symtropy_math/
point.rs

1// Copyright (C) 2024-2026 Tristan Stoltz / Luminous Dynamics
2// SPDX-License-Identifier: AGPL-3.0-or-later
3// Commercial licensing: see COMMERCIAL_LICENSE.md at repository root
4use nalgebra::SVector;
5use std::ops::{Add, Sub};
6
7/// A point in D-dimensional space. Stack-allocated via nalgebra::SVector.
8#[derive(Clone, Copy, Debug, PartialEq)]
9pub struct Point<const D: usize>(pub SVector<f64, D>);
10
11impl<const D: usize> Point<D> {
12    /// Point at the origin.
13    pub fn origin() -> Self {
14        Self(SVector::zeros())
15    }
16
17    /// Create from a fixed-size array.
18    pub fn new(coords: [f64; D]) -> Self {
19        Self(SVector::from(coords))
20    }
21
22    /// Euclidean distance to another point.
23    #[inline]
24    pub fn distance(&self, other: &Self) -> f64 {
25        (self.0 - other.0).norm()
26    }
27
28    /// Squared distance (avoids sqrt — use for comparisons).
29    #[inline]
30    pub fn distance_squared(&self, other: &Self) -> f64 {
31        (self.0 - other.0).norm_squared()
32    }
33
34    /// Linear interpolation: self*(1-t) + other*t.
35    #[inline]
36    pub fn lerp(&self, other: &Self, t: f64) -> Self {
37        Self(self.0 * (1.0 - t) + other.0 * t)
38    }
39
40    /// Access coordinate by index.
41    #[inline]
42    pub fn coord(&self, i: usize) -> f64 {
43        self.0[i]
44    }
45
46    /// Mutable coordinate access.
47    #[inline]
48    pub fn coord_mut(&mut self, i: usize) -> &mut f64 {
49        &mut self.0[i]
50    }
51
52    /// Convert to direction vector.
53    #[inline]
54    pub fn to_vector(&self) -> SVector<f64, D> {
55        self.0
56    }
57}
58
59impl<const D: usize> Add<SVector<f64, D>> for Point<D> {
60    type Output = Point<D>;
61    #[inline]
62    fn add(self, rhs: SVector<f64, D>) -> Point<D> {
63        Point(self.0 + rhs)
64    }
65}
66
67impl<const D: usize> Sub for Point<D> {
68    type Output = SVector<f64, D>;
69    #[inline]
70    fn sub(self, rhs: Point<D>) -> SVector<f64, D> {
71        self.0 - rhs.0
72    }
73}
74
75impl<const D: usize> Default for Point<D> {
76    fn default() -> Self {
77        Self::origin()
78    }
79}
80
81#[cfg(test)]
82mod tests {
83    use super::*;
84
85    #[test]
86    fn origin_is_zero() {
87        let p = Point::<4>::origin();
88        for i in 0..4 {
89            assert_eq!(p.coord(i), 0.0);
90        }
91    }
92
93    #[test]
94    fn distance_2d() {
95        let a = Point::new([0.0, 0.0]);
96        let b = Point::new([3.0, 4.0]);
97        assert!((a.distance(&b) - 5.0).abs() < 1e-12);
98    }
99
100    #[test]
101    fn distance_4d() {
102        let a = Point::new([1.0, 2.0, 3.0, 4.0]);
103        let b = Point::new([5.0, 6.0, 7.0, 8.0]);
104        assert!((a.distance(&b) - 8.0).abs() < 1e-12);
105    }
106
107    #[test]
108    fn lerp_midpoint() {
109        let a = Point::new([0.0, 0.0, 0.0]);
110        let b = Point::new([10.0, 20.0, 30.0]);
111        let mid = a.lerp(&b, 0.5);
112        assert!((mid.coord(0) - 5.0).abs() < 1e-12);
113        assert!((mid.coord(1) - 10.0).abs() < 1e-12);
114    }
115
116    #[test]
117    fn subtraction() {
118        let a = Point::new([1.0, 2.0]);
119        let b = Point::new([4.0, 6.0]);
120        let v = b - a;
121        assert!((v[0] - 3.0).abs() < 1e-12);
122        assert!((v[1] - 4.0).abs() < 1e-12);
123    }
124
125    #[test]
126    fn is_copy() {
127        let a = Point::new([1.0, 2.0]);
128        let b = a;
129        assert_eq!(a, b);
130    }
131}
symtropy_math/point.rs

symtropy_math/
point.rs
