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// 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 {
num_traits::Float::sin(self)
}
#[inline]
fn cos(self) -> $ty {
num_traits::Float::cos(self)
}
#[inline]
fn tan(self) -> $ty {
num_traits::Float::tan(self)
}
/// 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 = num_traits::Float::abs(x);
let y_abs = num_traits::Float::abs(y);
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);
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