circle_generator.rb

#!/usr/bin/ruby

# inkscape -b '#ffffff' -e circles.png -w 3000 circles.svg

# gem install color-tools
require 'color'
# http://code.google.com/p/chipmunk-physics/ 
# svn checkout http://chipmunk-physics.googlecode.com/svn/trunk/ chipmunk-physics-read-only
# cmake -D BUILD_RUBY_EXT=ON . 
# make && sudo make install
require 'chipmunk'
# gem install progressbar
require 'progressbar'

def random(from, to = nil)
  if to
    rand()*(to - from) + from
  else
    rand()*from
  end
end

def hsl_to_html(h, s, l)
  Color::HSL.new(h*3.6, s, l).html
end

class Circle
  attr_reader :x, :y, :radius

  class<<self 
    attr_reader :circles
    def add_circle(c)
      @circles << c
    end

    def clear_circles
      @circles = []
    end

    def collide_any?(circle)
      @circles.each do |c|
        if c.collide?(circle)
          return true
        end
      end
      return false
    end
  end 

  def initialize(x, y, radius)
    @x, @y, @radius = x, y, radius
  end

  def collide?(circle)
    # compare the distance to combined radii
    dx = circle.x - self.x
    dy = circle.y - self.y
    radii = self.radius + circle.radius
    return dx*dx + dy*dy < radii*radii
  end

end

NUM_CIRCLES = 1000
WIDTH = HEIGHT = 1000
MARGIN = 25
#COLORS_START = [0, 47, 25, 12, 60, 90]
COLORS_START = [0, 57, 22, 9]

pbar = ProgressBar.new("circles", NUM_CIRCLES*COLORS_START.size)
$circles = []

#color_start = COLORS_START.at(random(COLORS_START.size))
COLORS_START.each_with_index do |color_start, color_index|
  Circle.clear_circles
  translation = [(color_index%2)*WIDTH + MARGIN, (color_index/2)*HEIGHT + MARGIN]
  while Circle.circles.size < NUM_CIRCLES
    radius = random(5, 180)
    x = random(WIDTH - MARGIN - 2*radius) + radius 
    y = random(HEIGHT - MARGIN - 2*radius) + radius
    circle = Circle.new(x, y, radius)

    next if Circle.collide_any?(circle)
    Circle.add_circle(circle)
    r = radius
    circle = { 'x' => circle.x + translation[0], 
               'y' => circle.y + translation[1], 
               #'radius' => radius, 
               'circles' => []
             }
    while r > 1
      color = hsl_to_html(random(0, 8) + color_start, random(90, 100), 50)
      circle['circles'] << [r, color]
      r -= random(1, 30)
    end
    $circles << circle
    pbar.inc
  end
end
File.open("circles.yaml", "w") { |f| f.puts({'width' => WIDTH*2 + MARGIN, 'height' => HEIGHT*2 + MARGIN, 'circles' => $circles }.to_yaml) }

generate_svgs.rb

#!/usr/bin/env ruby

require 'chipmunk'
require 'progressbar'
require 'yaml'

WIDTH = HEIGHT = 600
DT = 1.0/10.0

$space = CP::Space.new
#$space.damping = 1
#$space.gravity = CP::Vec2.new(0, 100)

class Circle
  attr_reader :body, :radius
  
  def initialize(x, y, circles)
    @circles = circles
    @radius = @circles.first[0] + @circles.first[0]*0.05
    @body = CP::Body.new(0.01*@radius, 0.0001)
    @body.p = CP::Vec2.new(x, y) # position
    #@body.velocity = CP::Vec2.new(1.0, 2.0) # velocity
    #@body.angle = (3*Math::PI/2.0) # angle in radians; faces towards top of screen
    @shape = CP::Shape::Circle.new(@body, @radius, CP::Vec2.new(0.0, 0.0))
    $space.add_body(@body)
    $space.add_shape(@shape)
  end

  def x
    @body.p.x
  end

  def y
    @body.p.y
  end

  def to_svg
    str = ""
    #str << "<g>"
    @circles.each do |c|
      str << %|<circle cx="#{x}" cy="#{y}" r="#{c[0]}" fill="#{c[1]}"/>|
    end
    #str << "</g>"
    str
  end
end

$data = YAML::load_file("circles.yaml")

$circles = $data['circles'].collect do |c| 
  x = c['x'] + 1000
  y = c['y'] + 1000
  Circle.new(x, y, c['circles']) 
end

=begin
cols = 10
$circles = (0...100).collect do |i| 
  Circle.new((i%cols)*20 + 100, (i/cols)*25 + 100)
end
=end

x = 500
y = 1500
circles = [
  [ 50, '#ddd' ],
  [ 35, '#aaa' ],
  [ 22, '#222' ],
  [ 15, '#fff' ],
  [ 5, '#bbb' ]
]

shoot_ball = Circle.new(x, y, circles)
#shoot_ball.body.v = CP::Vec2.new(300, 0)
shoot_ball.body.apply_force(CP::Vec2.new(1000, 0), CP::Vec2.new(0, 0))
shoot_ball.body.m = 1
$circles << shoot_ball

x = 3500
y = 2500
shoot_ball = Circle.new(x, y, circles)
#shoot_ball.body.velocity = CP::Vec2.new(-300, 0)
shoot_ball.body.apply_force(CP::Vec2.new(-1000, 0), CP::Vec2.new(0, 0))
shoot_ball.body.m = 1
$circles << shoot_ball

NUM_FRAMES = 1000
pbar = ProgressBar.new('frame', NUM_FRAMES)
NUM_FRAMES.times do |frame_num|
  $space.step(DT)
  #next unless frame_num % 25 == 0
  w = $data["width"]*2
  h = $data["height"]*2
  outfile = "tmp/circle_%05d.svg" % frame_num
  f = File.open(outfile, "w")
  f.puts <<EOF
<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg width="#{w}" height="#{h}" version="1.1" xmlns="http://www.w3.org/2000/svg">
<rect x="0" y="0" fill="white" width="#{w}" height="#{h}" />
EOF

  $circles.each do |circle|
    f.puts circle.to_svg
  end
  f.puts "</svg>"
  f.close
  pbar.inc
end

#exit
#system("java -jar /usr/share/java/batik-1.7.jar -w 600 -d tmp/ tmp/*.svg") || exit!
#apt-get install libbatik-java
system("rasterizer -w 600 -d tmp/ tmp/*.svg") || exit!
#system("mencoder -o test.avi -ovc lavc -mf type=png:fps=25 mf://tmp/*.png") || exit!
system("ffmpeg -r 25 -i tmp/circle%05d.png -y -an test.avi") || exit!