Data commit

Task/Animate-a-pendulum/Ruby/animate-a-pendulum-1.rb

@@ -0,0 +1,63 @@
+require 'tk'
+
+$root = TkRoot.new("title" => "Pendulum Animation")
+$canvas = TkCanvas.new($root) do
+  width 320
+  height 200
+  create TkcLine, 0,25,320,25,   'tags' => 'plate', 'width' => 2, 'fill' => 'grey50'
+  create TkcOval, 155,20,165,30, 'tags' => 'pivot', 'outline' => "", 'fill' => 'grey50'
+  create TkcLine, 1,1,1,1, 'tags' => 'rod', 'width' => 3, 'fill' => 'black'
+  create TkcOval, 1,1,2,2, 'tags' => 'bob', 'outline' => 'black', 'fill' => 'yellow'
+end
+$canvas.raise('pivot')
+$canvas.pack('fill' => 'both', 'expand' => true)
+
+$Theta = 45.0
+$dTheta = 0.0
+$length = 150
+$homeX = 160
+$homeY = 25
+
+def show_pendulum
+  angle = $Theta * Math::PI / 180
+  x = $homeX + $length * Math.sin(angle)
+  y = $homeY + $length * Math.cos(angle)
+  $canvas.coords('rod', $homeX, $homeY, x, y)
+  $canvas.coords('bob', x-15, y-15, x+15, y+15)
+end
+
+def recompute_angle
+  scaling = 3000.0 / ($length ** 2)
+  # first estimate
+  firstDDTheta = -Math.sin($Theta * Math::PI / 180) * scaling
+  midDTheta = $dTheta + firstDDTheta
+  midTheta = $Theta + ($dTheta + midDTheta)/2
+  # second estimate
+  midDDTheta = -Math.sin(midTheta * Math::PI / 180) * scaling
+  midDTheta = $dTheta + (firstDDTheta + midDDTheta)/2
+  midTheta = $Theta + ($dTheta + midDTheta)/2
+  # again, first
+  midDDTheta = -Math.sin(midTheta * Math::PI / 180) * scaling
+  lastDTheta = midDTheta + midDDTheta
+  lastTheta = midTheta + (midDTheta + lastDTheta)/2
+  # again, second
+  lastDDTheta = -Math.sin(lastTheta * Math::PI/180) * scaling
+  lastDTheta = midDTheta + (midDDTheta + lastDDTheta)/2
+  lastTheta = midTheta + (midDTheta + lastDTheta)/2
+  # Now put the values back in our globals
+  $dTheta  = lastDTheta
+  $Theta = lastTheta
+end
+
+def animate
+  recompute_angle
+  show_pendulum
+  $after_id = $root.after(15) {animate}
+end
+
+show_pendulum
+$after_id = $root.after(500) {animate}
+
+$canvas.bind('<Destroy>') {$root.after_cancel($after_id)}
+
+Tk.mainloop

