add modules section to basics

Author: monkstone

samples/processing_app/basics/modules/euler_ball.rb

@@ -0,0 +1,58 @@
+# encoding: UTF-8
+
+# module encapsulating run
+module Runner
+  def run
+    move
+    render
+    bounds_collision
+  end
+end
+
+# Euler Ball Class, we include Processing::Proxy module to access PApplet methods
+class EulerBall
+  include Processing::Proxy, Runner
+  attr_reader :pos, :spd, :radius, :bounds_x, :bounds_y
+
+  def initialize(position:, speed:, radius:)
+    @pos = position
+    @spd = speed
+    @radius = radius
+    @bounds_x = Bounds.new(lower: radius, upper: width - radius)
+    @bounds_y = Bounds.new(lower: radius, upper: height - radius)
+  end
+
+  def move
+    @pos += spd
+  end
+
+  def render
+    ellipse(pos.x, pos.y, radius * 2, radius * 2)
+  end
+
+  def bounds_collision
+    pos.x = bounds_x.position pos.x
+    spd.x *= -1 unless bounds_x.inside
+    pos.y = bounds_y.position pos.y
+    spd.y *= -1 unless bounds_y.inside
+  end
+end
+
+# Convenient boundary class, we only include MathTool module for constrain
+class Bounds
+  include Processing::MathTool
+  attr_reader :low, :high, :inside
+  def initialize(lower:, upper:)
+    @low = lower
+    @high = upper
+    @inside = true
+  end
+
+  # Returns the current position or the limit, sets the `inside` flag
+  def position(val)
+    @inside = true
+    return val if (low..high).cover? val
+    @inside = false
+    return constrain(val, low, high)
+  end
+end

samples/processing_app/basics/modules/euler_integration.rb

@@ -0,0 +1,32 @@
+#
+# Euler Integration (v01)
+# pos  +=  spd
+# sketch after Ira Greenwood 
+# Features first class keyword arguments, and use of modules
+#
+require_relative 'euler_ball'
+
+attr_reader :ball
+
+def setup
+  sketch_title 'Euler Integration'
+  @ball = EulerBall.new(
+    position: Vec2D.new(width / 2, height / 2),
+    # create a random direction vector, scaled by 3
+    speed: Vec2D.random * 3,
+    radius: 10
+  )
+end
+
+def draw
+  background(255)
+  # fill(255, 2)
+  # rect(-1, -1, width + 1, height + 1)
+  fill(0)
+  ball.run
+end
+
+def settings
+  size(400, 400)
+  smooth 4
+end