Method: Geometry::Polygon#<=>

Defined in:
lib/geometry/polygon.rb

#<=>(point) ⇒ Number

Test a Geometry::Point for inclusion in the receiver using a simplified winding number algorithm

Parameters:

Returns:



70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
 
# File 'lib/geometry/polygon.rb', line 70

def <=>(point)
    sum = edges.reduce(0) do |sum, e|
	direction = e.last.y <=> e.first.y
	# Ignore edges that don't cross the point's x coordinate
	next sum unless ((point.y <=> e.last.y) + (point.y <=> e.first.y)).abs <= 1

	if 0 == direction   # Special case horizontal edges
	    return 0 if ((point.x <=> e.last.x) + (point.x <=> e.first.x)).abs <= 1
	    next sum	    # Doesn't intersect
	else
	    is_left = e <=> point
	    return 0 if 0 == is_left
	    next sum unless is_left
	    sum += 0 <=> (direction + is_left)
	end
    end
    (0 == sum) ? -1 : 1
end