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|
use glam::{IVec2, Vec2};
// Amanatide's and Woo's fast Voxel Traversal
pub struct AwDda {
next: IVec2,
step_sign: IVec2,
step_delta: Vec2,
t_max: Vec2,
done: bool,
}
impl AwDda {
pub fn new(from: Vec2, to: Vec2) -> Self {
let first = from.round().as_ivec2();
// direction we step for each component on each iteration
let from_to_delta = to - from;
let step_sign = from_to_delta.signum().as_ivec2();
let step_delta = 1.0 / from_to_delta.abs();
let frac = Vec2::new(
if step_sign.x > 0 {
(first.x as f32 + 0.5) - from.x
} else {
from.x - (first.x as f32 - 0.5)
},
if step_sign.y > 0 {
(first.y as f32 + 0.5) - from.y
} else {
from.y - (first.y as f32 - 0.5)
},
);
let t_max = frac * step_delta;
AwDda {
next: first,
step_sign,
step_delta,
t_max,
done: false,
}
}
}
impl Iterator for AwDda {
type Item = IVec2;
fn next(&mut self) -> Option<Self::Item> {
if self.done {
return None;
}
if self.t_max.min_element() >= 1.0 {
self.done = true;
return Some(self.next);
}
let cur = self.next;
if self.t_max.x < self.t_max.y {
self.next.x += self.step_sign.x;
self.t_max.x += self.step_delta.x;
} else {
self.next.y += self.step_sign.y;
self.t_max.y += self.step_delta.y;
}
Some(cur)
}
}
|
