fiddling with particle

library/control_panel/control_panel.rb

@@ -59,7 +59,7 @@ def value
 
   # Creates check-box elements for control_panel
   class Checkbox < javax.swing.JCheckBox
-    def initialize(control_panel, name, proc=nil)
+    def initialize(control_panel, name, proc = nil)
       @control_panel = control_panel
       super(name.to_s)
       set_preferred_size(java.awt.Dimension.new(190, 64))
@@ -107,7 +107,7 @@ def display
       set_size 200, 30 + (64 * elements.size)
       set_default_close_operation javax.swing.JFrame::HIDE_ON_CLOSE
       set_resizable false
-      set_location($app.width + 10, 0) unless ($app.width + 10 > $app.displayWidth)
+      set_location($app.width + 10, 0) unless $app.width + 10 > $app.displayWidth
       panel.visible = true
     end
 
@@ -154,7 +154,7 @@ def set_feel(lf = 'metal')
       laf = lafinfo.select do |info|
         info.getName.eql? lf.capitalize
       end
-      javax.swing.UIManager.setLookAndFeel(laf[0].getClassName) 
+      javax.swing.UIManager.setLookAndFeel(laf[0].getClassName)
     end
   end
 

samples/processing_app/library/vecmath/vec2d/library/particle/particle.rb

@@ -40,16 +40,17 @@ def display
 
 class Particle
   include Processing::Proxy
-
+  
   GRAVITY = Vec2D.new(0, 0.1)
 
   attr_reader :center, :velocity, :lifespan, :s_shape, :part_size,
-  :width, :height, :sprite
-
+  :boundary_x, :boundary_y, :sprite
 
   def initialize width, height, sprite
-    @width, @height, @sprite = width, height, sprite
-    part_size = rand(10 .. 60)
+    @sprite = sprite
+    @boundary_x = Boundary.new(0, width)
+    @boundary_y = Boundary.new(0, height)
+    part_size = rand(10..60)
     # The particle is a textured quad
     @s_shape = create_shape
     s_shape.begin_shape(QUAD)
@@ -61,10 +62,8 @@ def initialize width, height, sprite
     s_shape.vertex(+part_size / 2.0, +part_size / 2.0, sprite.width, sprite.height)
     s_shape.vertex(-part_size / 2.0, +part_size / 2.0, 0, sprite.height)
     s_shape.end_shape
-
     # Initialize center vector
     @center = Vec2D.new
-
     # Set the particle starting location
     rebirth(width / 2.0, height / 2.0)
   end
@@ -87,8 +86,8 @@ def rebirth(x, y)
   # Is it off the screen, or its lifespan is over?
   def dead?
     return true if lifespan < 0
-    return true if center.y > height || center.y < 0
-    return true if center.x > width || center.x < 0
+    return true if boundary_y.exclude? center.y
+    return true if boundary_x.exclude? center.x
     false
   end
 
@@ -100,8 +99,15 @@ def update
     s_shape.set_tint(color(255, lifespan))
     # Move the particle according to its velocity
     s_shape.translate(velocity.x, velocity.y)
-    # and also update the center
+    # and also update the center location
     @center += velocity
   end
 end
 
+# unusually in this case we are looking for excluded values
+
+Boundary = Struct.new(:lower, :upper) do
+  def exclude? val
+    true unless (lower...upper).cover? val
+  end
+end