added gallery 10: A Very Simple Boids

README.mdown

@@ -2,7 +2,7 @@ Shoes Tutorial Note
 ===================
 **- For the Shoes App Rookie Creators -**
 
-May 24th, 2009 by ashbb (Satoshi Asakawa), citizen428 (Michael Kohl), kotp (Victor H. Goff III)
+May 25th, 2009 by ashbb (Satoshi Asakawa), citizen428 (Michael Kohl), kotp (Victor H. Goff III)
 
 Table of contents
 -----------------
@@ -84,7 +84,7 @@ Table of contents
 10. [01000 Acknowledgment](http://github.com/ashbb/shoes_tutorial_html/tree/master/mdowns/01000_Acknowledgment.mdown)
 11. Fancy Gallery
 	- [01110 Fancy Gallery 1-5 (gallery1.rb, gallery1-1.rb, gallery2.rb, gallery3.rb, gallery4.rb, gallery4-1.rb, gallery5.rb)](http://github.com/ashbb/shoes_tutorial_html/tree/master/mdowns/01110_Fancy_Gallery_1-5.mdown)
-	- [01120 Fancy Gallery 6-10 (gallery6.rb, gallery7.rb, gallery8.rb, gallery9.rb)](http://github.com/ashbb/shoes_tutorial_html/tree/master/mdowns/01120_Fancy_Gallery_6-10.mdown)
+	- [01120 Fancy Gallery 6-10 (gallery6.rb, gallery7.rb, gallery8.rb, gallery9.rb, gallery10.rb, gallery10-rules.rb, gallery10-image.rb)](http://github.com/ashbb/shoes_tutorial_html/tree/master/mdowns/01120_Fancy_Gallery_6-10.mdown)
 12. Built-in Samples
 
 	- [01201 simple-accordion (simple-accordion.rb)](http://github.com/ashbb/shoes_tutorial_html/tree/master/mdowns/01201_simple-accordion.mdown)

changelog.mdown

@@ -1,5 +1,6 @@
 Change log:
 -----------
+May 25th, 2009: Added gallery 10.   
 May 24th, 2009: Added a new chapter 00611   
 May 17th, 2009: Added a new chapter 00610   
 May 09th, 2009: Added a new chapter 00609   

mdowns/01120_Fancy_Gallery_6-10.mdown

@@ -298,3 +298,108 @@ Look at the [online demo](http://www.rin-shun.com/rubylearning/shoes/scatter_pac
 ![gallery9.png](http://github.com/ashbb/shoes_tutorial_html/raw/master/images/gallery9.png)
 
 
+
+
+Gallery No.10
+-------------
+A Very Simple Boids Program.
+
+Paul Harris introduced the following fancy Shoes app in the Shoes course 4th batch.
+
+[Hungry Boids](http://the-shoebox.org/apps/45)
+
+I read the code and found the link to this web site:   
+[Boids Pseudocode](http://www.vergenet.net/~conrad/boids/pseudocode.html)
+
+So simple! Most impressive indeed!
+
+I attempted coding a tiny Shoes app just by following the algorithm.
+
+Look at [online demo](http://www.rin-shun.com/rubylearning/shoes/a_very_simple_boids.swf.html).
+
+	# gallery10.rb
+	# http://www.vergenet.net/~conrad/boids/pseudocode.html
+	require 'matrix'
+	require 'gallery10-image'
+	require 'gallery10-rules'
+
+	Shoes.app :title => 'A Very Simple Boids v0.1' do
+	  extend Rules
+	  @boids = []
+	  N.times do
+	    x, y = rand(200), rand(200)
+	    vx, vy = rand(2), rand(2)
+	    @boids << image('../images/gallery10-kamome.png', 
+	      :left => x, :top => y, :pos => Vector[x, y], :vel => Vector[vx, vy])
+	  end
+	  
+	  animate 12 do
+	    @boids.each do |boid|
+	      boid.vel = boid.vel + rule1(boid) + rule2(boid) + rule3(boid) + rule4(boid)
+	      boid.pos = boid.pos + boid.vel
+	      boid.move boid.x, boid.y
+	    end
+	  end
+	end
+
+
+4 rules:
+
+
+	# gallery10-rules.rb
+	N = 12
+	BOUND = 3
+
+	module Rules
+	  def rule1 boid
+	    c = @boids.collect{|b| b.pos}.inject{|i, j| i + j} - boid.pos
+	    c *= 1 / (N - 1.0)
+	    (c - boid.pos) * 0.01
+	  end
+	  
+	  def rule2 boid
+	    c = Vector[0, 0]
+	    @boids.each do |b|
+	      dist = b.pos - boid.pos
+	      (c -= b.pos - boid.pos) if (b != boid and dist[0].to_i.abs < 5 and dist[1].to_i.abs < 5)
+	    end
+	    c
+	  end
+	  
+	  def rule3 boid
+	    c = @boids.collect{|b| b.vel}.inject{|i, j| i + j} - boid.vel
+	    c *= 1 / (N - 1.0)
+	    (c - boid.vel) * (1 / 16.0)
+	  end
+	  
+	  def rule4 boid
+	    vx, vy = 0, 0
+	    x, y = boid.pos[0], boid.pos[1]
+	    vx = BOUND if x < 20
+	    vx = -BOUND if x > 580
+	    vy = BOUND if y < 20
+	    vy = -BOUND if y > 480
+	    Vector[vx, vy]
+	  end
+	end
+
+
+Helper methods for writing the simple code:
+
+
+	# gallery10-image.rb
+	class Shoes::Image
+	  [:vel, :pos].each do |m|
+	    define_method(m){style[m]}
+	    define_method("#{m}="){|arg| style m => arg}
+	  end
+	  
+	  [:x, :y].each_with_index{|m, i| define_method(m){pos[i].to_i}}
+	end
+
+**gallery10.png**
+
+![gallery10.png](http://github.com/ashbb/shoes_tutorial_html/raw/master/images/gallery10.png)
+
+
+

