arc tesselation example

Author: monkstone

contributed/arc_tesselation.rb

@@ -0,0 +1,88 @@
+#!/usr/bin/env jruby
+require 'propane'
+
+# After an openprocessing sketch by Manoylov AC
+# https://www.openprocessing.org/user/23616/
+# press mouse to generate new pattern
+# use `c` key to toggle colored / greyscale
+# use 's' to save
+
+class ArcTesselation < Propane::App
+  attr_reader :cols, :coloured
+
+  PALETTE = %w[#152A3B #158ca7 #F5C03E #D63826 #0F4155 #7ec873 #4B3331].freeze
+
+  def settings
+    size(600, 600)
+  end
+
+  def setup
+    background 0
+    sketch_title 'Arc Tesselation'
+    # create a java primitive array of signed int
+    @cols = web_to_color_array(PALETTE)
+    stroke_weight 1.5
+    stroke_cap SQUARE
+    stroke(0, 200)
+    @coloured = true
+  end
+
+  def draw
+    arc_pattern
+  end
+
+  def sep_index(idx, length)
+    (idx - (length - 1) * 0.5).abs.floor
+  end
+
+  def sep_color(idx, number)
+    cols[sep_index(idx - 1, number + 1)]
+  end
+
+  def arc_pattern
+    circ_number = rand(4..10)
+    block_size = rand(30..70)
+    back_color = coloured ? cols.last : 255
+    fill(back_color)
+    rect(0, 0, width, height)
+    half_block = block_size / 2
+    two_block = 2 * block_size
+    grid(width + two_block, height + two_block, block_size, block_size) do |x, y|
+      push_matrix
+      translate x, y
+      rotate HALF_PI * rand(0..4)
+      circ_number.downto(0) do |i|
+        diam = two_block * i / (circ_number + 1)
+        ccolor = i < 2 || !coloured ? back_color : sep_color(i, circ_number)
+        fill ccolor
+        arc(-half_block, -half_block, diam, diam, 0, HALF_PI)
+        arc(half_block, half_block, diam, diam, PI, PI + HALF_PI)
+      end
+      pop_matrix
+    end
+    no_loop
+  end
+
+  def mouse_pressed
+    @cols = shuffle_array(cols) if coloured
+    loop
+  end
+
+  def key_typed
+    case key
+    when 'c', 'C'
+      @coloured = !coloured
+    when 's', 'S'
+      save(data_path('arc_pattern.png'))
+    end
+  end
+
+  # do a ruby shuffle! on a primitive java array
+  def shuffle_array(arr)
+    cols = arr.to_a
+    cols.shuffle!
+    cols.to_java(Java::int)
+  end
+end
+
+ArcTesselation.new

contributed/mandelbrot.rb

@@ -15,26 +15,25 @@ def setup
 
   # main drawing method
   def draw
-    (0...900).each do |x|
-      (0...600).each do |y|
-        c = Complex.new(map1d(x, (0...900), (-3..1.5)), map1d(y, (0...600), (-1.5..1.5)))
-        # mandel will return 0 to 20 (20 is strong)
-        #   map this to 0, 255 (and flip it)
-        pixels[x + y * 900] = color(255 - map1d(mandel(c, 20), (0..20), (0..255)).to_i)
-      end
+    grid(900, 600) do |x, y|
+      c = Complex(
+        map1d(x, (0...900), (-3..1.5)), map1d(y, (0...600), (-1.5..1.5))
+      )
+      # mandel will return 0..20 (20 is strong) map this to 255..0 (NB: reverse)
+      pixels[x + y * 900] = color(map1d(mandel(c, 20), (0..20), (255..0)).to_i)
     end
     update_pixels
   end
 
   # calculates the "accuracy" of a given point in the mandelbrot set
-  #    : how many iterations the number survives without becoming chaotic
+  # how many iterations the number survives without becoming chaotic
   def mandel(z, max = 10)
     score = 0
-    c = z.clone
+    c = z
     while score < max
       # z = z^2 + c
-      z.square
-      z.add c
+      z *= z
+      z += c
       break if z.abs > 2
       score += 1
     end
@@ -44,42 +43,6 @@ def mandel(z, max = 10)
   def settings
     size 900, 600
   end
-  # rolled my own Complex class
-  # including only the functionality I need (abs, square, add, to_s)
-  #
-  # Using this class, runs in ~12.5s on my MacBook Air
-  # compared to ~22s using ruby's Complex struct
-  class Complex
-    attr_accessor :real, :imag
-
-    def initialize(real, imag)
-      @real = real
-      @imag = imag
-    end
-
-    # squares a complex number - overwriting it
-    def square
-      r = real * real - imag * imag
-      i = 2 * real * imag
-      @real = r
-      @imag = i
-    end
-
-    # adds a given complex number
-    def add(c)
-      @real += c.real
-      @imag += c.imag
-    end
-
-    # computes the magnitude (HelperMethods dist is a safer version of Math.hypot)
-    def abs
-      Mandelbrot.dist(0, 0, real, imag)
-    end
-
-    def to_s
-      format('(%f+%fi)', real, imag)
-    end
-  end
 end
 
 Mandelbrot.new