1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124

use std::fmt;

use fj_math::{Circle, Line, Point, Vector};

/// A one-dimensional shape
///
/// The word "curve" is used as an umbrella term for all one-dimensional shapes,
/// and doesn't imply that those shapes need to be curved. Straight lines are
/// included.
///
/// The nomenclature is inspired by Boundary Representation Modelling Techniques
/// by Ian Stroud. "Curve" refers to unbounded one-dimensional geometry, while
/// while edges are bounded portions of curves.
///
/// The `D` parameter defines the dimensions in which the curve is defined.
/// Typically, only `2` or `3` make sense, which means the curve is defined on
/// a surface or in a space, respectively.
#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash, Ord, PartialOrd)]
pub enum Curve<const D: usize> {
    /// A circle
    Circle(Circle<D>),

    /// A line
    Line(Line<D>),
}

impl<const D: usize> Curve<D> {
    /// Construct a line from two points
    pub fn line_from_points(points: [impl Into<Point<D>>; 2]) -> Self {
        Self::Line(Line::from_points(points))
    }

    /// Access the origin of the curve's coordinate system
    pub fn origin(&self) -> Point<D> {
        match self {
            Self::Circle(curve) => curve.center,
            Self::Line(curve) => curve.origin,
        }
    }

    /// Create a new instance that is reversed
    #[must_use]
    pub fn reverse(self) -> Self {
        match self {
            Self::Circle(curve) => Self::Circle(curve.reverse()),
            Self::Line(curve) => Self::Line(curve.reverse()),
        }
    }

    /// Convert a point on the curve into model coordinates
    pub fn point_from_curve_coords(
        &self,
        point: impl Into<Point<1>>,
    ) -> Point<D> {
        match self {
            Self::Circle(curve) => curve.point_from_circle_coords(point),
            Self::Line(curve) => curve.point_from_line_coords(point),
        }
    }

    /// Convert a vector on the curve into model coordinates
    pub fn vector_from_curve_coords(
        &self,
        point: impl Into<Vector<1>>,
    ) -> Vector<D> {
        match self {
            Self::Circle(curve) => curve.vector_from_circle_coords(point),
            Self::Line(curve) => curve.vector_from_line_coords(point),
        }
    }
}

impl Curve<2> {
    /// Construct a `Curve` that represents the u-axis
    pub fn u_axis() -> Self {
        Self::Line(Line {
            origin: Point::origin(),
            direction: Vector::unit_u(),
        })
    }

    /// Construct a `Curve` that represents the v-axis
    pub fn v_axis() -> Self {
        Self::Line(Line {
            origin: Point::origin(),
            direction: Vector::unit_v(),
        })
    }
}

impl Curve<3> {
    /// Construct a `Curve` that represents the x-axis
    pub fn x_axis() -> Self {
        Self::Line(Line {
            origin: Point::origin(),
            direction: Vector::unit_x(),
        })
    }

    /// Construct a `Curve` that represents the y-axis
    pub fn y_axis() -> Self {
        Self::Line(Line {
            origin: Point::origin(),
            direction: Vector::unit_y(),
        })
    }

    /// Construct a `Curve` that represents the z-axis
    pub fn z_axis() -> Self {
        Self::Line(Line {
            origin: Point::origin(),
            direction: Vector::unit_z(),
        })
    }
}

impl<const D: usize> fmt::Display for Curve<D> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            Self::Circle(curve) => write!(f, "{:?}", curve),
            Self::Line(curve) => write!(f, "{:?}", curve),
        }
    }
}