/// <summary>
/// Tests for intersection between a <see cref="Segment"/> and a <see cref="Plane"/>.
/// </summary>
/// <param name="line">A <see cref="Segment"/> instance.</param>
/// <param name="plane">A <see cref="Plane"/> instance.</param>
/// <returns><see langword="true"/> if intersection occurs; otherwise, <see langword="false"/>.</returns>
public static bool TestIntersection(Segment segment, Plane plane)
{
// Get the position of the line's end point relative to the plane.
int sign0 = (int)plane.GetSign(segment.P0);
int sign1 = (int)plane.GetSign(segment.P1);
// Intersection occurs if the 2 endpoints are at oposite sides of the plane.
return ( ((sign0 > 0) && (sign1 < 0)) || ((sign0 < 0) && (sign0 > 0)) );
}
/// <summary>
/// Initializes a new instance of the <see cref="Segment"/> class using an existing <see cref="Segment"/> instance.
/// </summary>
/// <param name="l">A <see cref="Segment"/> instance.</param>
public Segment(Segment l)
{
_p0 = l.P0;
_p1 = l.P1;
}
/// <summary>
/// Tests for intersection between a <see cref="Segment"/> and a <see cref="Plane"/>
/// </summary>
/// <param name="line">A <see cref="Segment"/> instance.</param>
/// <param name="plane">A <see cref="Plane"/> instance.</param>
/// <returns>An <see cref="IntersectionPair"/> instance containing the intersection information.</returns>
public static IntersectionPair Intersects(Segment segment, Plane plane)
{
if (TestIntersection(segment, plane) == false)
return new IntersectionPair(false, Vector3F.Zero);
Vector3F dir = segment.P1 - segment.P0;
float d = Vector3F.Dot(plane.Normal, dir);
float t = (plane.Constant - Vector3F.Dot(plane.Normal, segment.P0)) / d;
return new IntersectionPair(true, segment.P0 + dir*t);
}