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use crate::{access, clone, math::Dir3};
pub struct Crossing {
ref_prob: f64,
ref_dir: Dir3,
trans_dir: Option<Dir3>,
}
impl Crossing {
clone!(ref_prob, f64);
access!(ref_dir, Dir3);
access!(trans_dir, Option<Dir3>);
#[inline]
#[must_use]
pub fn new(inc: &Dir3, norm: &Dir3, n_curr: f64, n_next: f64) -> Self {
debug_assert!(n_curr >= 1.0);
debug_assert!(n_next >= 1.0);
debug_assert!(inc.dot(norm) < 0.0);
let ci = -inc.dot(norm);
let n = n_curr / n_next;
let crit_ang = if n_curr <= n_next {
None
} else {
Some((n_next / n_curr).asin())
};
let (ref_prob, trans_dir) = if crit_ang.is_some() && (ci.acos() >= crit_ang.unwrap()) {
(1.0, None)
} else {
let s2t = (n * n) * (1.0 - (ci * ci));
let ct = (1.0 - s2t).sqrt();
(
Self::init_ref_prob(n_curr, n_next, ci, ct),
Some(Self::init_trans_dir(inc, norm, n, ci, ct)),
)
};
Self {
ref_prob,
ref_dir: Self::init_ref_dir(inc, norm, ci),
trans_dir,
}
}
#[inline]
#[must_use]
fn init_ref_prob(n1: f64, n2: f64, ci: f64, ct: f64) -> f64 {
debug_assert!(n1 >= 0.0);
debug_assert!(n2 >= 0.0);
let n1_c_i = n1 * ci;
let n2_c_t = n2 * ct;
let r_norm_sqrt = (n1_c_i - n2_c_t) / (n1_c_i + n2_c_t);
let r_norm = r_norm_sqrt * r_norm_sqrt;
let n2_c_i = n2 * ci;
let n1_c_t = n1 * ct;
let r_tran_sqrt = (n2_c_i - n1_c_t) / (n2_c_i + n1_c_t);
let r_tran = r_tran_sqrt * r_tran_sqrt;
(r_norm + r_tran) / 2.0
}
#[inline]
#[must_use]
fn init_ref_dir(inc: &Dir3, norm: &Dir3, ci: f64) -> Dir3 {
Dir3::new_unchecked(inc.into_inner() + (2.0 * ci * norm.into_inner()))
}
#[inline]
#[must_use]
pub fn calc_ref_dir(inc: &Dir3, norm: &Dir3) -> Dir3 {
Self::init_ref_dir(inc, norm, -inc.dot(norm))
}
#[inline]
#[must_use]
fn init_trans_dir(inc: &Dir3, norm: &Dir3, n: f64, ci: f64, ct: f64) -> Dir3 {
Dir3::new_unchecked((n * inc.into_inner()) + ((n * ci) - ct) * norm.into_inner())
}
#[inline]
#[must_use]
pub fn trans_prob(&self) -> f64 {
1.0 - self.ref_prob
}
}