├── README.textile
└── tunnel.rb


/README.textile:
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1 | h2. Tunnel Algorithm in Ruby Processing
2 | 
3 | !http://dl.getdropbox.com/u/221414/blogs/tunnel.png!
4 | 
5 | "Video":http://screencast.com/t/PBWXTvJdVfP
6 | 


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/tunnel.rb:
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  1 | # Tunnel
  2 | 
  3 | class Tunnel < Processing::App
  4 | 
  5 |   module Lookup
  6 |     def self.generate
  7 |       @sin_table = []
  8 |       @cos_table = []
  9 | 
 10 |       @precision = 0.2
 11 |       @inverse = 1.0 / @precision
 12 |       @table_length = (360.0 * @inverse).to_i
 13 | 
 14 |       @direction_x = 5
 15 |       @direction_y = 0
 16 | 
 17 |       (0..@table_length).each do |i|
 18 |         @sin_table[i] = Math.sin i * (Math::PI / 180) * @precision
 19 |         @cos_table[i] = Math.cos i * (Math::PI / 180) * @precision
 20 |       end
 21 |     end
 22 | 
 23 |     def self.change_direction
 24 |       @direction_x += 0.5 - rand if rand > 0.98
 25 |       @direction_y += 0.5 - rand if rand > 0.98
 26 |     end
 27 | 
 28 |     def self.sin_table
 29 |       @sin_table
 30 |     end
 31 | 
 32 |     def self.cos_table
 33 |       @cos_table
 34 |     end
 35 | 
 36 |     def self.table_length
 37 |       @table_length
 38 |     end
 39 | 
 40 |     def self.inverse
 41 |       @inverse
 42 |     end
 43 | 
 44 |     def self.direction_x ; @direction_x ; end
 45 |     def self.direction_y ; @direction_y ; end
 46 |   end
 47 | 
 48 |   class Ring
 49 |     attr_reader :diameter, :offset
 50 | 
 51 |     def initialize(x, y, diameter, offset, width, height)
 52 |       @x, @y, @diameter, @offset = x, y, diameter, offset
 53 |       @step = 10
 54 |       @width = width
 55 |       @height = height
 56 |       # Set these to 1 + rand(3) for a nice effect in no delete mode
 57 |       @grow_speed = 2.0
 58 |       @spin_speed = 2.5
 59 |       @base_colour = color(80, 30, 30)
 60 | 
 61 |       @direction_x = Lookup.direction_x
 62 |       @direction_y = Lookup.direction_y
 63 |     end
 64 | 
 65 |     def update(base_colour = nil)
 66 |       @base_colour = base_colour if base_colour
 67 | 
 68 |       # Needs to get faster as it gets wider
 69 |       @diameter += @grow_speed + (@diameter * Lookup.sin_table[(@diameter % Lookup.table_length) / 8])
 70 |       @offset += @spin_speed
 71 |       
 72 |       # These can wrap, but this isn't used in tunnel mode
 73 |       @diameter = 0 if @diameter >= Lookup.table_length
 74 |       @offset = 0 if @offset >= Lookup.table_length
 75 | 
 76 |       @x = @x + (Lookup.cos_table[@offset] * @direction_x)
 77 |       @y = @y + (Lookup.sin_table[@offset] * @direction_y)
 78 |     end
 79 | 
 80 |     def draw
 81 |       radius = 16 + @height * Lookup.sin_table[@diameter]
 82 | 
 83 |       (0..360/@step).each do |i|
 84 |         i *= @step
 85 |         theta = (i * Lookup.inverse + @offset) % Lookup.table_length
 86 | 
 87 |         x = @x + (Lookup.cos_table[theta] * radius)
 88 |         y = @y + (Lookup.sin_table[theta] * radius)
 89 |          
 90 |         plot x, y
 91 |       end
 92 |     end
 93 | 
 94 |     def plot(x, y)
 95 |       set x, y, @base_colour
 96 |     end
 97 |   end
 98 | 
 99 |   def setup
100 |     color_mode RGB, 255
101 |     background 0
102 |     
103 |     Lookup.generate
104 | 
105 |     @ring_size_limit = 256
106 |     @palette = make_palette
107 |     @rings = []
108 | 
109 |     add_ring 1, 1
110 | 
111 |     frame_rate 30
112 |   end
113 |   
114 |   def draw
115 |     background 0
116 |     @rings.each do |ring|
117 |       # The widest the ring can be needs to be calculated here
118 |       colour_index = (ring.diameter.to_f / 60) * 255
119 |       base_colour = @palette[colour_index]
120 |       ring.update(base_colour)
121 |       ring.draw
122 |     end
123 |   
124 |     @rings.delete_if { |ring| ring.diameter > 400 }
125 | 
126 |     if @rings.size < @ring_size_limit and @rings.last.diameter > 6
127 |       Lookup.change_direction
128 |       add_ring 0, @rings.last.offset + 2
129 |     end
130 |   end
131 | 
132 |   def add_ring(diameter, offset)
133 |     @rings << Ring.new(width / 2, height / 2, diameter, offset, width, height)
134 |   end
135 | 
136 |   def make_palette
137 |     palette = []
138 |     # Create the bands of colour for the palette (256 is the maximum colour)
139 |     limit = 256
140 |     base_colour = 1
141 |     (0..limit).each do |i|
142 |       offset = base_colour + i
143 |       offset = 255 if offset > 255
144 |       palette[i] = [base_colour, base_colour, offset]
145 | 
146 |       base_colour += Lookup.sin_table[i]
147 |     end
148 |     palette.collect { |p| color(*p) }
149 |   end
150 | end
151 | 
152 | Tunnel.new :title => "Tunnel", :width => 640, :height => 480
153 | 


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