use super::{ParametricShape, Shape};
#[derive(Clone)]
pub struct Torus {
pub center: (f64, f64, f64),
pub major_radius: f64,
pub minor_radius: f64,
pub axis: (f64, f64, f64),
axis_len: f64,
}
impl Torus {
pub fn new(
center: (f64, f64, f64),
major_radius: f64,
minor_radius: f64,
axis: (f64, f64, f64),
) -> Self {
let axis_len = (axis.0 * axis.0 + axis.1 * axis.1 + axis.2 * axis.2).sqrt();
Self {
center,
major_radius,
minor_radius,
axis,
axis_len,
}
}
fn normalized_axis(&self) -> (f64, f64, f64) {
if self.axis_len == 0.0 {
(0.0, 1.0, 0.0)
} else {
(
self.axis.0 / self.axis_len,
self.axis.1 / self.axis_len,
self.axis.2 / self.axis_len,
)
}
}
fn local_coords(&self, x: i32, y: i32, z: i32) -> (f64, f64, f64) {
let ax = self.normalized_axis();
let dx = x as f64 - self.center.0;
let dy = y as f64 - self.center.1;
let dz = z as f64 - self.center.2;
let h = dx * ax.0 + dy * ax.1 + dz * ax.2;
let px = dx - h * ax.0;
let py = dy - h * ax.1;
let pz = dz - h * ax.2;
let planar_dist = (px * px + py * py + pz * pz).sqrt();
(planar_dist, h, planar_dist.atan2(1.0))
}
}
impl Shape for Torus {
fn contains(&self, x: i32, y: i32, z: i32) -> bool {
let (planar_dist, h, _) = self.local_coords(x, y, z);
let d = planar_dist - self.major_radius;
d * d + h * h <= self.minor_radius * self.minor_radius
}
fn points(&self) -> Vec<(i32, i32, i32)> {
let mut points = Vec::new();
self.for_each_point(|x, y, z| points.push((x, y, z)));
points
}
fn normal_at(&self, x: i32, y: i32, z: i32) -> (f64, f64, f64) {
let ax = self.normalized_axis();
let dx = x as f64 - self.center.0;
let dy = y as f64 - self.center.1;
let dz = z as f64 - self.center.2;
let h = dx * ax.0 + dy * ax.1 + dz * ax.2;
let px = dx - h * ax.0;
let py = dy - h * ax.1;
let pz = dz - h * ax.2;
let planar_dist = (px * px + py * py + pz * pz).sqrt();
if planar_dist == 0.0 {
return (0.0, 1.0, 0.0);
}
let tube_center_x = px / planar_dist * self.major_radius;
let tube_center_y = py / planar_dist * self.major_radius;
let tube_center_z = pz / planar_dist * self.major_radius;
let nx = dx - tube_center_x;
let ny = dy - tube_center_y;
let nz = dz - tube_center_z;
let len = (nx * nx + ny * ny + nz * nz).sqrt();
if len == 0.0 {
(0.0, 1.0, 0.0)
} else {
(nx / len, ny / len, nz / len)
}
}
fn bounds(&self) -> (i32, i32, i32, i32, i32, i32) {
let total = self.major_radius + self.minor_radius;
let r = total.ceil() as i32 + 1;
let cx = self.center.0.round() as i32;
let cy = self.center.1.round() as i32;
let cz = self.center.2.round() as i32;
(cx - r, cy - r, cz - r, cx + r, cy + r, cz + r)
}
fn for_each_point<F>(&self, mut f: F)
where
F: FnMut(i32, i32, i32),
{
let (min_x, min_y, min_z, max_x, max_y, max_z) = self.bounds();
for x in min_x..=max_x {
for y in min_y..=max_y {
for z in min_z..=max_z {
if self.contains(x, y, z) {
f(x, y, z);
}
}
}
}
}
}
impl ParametricShape for Torus {
fn parameter_at(&self, x: i32, y: i32, z: i32) -> f64 {
let ax = self.normalized_axis();
let dx = x as f64 - self.center.0;
let dy = y as f64 - self.center.1;
let dz = z as f64 - self.center.2;
let h = dx * ax.0 + dy * ax.1 + dz * ax.2;
let px = dx - h * ax.0;
let py = dy - h * ax.1;
let angle = py.atan2(px); ((angle + std::f64::consts::PI) / (2.0 * std::f64::consts::PI)).clamp(0.0, 1.0)
}
}