gistfile1.rb

class String
	def dindent
		gsub(/^#{self[/\A\s+/]}/,'')
	end
end

class Turtle
	attr_accessor :x, :y, :a
	attr_reader :path
	def initialize( x=0, y=0, a=0 )
		@x, @y, @a = x, y, a
		@path = [ [@x, @y] ]
	end
	def fwd( dist )
		puts "fwd %.3f" % dist if $DEBUG
		@x += dist * Math.sin( @a * Math::PI/180 )
		@y -= dist * Math.cos( @a * Math::PI/180 )
		path << [@x, @y]
	end
	def rt( angle )
		puts " rt %.3f" % angle if $DEBUG
		@a += angle
	end
	def lt( angle )
		puts " lt %.3f" % angle if $DEBUG
		@a -= angle
	end
	def koch(dist,angle=66,iterations=6,bloat=1,curl=1)
		if iterations==0
			fwd dist
		else
			d2 = dist/2
			a2 = angle*2
			
			koch(d2,angle,iterations-1,bloat,curl)
			lt(angle)
			koch(d2*bloat*curl,angle,iterations-1,bloat,curl)
			rt(a2)
			koch(d2*bloat,angle,iterations-1,bloat,curl)
			lt angle
			koch(d2*curl,angle,iterations-1,bloat,curl)
		end
	end
	def spark(dist,angle=66,iterations=6)
		if iterations==0
			fwd dist
		else
			a2 = angle*2
			
			spark(dist,angle,iterations-1)
			lt angle
			spark(dist,angle,iterations-1)
			rt a2 
			spark(dist*2,angle,iterations-1)
			lt a2
			spark(dist,angle,iterations-1)
			rt angle
			spark(dist,angle,iterations-1)
		end
	end
	def spark2(dist,angle=66,iterations=6)
		if iterations==0
			fwd dist
		else
			d3 = dist/3.0
			da = dist/(12*Math.cos(angle*Math::PI/180))
			a2 = angle*2
			
			spark2(d3,angle,iterations-1)
			lt angle
			spark2(da,angle,iterations-1)
			rt a2 
			spark2(2*da,angle,iterations-1)
			lt a2
			spark2(da,angle,iterations-1)
			rt angle
			spark2(d3,angle,iterations-1)
		end
	end
	def svg( file )
		x = @path.map{ |p| p[0] }
		y = @path.map{ |p| p[1] }
		minx = x.min
		maxx = x.max
		miny = y.min
		maxy = y.max
		
		File.open(file,'w') do |f|
			f << <<-ENDSVG
				<svg width='100%' height='100%' xmlns='http://www.w3.org/2000/svg' viewBox='#{"%.2f %.2f %.2f %.2f" % [minx, miny, maxx-minx, maxy-miny] }'>
					<path d='M #{ "%.2f %.2f" % @path.first } #{@path[1..-1].map{ |p| "L %.2f %.2f" % p }.join(" ")}' fill='none' stroke='black' stroke-width='#{(maxy-miny)/400.0}'/>
				</svg>
			ENDSVG
		end
	end
	
	def self.animsvg( file, duration, *turtles )
		paths  = turtles.flatten.map{ |turtle| turtle.path }

		points = paths.inject([]){ |all,path| all.concat(path) }
		x = points.map{ |p| p[0] }
		y = points.map{ |p| p[1] }
		minx  = x.min
		maxx  = x.max
		miny  = y.min
		maxy  = y.max
		width  = maxx - minx
		height = maxy - miny
		stroke = height/1000.0

		path_datas = paths.map{ |path| "M %.0f %.0f #{'L %.0f %.0f '*(path.length-1)}" % path.flatten }
		
		File.open(file,'w') do |f|
			f << <<-ENDSVG.dindent
				<svg width='100%' height='100%' xmlns='http://www.w3.org/2000/svg' viewBox='#{ "%.2f %.2f %.2f %.2f" % [minx, miny, width, height] }'>
					<path d='#{path_datas.first}' fill='none' stroke='black' stroke-width='#{stroke}'>
					#{
						(1...path_datas.length).map{ |i|
							"<animate attributeType='XML' attributeName='d' from='#{path_datas[i-1]}' to='#{path_datas[i]}' begin='#{(i-1)*duration}s' dur='#{duration}s' fill='#{i==(path_datas.length-1) ? 'freeze' : 'remove'}' />"
						}.join("\n\t")
					}
					</path>
				</svg>
			ENDSVG
		end
	end
end


if __FILE__==$0
	turtles = []
	sides = 3
	30.step(74,1) do |a|
		turtle = Turtle.new(0,0,90)
		turtles << turtle
		sides.times do
			turtle.spark2(1000,a,4)
			turtle.rt 360.0/sides
		end
	end
	Turtle.animsvg( ARGV[0] || "out.svg",0.1, turtles )	

	# $DEBUG = true
	# turtle = Turtle.new(0,0,90)
	# turtle.spark2(1000,70,2)
	# turtle.svg( ARGV[0] || "out.svg" )
end