pure JRubyArt lenny explorer

Author: monkstone

contributed/lenny_explorer.rb

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+# lenny_explorer.rb
+# After 'The Explorer' by Leander Herzog, and a toxiclibs version by Karsten
+# Schmidt. This is a pure JRubyArt version by Martin Prout
+load_library :lenny
+attr_reader :path
+
+def settings
+  size(600, 600)
+end
+
+def setup
+  sketch_title 'Lenny Explorer'
+  no_fill
+  # @path = Path.new(
+  #   Boundary.new(
+  #     Rect.new(
+  #       Vec2D.new(10, 10),
+  #       Vec2D.new(width - 20, height - 20)
+  #     )
+  #   ),
+  #   10,
+  #   0.03,
+  #   3_000
+  # )
+  @path = Path.new(
+    Boundary.new(Circle.new(Vec2D.new(width / 2, height / 2), 250)),
+    10,
+    0.03,
+    3_000
+  )
+end
+
+def draw
+  background(255)
+  50.times { path.grow }
+  path.render(g)
+end
+
+def mouse_pressed
+  save_frame data_path('lenny.png')
+end

contributed/library/lenny/lenny.rb

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+require_relative 'lib/rect'
+require_relative 'lib/circle'
+require_relative 'lib/boundary'
+require_relative 'lib/path'
+require_relative 'lib/line2d'

contributed/library/lenny/lib/boundary.rb

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+# Duck typing Boundary
+class Boundary
+  attr_reader :bounds
+  def initialize(bounds)
+    @bounds = bounds
+  end
+
+  def contains?(vec)
+    bounds.contains?(vec)
+  end
+
+  def centroid
+    bounds.centroid
+  end
+end

contributed/library/lenny/lib/circle.rb

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+# For use with Boundary
+class Circle
+  attr_reader :centroid, :radius
+  def initialize(center, radius)
+    @centroid = center
+    @radius = radius
+  end
+
+  def contains?(vec)
+    centroid.dist(vec) < radius
+  end
+end

contributed/library/lenny/lib/line2d.rb

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+# Use to detect whether instances of line intersect
+class Line2D
+  attr_reader :a, :b
+  def initialize(a, b)
+    @a = a
+    @b = b
+  end
+
+  def intersecting?(line)
+    denom = (line.b.y - line.a.y) * (b.x - a.x) - (line.b.x - line.a.x) * (b.y - a.y)
+    na = (line.b.x - line.a.x) * (a.y - line.a.y) - (line.b.y - line.a.y) * (a.x - line.a.x)
+    nb = (b.x - a.x) * (a.y - line.a.y) - (b.y - a.y) * (a.x - line.a.x)
+    return false if denom.zero?
+
+    ua = na / denom
+    ub = nb / denom
+    (ua >= 0.0 && ua <= 1.0 && ub >= 0.0 && ub <= 1.0)
+  end
+end

contributed/library/lenny/lib/path.rb

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+# Stores and manipulates the path
+class Path
+  attr_reader :path, :last, :bounds, :cut, :theta, :delta, :speed, :searches
+
+  def initialize(bounds, speed, delta, history)
+    @bounds = bounds
+    @speed = speed
+    @delta = delta
+    @theta = 0
+    @path = (0..history).map { bounds.centroid.copy }
+    @searches = 0
+    @last = Vec2D.new(path.first)
+  end
+
+  def grow
+    @delta = rand(-0.2..0.2) if rand < 0.1
+    if !intersecting?
+      move
+    else
+      search
+    end
+  end
+
+  def move
+    @last = path.first
+    path.pop
+    @theta += delta
+    path.unshift last + Vec2D.new(speed * Math.cos(theta), speed * Math.sin(theta))
+    @searches = 0
+  end
+
+  def search
+    @theta += delta
+    path[0] = last + Vec2D.new(speed * Math.cos(theta), speed * Math.sin(theta))
+    @searches += 1
+  end
+
+  def render(gfx)
+    gfx.begin_shape
+    path.map { |vec| gfx.curve_vertex(vec.x, vec.y) }
+    gfx.end_shape
+  end
+
+  def intersecting?
+    return true unless bounds.contains?(path.first)
+
+    if searches < 100
+      a = Line2D.new(path[0], path[1])
+      (3...path.length).each do |i|
+        b = Line2D.new(path[i], path[i - 1])
+        return true if a.intersecting?(b)
+      end
+    end
+    false
+  end
+end

contributed/library/lenny/lib/rect.rb

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+# For use with Boundary
+class Rect
+  attr_reader :vec1, :vec2
+  def initialize(vec1, vec2)
+    @vec1 = vec1
+    @vec2 = vec2
+  end
+
+  def centroid
+    (vec1 + vec2) / 2
+  end
+
+  def contains?(vec)
+    xminmax = [vec1.x, vec2.x]
+    yminmax = [vec1.y, vec2.y]
+    return false if vec.x < xminmax[0]
+    return false if vec.x > xminmax[1]
+    return false if vec.y < yminmax[0]
+
+    vec.y < yminmax[1]
+  end
+end