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
176
177
178
179
180
181
182
183
184
185

use crate::math::{Isometry, Real, Vector};
use crate::query::{ContactManifold, TrackedContact};
#[cfg(feature = "dim2")]
use crate::shape::SegmentPointLocation;
use crate::shape::{Capsule, PackedFeatureId, Shape};
use approx::AbsDiffEq;
use na::Unit;

#[cfg(not(feature = "std"))]
use na::ComplexField; // for .abs()

/// Computes the contact manifold between two capsules given as `Shape` trait-objects.
pub fn contact_manifold_capsule_capsule_shapes<ManifoldData, ContactData>(
    pos12: &Isometry<Real>,
    shape1: &dyn Shape,
    shape2: &dyn Shape,
    prediction: Real,
    manifold: &mut ContactManifold<ManifoldData, ContactData>,
) where
    ContactData: Default + Copy,
{
    if let (Some(capsule1), Some(capsule2)) = (shape1.as_capsule(), shape2.as_capsule()) {
        contact_manifold_capsule_capsule(pos12, capsule1, capsule2, prediction, manifold);
    }
}

/// Computes the contact manifold between two capsules.
#[cfg(feature = "dim2")]
pub fn contact_manifold_capsule_capsule<'a, ManifoldData, ContactData>(
    pos12: &Isometry<Real>,
    capsule1: &'a Capsule,
    capsule2: &'a Capsule,
    prediction: Real,
    manifold: &mut ContactManifold<ManifoldData, ContactData>,
) where
    ContactData: Default + Copy,
{
    let seg1 = capsule1.segment;
    let seg2_1 = capsule2.segment.transformed(pos12);
    let (loc1, loc2) = crate::query::details::closest_points_segment_segment_with_locations_nD(
        (&seg1.a, &seg1.b),
        (&seg2_1.a, &seg2_1.b),
    );

    // We do this clone to perform contact tracking and transfer impulses.
    // TODO: find a more efficient way of doing this.
    let old_manifold_points = manifold.points.clone();
    manifold.clear();

    let fid1 = if let SegmentPointLocation::OnVertex(v1) = loc1 {
        v1 * 2
    } else {
        1
    };
    let fid2 = if let SegmentPointLocation::OnVertex(v2) = loc2 {
        v2 * 2
    } else {
        1
    };

    let bcoords1 = loc1.barycentric_coordinates();
    let bcoords2 = loc2.barycentric_coordinates();
    let local_p1 = seg1.a * bcoords1[0] + seg1.b.coords * bcoords1[1];
    let local_p2_1 = seg2_1.a * bcoords2[0] + seg2_1.b.coords * bcoords2[1];

    let local_n1 =
        Unit::try_new(local_p2_1 - local_p1, Real::default_epsilon()).unwrap_or(Vector::y_axis());
    let dist = (local_p2_1 - local_p1).dot(&local_n1);

    if dist <= prediction + capsule1.radius + capsule2.radius {
        let local_n2 = pos12.inverse_transform_unit_vector(&-local_n1);
        let local_p2 = pos12.inverse_transform_point(&local_p2_1);
        let contact = TrackedContact::new(
            local_p1,
            local_p2,
            PackedFeatureId::face(fid1),
            PackedFeatureId::face(fid2),
            dist,
        );
        manifold.points.push(contact);

        manifold.local_n1 = *local_n1;
        manifold.local_n2 = *local_n2;
    } else {
        // No contact within tolerance.
        return;
    }

    if let (Some(dir1), Some(dir2)) = (seg1.direction(), seg2_1.direction()) {
        if dir1.dot(&dir2).abs() >= crate::utils::COS_FRAC_PI_8
            && dir1.dot(&local_n1).abs() < crate::utils::SIN_FRAC_PI_8
        {
            // Capsules axes are almost parallel and are almost perpendicular to the normal.
            // Find a second contact point.
            if let Some((clip_a, clip_b)) = crate::query::details::clip_segment_segment_with_normal(
                (seg1.a, seg1.b),
                (seg2_1.a, seg2_1.b),
                *local_n1,
            ) {
                let contact =
                    if (clip_a.0 - local_p1).norm_squared() > Real::default_epsilon() * 100.0 {
                        // Use clip_a as the second contact.
                        TrackedContact::new(
                            clip_a.0,
                            pos12.inverse_transform_point(&clip_a.1),
                            PackedFeatureId::face(clip_a.2 as u32),
                            PackedFeatureId::face(clip_a.3 as u32),
                            (clip_a.1 - clip_a.0).dot(&local_n1),
                        )
                    } else {
                        // Use clip_b as the second contact.
                        TrackedContact::new(
                            clip_b.0,
                            pos12.inverse_transform_point(&clip_b.1),
                            PackedFeatureId::face(clip_b.2 as u32),
                            PackedFeatureId::face(clip_b.3 as u32),
                            (clip_b.1 - clip_b.0).dot(&local_n1),
                        )
                    };

                manifold.points.push(contact);
            }
        }
    }

    for point in &mut manifold.points {
        point.local_p1 += manifold.local_n1 * capsule1.radius;
        point.local_p2 += manifold.local_n2 * capsule2.radius;
        point.dist -= capsule1.radius + capsule2.radius;
    }

    manifold.match_contacts(&old_manifold_points);
}

/// Computes the contact manifold between two capsules.
#[cfg(feature = "dim3")]
pub fn contact_manifold_capsule_capsule<'a, ManifoldData, ContactData>(
    pos12: &Isometry<Real>,
    capsule1: &'a Capsule,
    capsule2: &'a Capsule,
    prediction: Real,
    manifold: &mut ContactManifold<ManifoldData, ContactData>,
) where
    ContactData: Default + Copy,
{
    let seg1 = capsule1.segment;
    let seg2_1 = capsule2.segment.transformed(pos12);
    let (loc1, loc2) =
        crate::query::closest_points::closest_points_segment_segment_with_locations_nD(
            (&seg1.a, &seg1.b),
            (&seg2_1.a, &seg2_1.b),
        );

    let bcoords1 = loc1.barycentric_coordinates();
    let bcoords2 = loc2.barycentric_coordinates();
    let local_p1 = seg1.a * bcoords1[0] + seg1.b.coords * bcoords1[1];
    let local_p2_1 = seg2_1.a * bcoords2[0] + seg2_1.b.coords * bcoords2[1];

    let local_n1 =
        Unit::try_new(local_p2_1 - local_p1, Real::default_epsilon()).unwrap_or(Vector::y_axis());
    let dist = (local_p2_1 - local_p1).dot(&local_n1) - capsule1.radius - capsule2.radius;

    if dist <= prediction {
        let local_n2 = pos12.inverse_transform_unit_vector(&-local_n1);
        let fid = PackedFeatureId::face(0);
        let contact = TrackedContact::new(
            local_p1 + *local_n1 * capsule1.radius,
            pos12.inverse_transform_point(&local_p2_1) + *local_n2 * capsule2.radius,
            fid,
            fid,
            dist,
        );

        if !manifold.points.is_empty() {
            manifold.points[0].copy_geometry_from(contact);
        } else {
            manifold.points.push(contact);
        }

        manifold.local_n1 = *local_n1;
        manifold.local_n2 = *local_n2;
    } else {
        manifold.clear();
    }
}