判断两线段是否相交的C#代码

/// <summary>
/// 判断直线2的两点是否在直线1的两边。
/// </summary>
/// <param name="line1">直线1</param>
/// <param name="line2">直线2</param>
/// <returns></returns>
private bool CheckCrose(Line line1, Line line2)
{
PointF v1 = new PointF();
PointF v2 = new PointF();
PointF v3 = new PointF();

v1.X = line2.Start.X - line1.End.X;
v1.Y = line2.Start.Y - line1.End.Y;

v2.X = line2.End.X - line1.End.X;
v2.Y = line2.End.Y - line1.End.Y;

v3.X = line1.Start.X - line1.End.X;
v3.Y = line1.Start.Y - line1.End.Y;

return (CrossMul(v1, v3) * CrossMul(v2, v3) <= 0);

}
/// <summary>
/// 判断两条线段是否相交。
/// </summary>
/// <param name="line1">线段1</param>
/// <param name="line2">线段2</param>
/// <returns>相交返回真，否则返回假。</returns>
private bool CheckTwoLineCrose(Line line1, Line line2)
{
return CheckCrose(line1, line2) && CheckCrose(line2, line1);
}
/// <summary>
/// 计算两个向量的叉乘。
/// </summary>
/// <param name="pt1"></param>
/// <param name="pt2"></param>
/// <returns></returns>
private float CrossMul(PointF pt1, PointF pt2)
{
return pt1.X * pt2.Y - pt1.Y * pt2.X;
}