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

use crate::math::{Isometry, Point, Real, Vector};
use crate::query::{self, ContactManifold, TrackedContact};
use crate::shape::Segment;

/// A polygonal feature representing the local polygonal approximation of
/// a vertex, or face, of a convex shape.
#[derive(Debug)]
pub struct PolygonalFeature {
    /// Up to two vertices forming this polygonal feature.
    pub vertices: [Point<Real>; 2],
    /// The feature IDs of this polygon's vertices.
    pub vids: [u32; 2],
    /// The feature ID of this polygonal feature.
    pub fid: u32,
    /// The number of vertices on this polygon (must be <= 4).
    pub num_vertices: usize,
}

impl Default for PolygonalFeature {
    fn default() -> Self {
        Self {
            vertices: [Point::origin(); 2],
            vids: [0; 2],
            fid: 0,
            num_vertices: 0,
        }
    }
}

impl From<Segment> for PolygonalFeature {
    fn from(seg: Segment) -> Self {
        PolygonalFeature {
            vertices: [seg.a, seg.b],
            vids: [0, 2],
            fid: 1,
            num_vertices: 2,
        }
    }
}

impl PolygonalFeature {
    /// Transforms the vertices of `self` by the given position `pos`.
    pub fn transform_by(&mut self, pos: &Isometry<Real>) {
        self.vertices[0] = pos * self.vertices[0];
        self.vertices[1] = pos * self.vertices[1];
    }

    /// Computes the contacts between two polygonal features.
    pub fn contacts<ManifoldData, ContactData: Default + Copy>(
        pos12: &Isometry<Real>,
        pos21: &Isometry<Real>,
        sep_axis1: &Vector<Real>,
        sep_axis2: &Vector<Real>,
        feature1: &Self,
        feature2: &Self,
        prediction: Real,
        manifold: &mut ContactManifold<ManifoldData, ContactData>,
        flipped: bool,
    ) {
        match (feature1.num_vertices == 2, feature2.num_vertices == 2) {
            (true, true) => Self::face_face_contacts(
                pos12, feature1, sep_axis1, feature2, prediction, manifold, flipped,
            ),
            (true, false) => Self::face_vertex_contacts(
                pos12, feature1, sep_axis1, feature2, prediction, manifold, flipped,
            ),
            (false, true) => Self::face_vertex_contacts(
                pos21, feature2, sep_axis2, feature1, prediction, manifold, !flipped,
            ),
            (false, false) => unimplemented!(),
        }
    }

    /// Compute contacts points between a face and a vertex.
    ///
    /// This method assume we already know that at least one contact exists.
    pub fn face_vertex_contacts<ManifoldData, ContactData: Default + Copy>(
        pos12: &Isometry<Real>,
        face1: &Self,
        sep_axis1: &Vector<Real>,
        vertex2: &Self,
        _prediction: Real,
        manifold: &mut ContactManifold<ManifoldData, ContactData>,
        flipped: bool,
    ) {
        let v2_1 = pos12 * vertex2.vertices[0];
        let tangent1 = face1.vertices[1] - face1.vertices[0];
        let normal1 = Vector::new(-tangent1.y, tangent1.x);
        let denom = -normal1.dot(&sep_axis1);
        let dist = (face1.vertices[0] - v2_1).dot(&normal1) / denom;
        let local_p2 = v2_1;
        let local_p1 = v2_1 - dist * normal1;

        let contact = TrackedContact::flipped(
            local_p1,
            pos12.inverse_transform_point(&local_p2),
            face1.fid,
            vertex2.vids[0],
            dist,
            flipped,
        );

        manifold.points.push(contact);
    }

    /// Computes the contacts between two polygonal faces.
    pub fn face_face_contacts<ManifoldData, ContactData: Default + Copy>(
        pos12: &Isometry<Real>,
        face1: &Self,
        normal1: &Vector<Real>,
        face2: &Self,
        _prediction: Real,
        manifold: &mut ContactManifold<ManifoldData, ContactData>,
        flipped: bool,
    ) {
        if let Some((clip_a, clip_b)) = query::details::clip_segment_segment_with_normal(
            (face1.vertices[0], face1.vertices[1]),
            (pos12 * face2.vertices[0], pos12 * face2.vertices[1]),
            *normal1,
        ) {
            let fids1 = [face1.vids[0], face1.fid, face1.vids[1]];
            let fids2 = [face2.vids[0], face2.fid, face2.vids[1]];

            let dist = (clip_a.1 - clip_a.0).dot(normal1);
            if true {
                // dist < prediction {
                let contact = TrackedContact::flipped(
                    clip_a.0,
                    pos12.inverse_transform_point(&clip_a.1),
                    fids1[clip_a.2],
                    fids2[clip_a.3],
                    dist,
                    flipped,
                );
                manifold.points.push(contact);
            }

            let dist = (clip_b.1 - clip_b.0).dot(normal1);
            if true {
                // dist < prediction {
                let contact = TrackedContact::flipped(
                    clip_b.0,
                    pos12.inverse_transform_point(&clip_b.1),
                    fids1[clip_b.2],
                    fids2[clip_b.3],
                    dist,
                    flipped,
                );
                manifold.points.push(contact);
            }
        }
    }
}