小编典典

检查同一圆上的两个线段是否重叠/相交

algorithm

给定同一个圆的两个圆段:A = [a1,a2]和B = [b1,b2],其中:

  • a1,a2,b1,b2的值介于-inf和+ inf之间
  • a1 <= a2; b1 <= b2
  • a2-a1 <= 360;b2-b1 <= 360

如何确定这两个圆弧段是否重叠?(即,如果它们相交或接触至少一点)

例子:

A=[  -45°,    45°]; B=[   10°,   20°] ==> overlap
A=[  -45°,    45°]; B=[   90°,  180°] ==> no overlap
A=[  -45°,    45°]; B=[  180°,  360°] ==> overlap
A=[ -405°,  -315°]; B=[  180°,  360°] ==> overlap
A=[-3600°, -3601°]; B=[ 3601°, 3602°] ==> overlap (touching counts as overlap)
A=[ 3600°,  3601°]; B=[-3601°,-3602°] ==> overlap (touching counts as overlap)
A=[    -1°,    1°]; B=[ 3602°, 3603°] ==> no overlap

这看起来像是一个看似简单的问题,但是我无法解决这个问题。目前,我对解决方案有一个基本的想法,该方案涉及将每个线段在相交0°时分成两部分,但是我不确定是否能涵盖所有情况,并且我想知道是否有一个优雅的公式。


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2020-07-28

共1个答案

小编典典

如@admaoldak所述,请先将度数标准化:

a1_norm = a1 % 360
a2_norm = a2 % 360
b1_norm = b1 % 360
b2_norm = b2 % 360

现在检查b1是否在(a1,a2)之内,

def intersect(b, as, ae
    Intersect = False
    If as > ae:
        if b >= as or b <= ae:
            return True
    Else:
        if b>=as and b<=ae:
            return True
    return False

最终答案是:

intersect(b1_norm,a1_norm,a2_norm)||intersect(b2_norm,a1_norm,a2_norm)||
intersect(a1_norm,b1_norm,b2_norm)||intersect(a2_norm,b1_norm,b2_norm)
2020-07-28