent and
explicitly documented representation used throughout the engine, i.e.
counterclockwise and in radians.
## Representation
The mathematical formula for rotating a 2D vector is the following:
```
new_x = x * cos - y * sin
new_y = x * sin + y * cos
```
Here, `sin` and `cos` are the sine and cosine of the rotation angle.
Computing these every time when a vector needs to be rotated can be
expensive, so the rotation shouldn't be just an `f32` angle. Instead, it
is often more efficient to represent the rotation using the sine and
cosine of the angle instead of storing the angle itself. This can be
freely passed around and reused without unnecessary computations.
The two options are either a 2x2 rotation matrix or a unit complex
number where the cosine is the real part and the sine is the imaginary
part. These are equivalent for the most part, but the unit complex
representation is a bit more memory efficient (two `f32`s instead of
four), so I chose that. This is like Nalgebra's
[`UnitComplex`](https://docs.rs/nalgebra/latest/nalgebra/geometry/type.UnitComplex.html)
type, which can be used for the
[`Rotation2`](https://docs.rs/nalgebra/latest/nalgebra/geometry/type.Rotation2.html)
type.
## Implementation
Add a `Rotation2d` type represented as a unit complex number:
```rust
/// A counterclockwise 2D rotation in radians.
///
/// The rotation angle is wrapped to be within the `]-pi, pi]` range.
pub struct Rotation2d {
/// The cosine of the rotation angle in radians.
///
/// This is the real part of the unit complex number representing the rotation.
pub cos: f32,
/// The sine of the rotation angle in radians.
///
/// This is the imaginary part of the unit complex number representing the rotation.
pub sin: f32,
}
```
Using it is similar to using `Quat`, but in 2D:
```rust
let rotation = Rotation2d::radians(PI / 2.0);
// Rotate vector (also works on Direction2d!)
assert_eq!(rotation * Vec2::X, Vec2::Y);
// Get angle as degrees
assert_eq!(rotation.as_degrees(), 90.0);
// Getting sin and cos is free
let (sin, cos) = rotation.sin_cos();
// "Subtract" rotations
let rotation2 = Rotation2d::FRAC_PI_4; // there are constants!
let diff = rotation * rotation2.inverse();
assert_eq!(diff.as_radians(), PI / 4.0);
// This is equivalent to the above
assert_eq!(rotation2.angle_between(rotation), PI / 4.0);
// Lerp
let rotation1 = Rotation2d::IDENTITY;
let rotation2 = Rotation2d::FRAC_PI_2;
let result = rotation1.lerp(rotation2, 0.5);
assert_eq!(result.as_radians(), std::f32::consts::FRAC_PI_4);
// Slerp
let rotation1 = Rotation2d::FRAC_PI_4);
let rotation2 = Rotation2d::degrees(-180.0); // we can use degrees too!
let result = rotation1.slerp(rotation2, 1.0 / 3.0);
assert_eq!(result.as_radians(), std::f32::consts::FRAC_PI_2);
```
There's also a `From<f32>` implementation for `Rotation2d`, which means
that methods can still accept radians as floats if the argument uses
`impl Into<Rotation2d>`. This means that adding `Rotation2d` shouldn't
even be a breaking change.
---
## Changelog
- Added `Rotation2d`
- Bounding volume methods now take an `impl Into<Rotation2d>`
- Gizmo methods with rotation now take an `impl Into<Rotation2d>`
## Future use cases
- Collision detection (a type like this is quite essential considering
how common vector rotations are)
- `Transform` helpers (e.g. return a 2D rotation about the Z axis from a
`Transform`)
- The rotation used for `Transform2d` (#8268)
- More gizmos, maybe meshes... everything in 2D that uses rotation
---------
Co-authored-by: Tristan Guichaoua <33934311+tguichaoua@users.noreply.github.com>
Co-authored-by: Robert Walter <robwalter96@gmail.com>
Co-authored-by: IQuick 143 <IQuick143cz@gmail.com>
2024-03-11 19:11:57 +00:00
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libm = ["dep:libm", "glam/libm"]
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2023-03-28 20:18:50 +00:00
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# Enable assertions to check the validity of parameters passed to glam
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glam_assert = ["glam/glam-assert"]
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2023-10-22 23:01:28 +00:00
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# Enable assertions in debug builds to check the validity of parameters passed to glam
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debug_glam_assert = ["glam/debug-glam-assert"]
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2024-03-17 14:48:16 +00:00
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# Enable the rand dependency for shape_sampling
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Random sampling of directions and quaternions (#12857)
# Objective
Augment Bevy's random sampling capabilities by providing good tools for
producing random directions and rotations.
## Solution
The `rand` crate has a natural tool for providing `Distribution`s whose
output is a type that doesn't require any additional data to sample
values — namely,
[`Standard`](https://docs.rs/rand/latest/rand/distributions/struct.Standard.html).
Here, our existing `ShapeSample` implementations have been put to good
use in providing these, resulting in patterns like the following:
```rust
// Using thread-local rng
let random_direction1: Dir3 = random();
// Using an explicit rng
let random_direction2: Dir3 = rng.gen();
// Using an explicit rng coupled explicitly with Standard
let random_directions: Vec<Dir3> = rng.sample_iter(Standard).take(5).collect();
```
Furthermore, we have introduced a trait `FromRng` which provides sugar
for `rng.gen()` that is more namespace-friendly (in this author's
opinion):
```rust
let random_direction = Dir3::from_rng(rng);
```
The types this has been implemented for are `Dir2`, `Dir3`, `Dir3A`, and
`Quat`. Notably, `Quat` uses `glam`'s implementation rather than an
in-house one, and as a result, `bevy_math`'s "rand" feature now enables
that of `glam`.
---
## Changelog
- Created `standard` submodule in `sampling` to hold implementations and
other items related to the `Standard` distribution.
- "rand" feature of `bevy_math` now enables that of `glam`.
---
## Discussion
From a quick glance at `Quat`'s distribution implementation in `glam`, I
am a bit suspicious, since it is simple and doesn't match any algorithm
that I came across in my research. I will do a little more digging as a
follow-up to this and see if it's actually uniform (maybe even using
those tools I wrote — what a thrill).
As an aside, I'd also like to say that I think
[`Distribution`](https://docs.rs/rand/latest/rand/distributions/trait.Distribution.html)
is really, really good. It integrates with distributions provided
externally (e.g. in `rand` itself and its extensions) along with doing a
good job of isolating the source of randomness, so that output can be
reliably reproduced if need be. Finally, `Distribution::sample_iter` is
quite good for ergonomically acquiring lots of random values. At one
point I found myself writing traits to describe random sampling and
essentially reinvented this one. I just think it's good, and I think
it's worth centralizing around to a significant extent.
2024-04-04 23:13:00 +00:00
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rand = ["dep:rand", "glam/rand"]
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2023-11-18 20:58:48 +00:00
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[lints]
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workspace = true
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2024-03-08 20:03:09 +00:00
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[package.metadata.docs.rs]
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2024-03-23 02:22:52 +00:00
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rustdoc-args = ["-Zunstable-options", "--cfg", "docsrs"]
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2024-03-08 20:03:09 +00:00
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all-features = true
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