這裏是我最終使用:
public static List<Point3D> IntersectionOfLineSegmentWithAxisAlignedBox(
Point3D segmentBegin, Point3D segmentEnd, Point3D boxCenter, Size3D boxSize)
{
var beginToEnd = segmentEnd - segmentBegin;
var minToMax = new Vector3D(boxSize.X, boxSize.Y, boxSize.Z);
var min = boxCenter - minToMax/2;
var max = boxCenter + minToMax/2;
var beginToMin = min - segmentBegin;
var beginToMax = max - segmentBegin;
var tNear = double.MinValue;
var tFar = double.MaxValue;
var intersections = new List<Point3D>();
foreach (Axis axis in Enum.GetValues(typeof(Axis)))
{
if (beginToEnd.GetCoordinate(axis) == 0) // parallel
{
if (beginToMin.GetCoordinate(axis) > 0 || beginToMax.GetCoordinate(axis) < 0)
return intersections; // segment is not between planes
}
else
{
var t1 = beginToMin.GetCoordinate(axis)/beginToEnd.GetCoordinate(axis);
var t2 = beginToMax.GetCoordinate(axis)/beginToEnd.GetCoordinate(axis);
var tMin = Math.Min(t1, t2);
var tMax = Math.Max(t1, t2);
if (tMin > tNear) tNear = tMin;
if (tMax < tFar) tFar = tMax;
if (tNear > tFar || tFar < 0) return intersections;
}
}
if (tNear >= 0 && tNear <= 1) intersections.Add(segmentBegin + beginToEnd * tNear);
if (tFar >= 0 && tFar <= 1) intersections.Add(segmentBegin + beginToEnd * tFar);
return intersections;
}
public enum Axis
{
X,
Y,
Z
}
public static double GetCoordinate(this Point3D point, Axis axis)
{
switch (axis)
{
case Axis.X:
return point.X;
case Axis.Y:
return point.Y;
case Axis.Z:
return point.Z;
default:
throw new ArgumentException();
}
}
public static double GetCoordinate(this Vector3D vector, Axis axis)
{
switch (axis)
{
case Axis.X:
return vector.X;
case Axis.Y:
return vector.Y;
case Axis.Z:
return vector.Z;
default:
throw new ArgumentException();
}
}
我不知道算法,但我想返回'null'是有點不尋常。一個空數組更好,很明顯沒有相交的點(長度= 0),並且您不需要在使用代碼中執行空檢查。 – RichK 2010-06-24 12:27:45
只是挑剔,但射線沒有終點 - 它在一個方向上是無限的。具有起點和終點的線是線段。 – 2010-06-25 00:19:31
好點,@RichK ...我糾正了我的問題。 – devuxer 2010-06-25 03:04:42