public LineSegmentCircleIntersect(LineSegment segment, Vector3 circleCenter, float circleRadius)
{
Vector3 a = segment.A;
Vector3 b = segment.B;
Vector3 c = circleCenter;
// Compute a normal perpendicular to the line and pointing to the point
Vector3 up = Vector3.Cross(segment.A - circleCenter, segment.A - segment.B); // This points up from the line
Vector3 normal = Vector3.Cross(up, segment.A - segment.B);
float distanceToLine = 0.0f;
if (normal.Length > 0.0f)
{
distanceToLine = Math.Abs(new Plane(normal, segment.A).Distance(circleCenter));
}
if (distanceToLine >= circleRadius)
{
intersectType = IntersectType.None;
return;
}
if (distanceToLine == float.NaN)
{
}
float along = (float)Math.Sqrt(Math.Pow(circleRadius, 2) - Math.Pow(distanceToLine, 2));
Plane plane = new Plane(b - a, a);
float toA = 0.0f;
float toB = plane.Distance(b);
float toC = plane.Distance(c);
float toP1 = toC - along;
float toP2 = toC + along;
if (toP2 < toA || toP1 > toB)
{
intersectType = IntersectType.None;
return;
}
if (toP1 > toA)
{
beginNoIntersect = new LineSegment(a, a + toA * plane.Normal);
}
if (toP2 < toB)
{
endNoIntersect = new LineSegment(a + toP2 * plane.Normal, a + toB * plane.Normal);
}
toP1 = Math.Min(Math.Max(toP1, toA), toB);
toP2 = Math.Min(Math.Max(toP2, toA), toB);
intersectType = IntersectType.Segment;
intersectSegment = new LineSegment(a + plane.Normal * toP1, a + plane.Normal * toP2);
}
/// <summary>
/// Subtract another line segment from this one.
/// It's assumed that the other segment lies on the same line as this one.
/// </summary>
/// <param name="other"></param>
public List<LineSegment> Subtract(LineSegment other)
{
//Vector3 n = b - a;
//n.Normalize();
Plane plane = new Plane(b - a, a);
float toB = plane.Distance(b);
float toOtherA = plane.Distance(other.a);
float toOtherB = plane.Distance(other.b);
if (toOtherA > toOtherB)
{
float temp = toOtherA;
toOtherA = toOtherB;
toOtherB = temp;
}
else
{
}
List<LineSegment> remainingSegments = new List<LineSegment>();
// Check for no overlap
if (toOtherA >= toB || toOtherB <= 0.0f)
{
remainingSegments.Add(new LineSegment(a, b));
return remainingSegments;
}
if (toOtherA > 0)
{
Vector3 p1 = a;
remainingSegments.Add(new LineSegment(a, a + plane.Normal * toOtherA));
}
if (toOtherB < toB)
{
remainingSegments.Add(new LineSegment(a + plane.Normal * toOtherB, b));
}
return remainingSegments;
}