shape_core/elements/triangles/
mod.rs

1mod convert;
2mod display;
3mod indexes;
4
5use super::*;
6
7/// A triangles is a polygon with three edges and three vertices. It is one of the basic shapes in geometry.
8///
9/// # Arguments
10///
11/// * `a`:
12/// * `b`:
13/// * `c`:
14///
15/// returns: Triangle<T>
16///
17/// # Examples
18///
19/// ```
20/// # use shape_core::Triangle;
21/// ```
22#[derive(Debug, Clone)]
23pub struct Triangle<T> {
24    /// The 1st vertex of the triangle.
25    pub a: Point<T>,
26    /// The 2nd vertex of the triangle.
27    pub b: Point<T>,
28    /// The 3rd vertex of the triangle.
29    pub c: Point<T>,
30}
31
32/// Clockwise means the front side, and counterclockwise means the back side. When rendering, only the front side is rendered by default, and the back side is invisible.
33///
34/// If you need double-sided display, you need to draw the reverse side at the same time, you can call !self to get the reverse side
35#[derive(Copy, Clone)]
36pub struct TriangleIndex {
37    /// The 1st vertex in the triangle index.
38    pub a: usize,
39    /// The 2nd vertex in the triangle index.
40    pub b: usize,
41    /// The 3rd vertex in the triangle index.
42    pub c: usize,
43}
44
45impl<T> Triangle<T> {
46    /// Create a new triangle from three points.
47    pub fn new<P>(a: P, b: P, c: P) -> Self
48    where
49        P: Into<Point<T>>,
50    {
51        Self { a: a.into(), b: b.into(), c: c.into() }
52    }
53    /// Create a triangle from a mesh and a triangles index.
54    pub fn from_mesh(vertexes: &[Point<T>], index: TriangleIndex) -> Self
55    where
56        T: Clone,
57    {
58        debug_assert!(index.max() < vertexes.len(), "triangles index {index} out of range, must less than {}", vertexes.len());
59        // SAFETY: the debug_assert! above ensures that the index is in range
60        unsafe {
61            Self {
62                a: vertexes.get_unchecked(index.a).clone(),
63                b: vertexes.get_unchecked(index.b).clone(),
64                c: vertexes.get_unchecked(index.c).clone(),
65            }
66        }
67    }
68}
69
70impl<T> Triangle<T>
71where
72    T: Clone + AddAssign + Real,
73{
74    /// Returns true if the triangle is equilateral.
75    pub fn is_congruent(&self) -> bool {
76        true
77    }
78    /// Returns true if the triangle is equilateral.
79    pub fn is_isosceles(&self) -> bool {
80        true
81    }
82
83    /// Returns the perimeter of the triangle.
84    pub fn perimeter(&self) -> T {
85        let mut out = T::zero();
86        for edge in self.edges(3) {
87            out += edge.length();
88        }
89        out
90    }
91
92    /// Returns the area of the triangles.
93    pub fn area(&self) -> T {
94        // Det[{{x0, y0, 1}, {x1, y1, 1}, {x2, y2, 1}}] / 2
95        // x0 y1 - x1 y0
96        let det1 = self.a.x.clone() * self.b.y.clone() - self.b.x.clone() * self.a.y.clone();
97        // x1 y2 - x2 y1
98        let det2 = self.b.x.clone() * self.c.y.clone() - self.c.x.clone() * self.b.y.clone();
99        // x2 y0 - x0 y2
100        let det3 = self.c.x.clone() * self.a.y.clone() - self.a.x.clone() * self.c.y.clone();
101        (det1 + det2 + det3) / two()
102    }
103    /// Get the inscribed circle of the triangles
104    pub fn inscribed_circle(&self) -> Circle<T> {
105        todo!()
106    }
107    /// Get the circumscribed circle of the triangles.
108    pub fn circumscribed_circle(&self) -> Circle<T> {
109        Circle::from_3_points(&self.a, &self.b, &self.c)
110    }
111}
shape_core/elements/triangles/mod.rs

shape_core/elements/triangles/
mod.rs
