| // Copyright 2013 The Servo Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| /// Trait for basic trigonometry functions, so they can be used on generic numeric types |
| pub trait Trig { |
| fn sin(self) -> Self; |
| fn cos(self) -> Self; |
| fn tan(self) -> Self; |
| fn fast_atan2(y: Self, x: Self) -> Self; |
| fn degrees_to_radians(deg: Self) -> Self; |
| fn radians_to_degrees(rad: Self) -> Self; |
| } |
| |
| macro_rules! trig { |
| ($ty:ident) => ( |
| impl Trig for $ty { |
| #[inline] |
| fn sin(self) -> $ty { self.sin() } |
| #[inline] |
| fn cos(self) -> $ty { self.cos() } |
| #[inline] |
| fn tan(self) -> $ty { self.tan() } |
| |
| /// A slightly faster approximation of `atan2`. |
| /// |
| /// Note that it does not deal with the case where both x and y are 0. |
| #[inline] |
| fn fast_atan2(y: $ty, x: $ty) -> $ty { |
| // This macro is used with f32 and f64 and clippy warns about the extra |
| // precision with f32. |
| #![cfg_attr(feature = "cargo-clippy", allow(excessive_precision))] |
| |
| // See https://math.stackexchange.com/questions/1098487/atan2-faster-approximation#1105038 |
| use core::$ty::consts; |
| let x_abs = x.abs(); |
| let y_abs = y.abs(); |
| let a = x_abs.min(y_abs) / x_abs.max(y_abs); |
| let s = a * a; |
| let mut result = ((-0.046_496_474_9 * s + 0.159_314_22) * s - 0.327_622_764) * s * a + a; |
| if y_abs > x_abs { |
| result = consts::FRAC_PI_2 - result; |
| } |
| if x < 0.0 { |
| result = consts::PI - result |
| } |
| if y < 0.0 { |
| result = -result |
| } |
| |
| result |
| } |
| |
| #[inline] |
| fn degrees_to_radians(deg: Self) -> Self { |
| deg.to_radians() |
| } |
| |
| #[inline] |
| fn radians_to_degrees(rad: Self) -> Self { |
| rad.to_degrees() |
| } |
| } |
| ) |
| } |
| |
| trig!(f32); |
| trig!(f64); |