src/gallery10-image.rb

@@ -0,0 +1,9 @@
+# gallery10-image.rb
+class Shoes::Image
+  [:vel, :pos].each do |m|
+    define_method(m){style[m]}
+    define_method("#{m}="){|arg| style m => arg}
+  end
+
+  [:x, :y].each_with_index{|m, i| define_method(m){pos[i].to_i}}
+end

src/gallery10-rules.rb

@@ -0,0 +1,36 @@
+# gallery10-rules.rb
+N = 12
+BOUND = 3
+
+module Rules
+  def rule1 boid
+    c = @boids.collect{|b| b.pos}.inject{|i, j| i + j} - boid.pos
+    c *= 1 / (N - 1.0)
+    (c - boid.pos) * 0.01
+  end
+
+  def rule2 boid
+    c = Vector[0, 0]
+    @boids.each do |b|
+      dist = b.pos - boid.pos
+      (c -= b.pos - boid.pos) if (b != boid and dist[0].to_i.abs < 5 and dist[1].to_i.abs < 5)
+    end
+    c
+  end
+
+  def rule3 boid
+    c = @boids.collect{|b| b.vel}.inject{|i, j| i + j} - boid.vel
+    c *= 1 / (N - 1.0)
+    (c - boid.vel) * (1 / 16.0)
+  end
+
+  def rule4 boid
+    vx, vy = 0, 0
+    x, y = boid.pos[0], boid.pos[1]
+    vx = BOUND if x < 20
+    vx = -BOUND if x > 580
+    vy = BOUND if y < 20
+    vy = -BOUND if y > 480
+    Vector[vx, vy]
+  end
+end

src/gallery10.rb

@@ -0,0 +1,24 @@
+# gallery10.rb
+# http://www.vergenet.net/~conrad/boids/pseudocode.html
+require 'matrix'
+require 'gallery10-image'
+require 'gallery10-rules'
+
+Shoes.app :title => 'A Very Simple Boids v0.1' do
+  extend Rules
+  @boids = []
+  N.times do
+    x, y = rand(200), rand(200)
+    vx, vy = rand(2), rand(2)
+    @boids << image('../images/gallery10-kamome.png', 
+      :left => x, :top => y, :pos => Vector[x, y], :vel => Vector[vx, vy])
+  end
+
+  animate 12 do
+    @boids.each do |boid|
+      boid.vel = boid.vel + rule1(boid) + rule2(boid) + rule3(boid) + rule4(boid)
+      boid.pos = boid.pos + boid.vel
+      boid.move boid.x, boid.y
+    end
+  end
+end

tools/table_of_contents.txt

@@ -2,7 +2,7 @@ Shoes Tutorial Note
 ===================
 **- For the Shoes App Rookie Creators -**
 
-May 24th, 2009 by ashbb (Satoshi Asakawa), citizen428 (Michael Kohl), kotp (Victor H. Goff III)
+May 25th, 2009 by ashbb (Satoshi Asakawa), citizen428 (Michael Kohl), kotp (Victor H. Goff III)
 
 Table of contents
 -----------------