collision2d 0.2.3

A simple 2d collision detection library
Documentation 
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
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175

use core::borrow::Borrow;

use crate::{abs, Collides, Penetration};

/// Axis-Aligned Bounding Box
#[derive(Debug, Copy, Clone, PartialEq)]
pub struct Aabb {
    x: Range,
    y: Range,
}

impl Aabb {
    /// Create from `min` and `max` points
    ///
    /// In a typical screen-space coordinate system (the x-axis points to the right, and the y-axis points down)
    /// `min` would be the "top-left" and `max` would be the "bottom-right"
    #[must_use]
    pub fn from_min_max(min: impl Into<[f32; 2]>, max: impl Into<[f32; 2]>) -> Self {
        let min = min.into();
        let max = max.into();
        let x = Range::from_min_max(min[0], max[0]);
        let y = Range::from_min_max(min[1], max[1]);
        Self { x, y }
    }

    /// Create from `top_left` and `size` of the rectangle
    #[must_use]
    pub fn from_top_left_and_size(
        top_left: impl Into<[f32; 2]>,
        size: impl Into<[f32; 2]>,
    ) -> Self {
        let [x, y] = top_left.into();
        let [w, h] = size.into();
        let x = Range::from_min_max(x, x + w);
        let y = Range::from_min_max(y, y + h);
        Self { x, y }
    }

    /// Move the shape by the given offset
    pub fn offset(&mut self, offset: impl Into<[f32; 2]>) {
        let [dx, dy] = offset.into();
        self.x.offset(dx);
        self.y.offset(dy);
    }

    /// Returned shape after appliying the offset
    #[must_use]
    pub fn with_offset(mut self, offset: impl Into<[f32; 2]>) -> Self {
        self.offset(offset);
        self
    }

    /// Returns the minimum point of the shape
    ///
    /// In a typical screen-space coordinate system (the x-axis points to the right, and the y-axis points down)
    /// this would be the "top-left"
    #[must_use]
    pub fn min(&self) -> [f32; 2] {
        [self.x.min, self.y.min]
    }

    /// Returns the maximum point of the shape
    ///
    /// In a typical screen-space coordinate system (the x-axis points to the right, and the y-axis points down)
    /// this would be the "bottom-right"
    #[must_use]
    pub fn max(&self) -> [f32; 2] {
        [self.x.max, self.y.max]
    }

    /// Returs the size of the shape
    #[must_use]
    pub fn size(&self) -> [f32; 2] {
        [self.x.max - self.x.min, self.y.max - self.y.min]
    }
}

impl Collides for Aabb {
    fn collides(&self, other: impl Borrow<Aabb>) -> bool {
        let other = other.borrow();
        self.x.collides(other.x) && self.y.collides(other.y)
    }
}

impl Penetration for Aabb {
    fn penetration(&self, other: impl Borrow<Self>) -> Option<[f32; 2]> {
        let other = other.borrow();
        let x = self.x.penetration(other.x)?;
        let y = self.y.penetration(other.y)?;
        Some(if abs(x) < abs(y) { [x, 0.] } else { [0., y] })
    }
}

#[derive(Debug, Copy, Clone, PartialEq)]
struct Range {
    min: f32,
    max: f32,
}

impl Range {
    fn from_min_max(min: f32, max: f32) -> Self {
        Self {
            min: min.min(max),
            max: min.max(max),
        }
    }

    fn penetration(self, other: Self) -> Option<f32> {
        let p1 = Some(other.min - self.max).filter(|p| *p < 0.)?;
        let p2 = Some(other.max - self.min).filter(|p| *p > 0.)?;
        Some(if abs(p1) < abs(p2) { p1 } else { p2 })
    }

    fn offset(&mut self, offset: f32) {
        self.min += offset;
        self.max += offset;
    }
}

impl Collides for Range {
    fn collides(&self, other: impl Borrow<Self>) -> bool {
        let other = other.borrow();
        self.max > other.min && self.min < other.max
    }
}

impl From<Range> for [f32; 2] {
    fn from(Range { min, max }: Range) -> Self {
        [min, max]
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn range_should_penetrate_self() {
        let range = Range::from_min_max(0., 1.);
        assert_eq!(range.penetration(range).map(abs), Some(1.0));
    }

    #[test]
    #[allow(clippy::float_cmp)]
    fn can_get_min_max_from_aabb() {
        let aabb = Aabb::from_min_max([1., 2.], [3., 4.]);
        assert_eq!(aabb.min(), [1., 2.]);
        assert_eq!(aabb.max(), [3., 4.]);
    }

    #[test]
    #[allow(clippy::float_cmp)]
    fn can_build_from_top_left_and_size() {
        let from_min_max = Aabb::from_min_max([1., 2.], [3., 5.]);
        let from_rect = Aabb::from_top_left_and_size([1., 2.], [2., 3.]);
        assert_eq!(from_min_max, from_rect);
        assert_eq!(from_rect.size(), [2., 3.]);
        assert_eq!(from_min_max.size(), [2., 3.]);
    }

    #[test]
    fn can_build_from_top_left_and_negative_size() {
        let from_min_max = Aabb::from_min_max([1., 2.], [3., 5.]);
        let from_rect = Aabb::from_top_left_and_size([3., 5.], [-2., -3.]);
        assert_eq!(from_min_max, from_rect);
    }

    #[test]
    #[allow(clippy::float_cmp)]
    fn can_offset_shape() {
        let aabb = Aabb::from_min_max([1., 2.], [3., 4.]).with_offset([5.0, 6.0]);
        assert_eq!(aabb.min(), [6., 8.]);
        assert_eq!(aabb.max(), [8., 10.]);
    }
}