point_to_line / point_to_line_points

point_to_line.rb

# point_to_line
# point: (x0, y0)
# line: ax+by+c=0
def point_to_line x0,y0, a,b,c
  (a*x0+b*y0+c).abs / Math.sqrt(a**2+b**2)
end

# point: (x0, y0) 
# line: between (x1, y1), (x2, y2)
def point_to_line_points x0,y0, x1,y1, x2,y2
  ((y2-y1)*x0-(x2-x1)*y0+x2*y1-y2*x1).abs / Math.sqrt((x2-x1)**2+(y2-y1)**2)
end