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Made color conversion way more accurate.

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Acrimon 2020-01-13 16:38:10 +01:00
parent a06511e413
commit af8468315d
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GPG Key ID: 79B55D369EAD2A06
1 changed files with 26 additions and 14 deletions
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40
common/src/util/mod.rs
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@ -7,28 +7,40 @@ lazy_static::lazy_static! {
use vek::{Mat3, Rgb, Rgba, Vec3};
/// This is a fast approximation of powf. This should only be used when minor accuracy loss is acceptable.
#[inline(always)]
#[allow(unsafe_code)]
fn approx_powf(b: f32, e: f32) -> f32 {
unsafe {
let b = b as f64;
let e = e as f64;
union Swagger {
f: f64,
a: [i32; 2],
}
let mut b = Swagger { f: b };
b.a[1] = (e * (b.a[1] as f64 - 1072632447.0) + 1072632447.0) as i32;
b.a[0] = 0;
b.f as f32
unsafe fn approx_powf_internal(mut a: f64, b: f64) -> f64 {
let mut e = b as i32;
union Swagger {
d: f64,
x: [i32; 2],
}
let mut u = Swagger { d: a };
u.x[1] = ((b - e as f64) * (u.x[1] as f64 - 1072632447.0) + 1072632447.0) as i32;
u.x[0] = 0;
let mut r = 1.0_f64;
while e > 0 {
if e & 1 > 0 {
r *= a;
}
a *= a;
e >>= 1;
}
return r * u.d;
}
#[inline(always)]
#[allow(unsafe_code)]
fn approx_powf(a: f32, b: f32) -> f32 {
unsafe { approx_powf_internal(a as f64, b as f64) as f32 }
}
#[cfg(test)]
mod approx_powf_tests {
fn close_ei(a: f32, b: f32) -> bool {
(a - b < 1.0 && a - b > 0.0) || (b - a < 1.0 && b - a > 0.0)
const ACCEPTABLE_DIFF: f32 = 0.05;
(a - b < ACCEPTABLE_DIFF && a - b > 0.0) || (b - a < ACCEPTABLE_DIFF && b - a > 0.0)
}
#[test]