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use {Voxel, FloatNum, SignedNum, sort_voxels, collect_vec_deque};
use std::collections::VecDeque;
#[inline]
fn compare<T: SignedNum>(a: T, b: T) -> T {
if a > b { T::one() } else if a == b { T::zero() } else { -T::one() }
}
#[inline]
fn round<I: FloatNum, O: SignedNum>(voxel: Voxel<I>) -> Voxel<O> {
(O::cast(voxel.0.round()), O::cast(voxel.1.round()), O::cast(voxel.2.round()))
}
pub struct WalkVoxels<I, O> {
voxel: Voxel<O>,
count: O,
sign_x: O,
sign_y: O,
sign_z: O,
err_x: I,
err_y: I,
err_z: I,
d_err_x: I,
d_err_y: I,
d_err_z: I
}
impl<I: FloatNum, O: SignedNum> WalkVoxels<I, O> {
#[inline]
pub fn new(start: Voxel<I>, end: Voxel<I>) -> WalkVoxels<I, O> {
let start_i: Voxel<O> = round(start);
let end_i: Voxel<O> = round(end);
let count = (start_i.0 - end_i.0).abs() +
(start_i.1 - end_i.1).abs() +
(start_i.2 - end_i.2).abs();
let sign_x = compare(end_i.0, start_i.0);
let sign_y = compare(end_i.1, start_i.1);
let sign_z = compare(end_i.2, start_i.2);
let x_plane = start_i.0 + (if end_i.0 > start_i.0 {O::one()} else {O::zero()});
let y_plane = start_i.1 + (if end_i.1 > start_i.1 {O::one()} else {O::zero()});
let z_plane = start_i.2 + (if end_i.2 > start_i.2 {O::one()} else {O::zero()});
let vx = if start.0 == end.0 {I::one()} else {end.0 - start.0};
let vy = if start.1 == end.1 {I::one()} else {end.1 - start.1};
let vz = if start.2 == end.2 {I::one()} else {end.2 - start.2};
let vxvy = vx * vy;
let vxvz = vx * vz;
let vyvz = vy * vz;
WalkVoxels {
sign_x, sign_y, sign_z, count,
voxel: start_i,
err_x: (I::cast(x_plane) - start.0) * vyvz,
err_y: (I::cast(y_plane) - start.1) * vxvz,
err_z: (I::cast(z_plane) - start.2) * vxvy,
d_err_x: I::cast(sign_x) * vyvz,
d_err_y: I::cast(sign_y) * vxvz,
d_err_z: I::cast(sign_z) * vxvy
}
}
}
impl<I: FloatNum, O: SignedNum> Iterator for WalkVoxels<I, O> {
type Item = Voxel<O>;
#[inline]
fn next(&mut self) -> Option<Self::Item> {
if self.count >= O::zero() {
self.count -= O::one();
let xr = self.err_x.abs();
let yr = self.err_y.abs();
let zr = self.err_z.abs();
let x_zero = self.sign_x == O::zero();
let y_zero = self.sign_y == O::zero();
let z_zero = self.sign_z == O::zero();
let voxel = self.voxel;
if !x_zero && (y_zero || xr < yr) && (z_zero || xr < zr) {
self.voxel.0 += self.sign_x;
self.err_x += self.d_err_x;
}
else if !y_zero && (z_zero || yr < zr) {
self.voxel.1 += self.sign_y;
self.err_y += self.d_err_y;
}
else if !z_zero {
self.voxel.2 += self.sign_z;
self.err_z += self.d_err_z;
}
Some(voxel)
} else {
None
}
}
}
#[inline]
pub fn walk_voxels<I: FloatNum, O: SignedNum>(start: Voxel<I>, end: Voxel<I>) -> Vec<Voxel<O>> {
WalkVoxels::new(start, end).collect()
}
#[inline]
pub fn walk_voxels_sorted<I: FloatNum, O: SignedNum>(start: Voxel<I>, end: Voxel<I>) -> VecDeque<Voxel<O>> {
let (start, end, reordered) = sort_voxels(start, end);
collect_vec_deque(WalkVoxels::new(start, end), reordered)
}
#[test]
fn tests() {
assert_eq!(
walk_voxels(
(0.472, -1.100, 0.179),
(1.114, -0.391, 0.927)
),
[(0, -1, 0), (1, -1, 0), (1, -1, 1), (1, 0, 1)]
);
}