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switched the magnitude function to use the alpha max + beta min algorithm

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This commit is contained in:
Corwin Kuiper 2021-12-06 19:49:27 +00:00
parent f5ae6ac579
commit 9a25274bb0
1 changed files with 9 additions and 8 deletions
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17
agb/src/number.rs
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@ -378,13 +378,6 @@ impl<I: FixedWidthSignedInteger, const N: usize> Num<I, N> {
}
}
impl<const N: usize> Num<i32, N> {
pub fn sqrt(self) -> Self {
assert_eq!(N % 2, 0, "N must be even to be able to square root");
Self(syscall::sqrt(self.0) << (N / 2))
}
}
#[test_case]
fn test_numbers(_gba: &mut super::Gba) {
// test addition
@ -696,9 +689,17 @@ impl<const N: usize> Vector2D<Num<i32, N>> {
self.x.abs() + self.y.abs()
}
// calculates the magnitude of a vector using the alpha max plus beta min
// algorithm https://en.wikipedia.org/wiki/Alpha_max_plus_beta_min_algorithm
// this has a maximum error of less than 4% of the true magnitude, probably
// depending on the size of your fixed point approximation
pub fn magnitude(self) -> Num<i32, N> {
self.magnitude_squared().sqrt()
let max = core::cmp::max(self.x, self.y);
let min = core::cmp::min(self.x, self.y);
max * num!(0.960433870103) + min * num!(0.397824734759)
}
pub fn normalise(self) -> Self {
self / self.magnitude()
}