Task/Animate-a-pendulum/Ruby/animate-a-pendulum-2.rb

@@ -0,0 +1,57 @@
+Shoes.app(:width => 320, :height => 200) do
+  @centerX = 160
+  @centerY = 25
+  @length = 150
+  @diameter = 15
+
+  @Theta = 45.0
+  @dTheta = 0.0
+
+  stroke gray
+  strokewidth 3
+  line 0,25,320,25
+  oval 155,20,10
+
+  stroke black
+  @rod = line(@centerX, @centerY, @centerX, @centerY + @length)
+  @bob = oval(@centerX - @diameter, @centerY + @length - @diameter, 2*@diameter)
+
+  animate(24) do |i|
+    recompute_angle
+    show_pendulum
+  end
+
+  def show_pendulum
+    angle = (90 + @Theta) * Math::PI / 180
+    x = @centerX + (Math.cos(angle) * @length).to_i
+    y = @centerY + (Math.sin(angle) * @length).to_i
+
+    @rod.remove
+    strokewidth 3
+    @rod = line(@centerX, @centerY, x, y)
+    @bob.move(x-@diameter, y-@diameter)
+  end
+
+  def recompute_angle
+    scaling = 3000.0 / (@length **2)
+    # first estimate
+    firstDDTheta = -Math.sin(@Theta * Math::PI / 180) * scaling
+    midDTheta = @dTheta + firstDDTheta
+    midTheta = @Theta + (@dTheta + midDTheta)/2
+    # second estimate
+    midDDTheta = -Math.sin(midTheta * Math::PI / 180) * scaling
+    midDTheta = @dTheta + (firstDDTheta + midDDTheta)/2
+    midTheta = @Theta + (@dTheta + midDTheta)/2
+    # again, first
+    midDDTheta = -Math.sin(midTheta * Math::PI / 180) * scaling
+    lastDTheta = midDTheta + midDDTheta
+    lastTheta = midTheta + (midDTheta + lastDTheta)/2
+    # again, second
+    lastDDTheta = -Math.sin(lastTheta * Math::PI/180) * scaling
+    lastDTheta = midDTheta + (midDDTheta + lastDDTheta)/2
+    lastTheta = midTheta + (midDTheta + lastDTheta)/2
+    # Now put the values back in our globals
+    @dTheta  = lastDTheta
+    @Theta = lastTheta
+  end
+end

Task/Animate-a-pendulum/Ruby/animate-a-pendulum-3.rb

@@ -0,0 +1,104 @@
+#!/bin/ruby
+
+begin; require 'rubygems'; rescue; end
+
+require 'gosu'
+include Gosu
+
+# Screen size
+W = 640
+H = 480
+
+# Full-screen mode
+FS = false
+
+# Screen update rate (Hz)
+FPS = 60
+
+class Pendulum
+
+  attr_accessor :theta, :friction
+
+  def initialize( win, x, y, length, radius, bob = true, friction = false)
+    @win = win
+    @centerX = x
+    @centerY = y
+    @length = length
+    @radius = radius
+    @bob = bob
+    @friction = friction
+
+    @theta = 60.0
+    @omega = 0.0
+    @scale = 2.0 / FPS
+  end
+
+  def draw
+    @win.translate(@centerX, @centerY) {
+      @win.rotate(@theta) {
+        @win.draw_quad(-1, 0, 0x3F_FF_FF_FF, 1, 0, 0x3F_FF_FF_00, 1, @length, 0x3F_FF_FF_00, -1, @length, 0x3F_FF_FF_FF )
+        if @bob
+          @win.translate(0, @length) {
+            @win.draw_quad(0, -@radius, Color::RED, @radius, 0, Color::BLUE, 0, @radius, Color::WHITE, -@radius, 0, Color::BLUE )
+          }
+        end
+      }
+    }
+  end
+
+  def update
+    # Thanks to Hugo Elias for the formula (and explanation thereof)
+    @theta += @omega
+    @omega = @omega - (Math.sin(@theta * Math::PI / 180) / (@length * @scale))
+    @theta *= 0.999 if @friction
+  end
+
+end # Pendulum class
+
+class GfxWindow < Window
+
+  def initialize
+    # Initialize the base class
+    super W, H, FS, 1.0 / FPS * 1000
+    # self.caption = "You're getting sleeeeepy..."
+    self.caption = "Ruby/Gosu Pendulum Simulator (Space toggles friction)"
+
+    @n = 1  # Try changing this number!
+    @pendulums = []
+    (1..@n).each do |i|
+      @pendulums.push Pendulum.new( self, W / 2, H / 10, H * 0.75 * (i / @n.to_f), H / 60 )
+    end
+
+  end
+
+  def draw
+    @pendulums.each { |pen| pen.draw }
+  end
+
+  def update
+    @pendulums.each { |pen| pen.update }
+  end
+
+  def button_up(id)
+    if id == KbSpace
+      @pendulums.each { |pen|
+        pen.friction = !pen.friction
+        pen.theta = (pen.theta <=> 0) * 45.0 unless pen.friction
+      }
+    else
+      close
+    end
+  end
+
+  def needs_cursor?()
+    true
+  end
+
+end # GfxWindow class
+
+begin
+  GfxWindow.new.show
+rescue Exception => e
+  puts e.message, e.backtrace
+  gets
+end