ruby on rails -检查坐标路径是否交叉

Question

我有一堆坐标点，即((0,1)，(-1，-2))等。如何验证两个坐标点是否接触?

就像下面显示的(不太好)，当坐标(3,1)和(1,2)接触/交叉?

                |y
                |
                |- 2| (1,2)
                |   |
                |-----------| (3,1)
                |   |       |
----|---|---|---+---|---|---|----
x  -3  -2  -1   |   1   2   3
                |
                |
                |  -2
                |
                |  -3
                |

它们在点(1,1)相交/接触。我不需要交叉点，我只需要知道它们是否相交。

Answer 1

我将计算两个点从(x,y)到(x,0)和(0,y)的路径坐标，并简单地检查两个点的坐标之间是否存在交集。我相信这会产生你想要的结果。

# All coordinates on paths from (x,y) to (x,0) and from (x,y) to (0,y)
def path(point)
  x, y = point
  coords_x = (x >= 0 ? [*0..x] : [*x..0]).map { |c| [c, y] }
  coords_y = (y >= 0 ? [*0..y] : [*y..0]).map { |c| [x, c] }
  coords_x | coords_y
end
# p1 and p2 share a coordinate on their paths to (x,0) / (0,y) from (x,y)
def cross(p1, p2)
  ( path(p1) & path(p2) ).any?
end
p1 = [3,1]
p2 = [1,2]
cross(p1,p2) # => true
p1 = [0,0]
p2 = [0,-3]
cross(p1,p2) # => true
p1 = [-5,-5]
p2 = [-5,5]
cross(p1,p2) # => true
p1 = [-3,-3]
p2 = [3,3]
cross(p1,p2) # => false