triangle.rb

w, h = 200.0, 200.0
vertexes = [[130.0,80.0], [50.0,50.0], [60.0,140.0]]


def ext(a,b) 11*a-10*b end
lines = vertexes.combination(2).map do |(x1,y1),(x2,y2)|
  [[ext(x1,x2),ext(y1,y2)],[ext(x2,x1),ext(y2,y1)]]
end

ratios = [[1,0,0].permutation, [1,1,0].permutation, [4,-1,0].permutation, [3,3,-2].permutation, [5,-1,-1].permutation, [[1,1,1]]].map(&:to_a).flatten(1).uniq
xsys = vertexes.transpose
points = ratios.map do |ratio|
  xsys.map do |vs|
    vs.zip(ratio).map{|v,r|v*r}.inject(&:+) / ratio.inject(&:+)
  end
end


puts <<EOF
%!PS-Adobe-3.1 EPSF-3.0
%%BoundingBox: 0 0 #{w} #{h}

#{lines.map{|(x1,y1),(x2,y2)|"#{x1} #{y1} moveto #{x2} #{y2} lineto stroke"}.join("\n")}

1 0 0 setrgbcolor
#{points.map{|x,y|"#{x} #{y} 3 0 360 arc closepath fill"}.join("\n")}

showpage
EOF