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

#![deny(missing_docs)]

/*!
This crate contains a capsule collider, which implements the collide trait from the `collide` crate.
**/

use collide::{Collider, CollisionInfo};
use num_traits::{real::Real, One, Zero};
use vector_space::{InnerSpace, VectorSpace};

trait ClampedVector: InnerSpace {
    fn clamped_project(self, dis: Self) -> Self {
        let mag = dis.magnitude();
        let dir = dis / mag;
        let new_mag = self.scalar(dir);
        if new_mag <= Self::Scalar::zero() {
            Self::zero()
        } else if new_mag >= mag {
            dis
        } else {
            dir * new_mag
        }
    }
}

impl<V: InnerSpace> ClampedVector for V {}

#[derive(Copy, Clone)]
/// The capsule collider defined as a convex hull around two spheres having the same radius.
pub struct Capsule<V: VectorSpace> {
    /// The position of one sphere.
    pub start: V,
    /// The position of the other sphere.
    pub end: V,
    /// The radius of the spheres.
    pub rad: V::Scalar,
}

impl<V: InnerSpace> Capsule<V> {
    /// Creates a new capsule collider.
    pub fn new(rad: V::Scalar, start: V, end: V) -> Self {
        Self { start, end, rad }
    }

    /// Creates a new capsule collider representing a point.
    pub fn point(pos: V) -> Self {
        Self {
            start: pos,
            end: pos,
            rad: V::Scalar::zero(),
        }
    }

    /// Creates a new capsule collider representing a line.
    pub fn line(start: V, end: V) -> Self {
        Self {
            start,
            end,
            rad: V::Scalar::zero(),
        }
    }

    /// Creates a new capsule collider representing a sphere.
    pub fn sphere(pos: V, rad: V::Scalar) -> Self {
        Self {
            start: pos,
            end: pos,
            rad,
        }
    }

    fn points(&self, other: &Self) -> (V, V) {
        let p = self.end - self.start;
        let q = other.end - other.start;
        let d = self.start - other.start;

        match (p.is_zero(), q.is_zero()) {
            (false, false) => {
                let p_mag2 = p.magnitude2();
                let q_mag2 = q.magnitude2();
                let angle = p.scalar(q);

                let div = angle * angle - p_mag2 * q_mag2;
                if div.is_zero() {
                    let add = d.reject(p);
                    (self.start, self.start - add)
                } else {
                    let a = (p * q_mag2 - q * angle).scalar(d) / div;
                    let b = (p * angle - q * p_mag2).scalar(d) / div;

                    let zero = V::Scalar::zero();
                    let one = V::Scalar::one();

                    let a_neg = a < zero;
                    let b_neg = b < zero;

                    let a_centered = !a_neg && a <= one;
                    let b_centered = !b_neg && b <= one;

                    if a_centered && b_centered {
                        (self.start + p * a, other.start + q * b)
                    } else {
                        if !a_centered {
                            let a = if a_neg { zero } else { one };
                            let b = (angle * a + q.scalar(d)) / q_mag2;
                            if zero <= b && b <= one {
                                return (self.start + p * a, other.start + q * b);
                            }
                        }
                        if !b_centered {
                            let b = if b_neg { zero } else { one };
                            let a = (angle * b - p.scalar(d)) / p_mag2;
                            if zero <= a && a <= one {
                                return (self.start + p * a, other.start + q * b);
                            }
                        }
                        (
                            if a_neg { self.start } else { self.end },
                            if b_neg { other.start } else { other.end },
                        )
                    }
                }
            }

            (false, true) => (self.start + (-d).clamped_project(p), other.start),
            (true, false) => (self.start, other.start + d.clamped_project(q)),
            (true, true) => (self.start, other.start),
        }
    }
}

impl<V: InnerSpace> Collider for Capsule<V> {
    type Vector = V;

    fn collision_info(&self, other: &Self) -> Option<CollisionInfo<Self::Vector>> {
        let (point, other_point) = self.points(other);

        let dis = other_point - point;
        let mag2 = dis.magnitude2();
        let rad = self.rad + other.rad;
        if mag2 <= rad * rad {
            let mag = mag2.sqrt();
            let dir = dis / mag;
            Some(CollisionInfo {
                self_contact: point + dir * self.rad,
                other_contact: other_point - dir * other.rad,
                vector: dir * (mag - rad),
            })
        } else {
            None
        }
    }
}