// Polygon versus 2-sided edge.
public static void CollidePolyAndEdge(ref Manifold manifold, PolygonShape polygon, XForm transformA, EdgeShape edge, XForm transformB)
{
PolygonShape polygonB = new PolygonShape();
polygonB.SetAsEdge(edge._v1, edge._v2);
CollidePolygons(ref manifold, polygon, transformA, polygonB, transformB);
}
public void SetNextEdge(EdgeShape edge, Vector2 cornerDir, bool convex)
{
_nextEdge = edge;
_cornerDir2 = cornerDir;
_cornerConvex2 = convex;
}
// This implements 2-sided edge vs circle collision.
public static void CollideEdgeAndCircle(ref Manifold manifold, EdgeShape edge, XForm transformA, CircleShape circle, XForm transformB)
{
manifold.PointCount = 0;
Vec2 cLocal = Common.MathB2.MulT(transformA, Common.MathB2.Mul(transformB, circle._position));
Vec2 normal = edge._normal;
Vec2 v1 = edge._v1;
Vec2 v2 = edge._v2;
float radius = edge._radius + circle._radius;
// Barycentric coordinates
float u1 = Vec2.Dot(cLocal - v1, v2 - v1);
float u2 = Vec2.Dot(cLocal - v2, v1 - v2);
if (u1 <= 0.0f)
{
// Behind v1
if (Vec2.DistanceSquared(cLocal, v1) > radius * radius)
{
return;
}
manifold.PointCount = 1;
manifold.Type = ManifoldType.FaceA;
manifold.LocalPlaneNormal = cLocal - v1;
manifold.LocalPlaneNormal.Normalize();
manifold.LocalPoint = v1;
manifold.Points[0].LocalPoint = circle._position;
manifold.Points[0].ID.Key = 0;
}
else if (u2 <= 0.0f)
{
// Ahead of v2
if (Vec2.DistanceSquared(cLocal, v2) > radius * radius)
{
return;
}
manifold.PointCount = 1;
manifold.Type = ManifoldType.FaceA;
manifold.LocalPlaneNormal = cLocal - v2;
manifold.LocalPlaneNormal.Normalize();
manifold.LocalPoint = v2;
manifold.Points[0].LocalPoint = circle._position;
manifold.Points[0].ID.Key = 0;
}
else
{
float separation = Vec2.Dot(cLocal - v1, normal);
if (separation < -radius || radius < separation)
{
return;
}
manifold.PointCount = 1;
manifold.Type = ManifoldType.FaceA;
manifold.LocalPlaneNormal = separation < 0.0f ? -normal : normal;
manifold.LocalPoint = 0.5f * (v1 + v2);
manifold.Points[0].LocalPoint = circle._position;
manifold.Points[0].ID.Key = 0;
}
}
public void SetPrevEdge(EdgeShape edge, Vector2 cornerDir, bool convex)
{
_prevEdge = edge;
_cornerDir1 = cornerDir;
_cornerConvex1 = convex;
}
