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emath: Add some new geometric angle calculation functions to Pos2

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Varphone Wong
2024-03-11 09:54:20 +08:00
parent 83ee315c3c
commit 5b7af394b0
1 changed files with 71 additions and 0 deletions
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71
crates/emath/src/pos2.rs
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@@ -134,6 +134,77 @@ impl Pos2 {
}
}
/// Calculate the angle between two points, originating from this point to points `a` and `b`.
///
/// The result is in the range `[-pi, pi]`.
///
/// # Example
///
/// ```
/// # use emath::*;
/// let a = pos2(0.0, 0.0);
/// let b = pos2(1.0, 0.0);
/// let c = pos2(0.0, 1.0);
/// assert_eq!(a.angle_between(b, c), std::f32::consts::FRAC_PI_2);
/// let c = pos2(1.0, 1.0);
/// assert_eq!(a.angle_between(b, c), std::f32::consts::FRAC_PI_4);
/// let c = pos2(-1.0, 0.0);
/// assert_eq!(a.angle_between(b, c), std::f32::consts::PI);
/// ```
#[inline]
pub fn angle_between(self, a: Self, b: Self) -> f32 {
let va = a - self;
let vb = b - self;
let dot_product = va.dot(vb);
let magnitude_product = va.length() * vb.length();
(dot_product / magnitude_product).acos()
}
/// Calculate the angle from the origin to this point.
///
/// The result is in the range `[-pi, pi]`.
///
/// # Example
///
/// ```
/// # use emath::*;
/// let p = pos2(1.0, 1.0);
/// assert_eq!(p.angle_from_origin(), std::f32::consts::FRAC_PI_4);
/// let p = pos2(-1.0, 1.0);
/// assert_eq!(p.angle_from_origin(), std::f32::consts::PI - std::f32::consts::FRAC_PI_4);
/// let p = pos2(1.0, -1.0);
/// assert_eq!(p.angle_from_origin(), -std::f32::consts::FRAC_PI_4);
/// let p = pos2(-1.0, -1.0);
/// assert_eq!(p.angle_from_origin(), -std::f32::consts::PI + std::f32::consts::FRAC_PI_4);
/// ```
#[inline]
pub fn angle_from_origin(self) -> f32 {
self.y.atan2(self.x)
}
/// Calculate the angle from this point to another point.
///
/// The result is in the range `[-pi, pi]`.
///
/// # Example
///
/// ```
/// # use emath::*;
/// let a = pos2(0.0, 0.0);
/// let b = pos2(1.0, 0.0);
/// assert_eq!(a.angle_to(b), 0.0);
/// let b = pos2(0.0, 1.0);
/// assert_eq!(a.angle_to(b), std::f32::consts::FRAC_PI_2);
/// let b = pos2(-1.0, 0.0);
/// assert_eq!(a.angle_to(b), std::f32::consts::PI);
/// let b = pos2(0.0, -1.0);
/// assert_eq!(a.angle_to(b), -std::f32::consts::FRAC_PI_2);
/// ```
#[inline]
pub fn angle_to(self, other: Self) -> f32 {
(other.y - self.y).atan2(other.x - self.x)
}
#[inline]
pub fn distance(self, other: Self) -> f32 {
(self - other).length()