Fraction Sums

# fraction_sums.rb, by Martin Prout
attr_reader :f, :two, :three, :four, :five, :six

def setup
  sketch_title 'Math Blackboard'
  @f = createFont('Arial', 24, true)
  half = 1 / 2r     # since ruby 2.1.0 (and jruby-9.0.0.0)
  third = 1 / 3r
  quarter = 1 / 4r
  fifth = 1 / 5r
  sixth = 1 / 6r
  seventh = 1 / 7r
  format2 = '%s + %s                                     = %s'
  format3 = '%s + %s + %s                            = %s'
  format4 = '%s + %s + %s + %s                   = %s'
  format5 = '%s + %s + %s + %s + %s          = %s'
  format6 = '%s + %s + %s + %s + %s + %s = %s'
  sum2 =  half + third
  result2 = numeric_to_mixed_number(sum2)
  @two = format(format2, half, third, result2)
  sum3 =  half + third + quarter
  result3 = numeric_to_mixed_number(sum3)
  @three = format(format3, half, third, quarter, result3)
  sum4 =  half + third + quarter + fifth
  result4 = numeric_to_mixed_number(sum4)
  @four = format(format4, half, third, quarter, fifth, result4)
  sum5 =  half + third + quarter + fifth + sixth
  result5 = numeric_to_mixed_number(sum5)
  @five = format(format5, half, third, quarter, fifth, sixth, result5)
  sum6 =  half + third + quarter + fifth + sixth + seventh
  result6 = numeric_to_mixed_number(sum6)
  @six = format(format6, half, third, quarter, fifth, sixth, seventh, result6)
end

def draw
  background 10
  text_font(f, 24)
  fill(220)
  text('Math Blackboard JRubyArt', 110, 50)
  text(two, 100, 80)
  text(three, 100, 105)
  text(four, 100, 130)
  text(five, 100, 155)
  text(six, 100, 180)
end

def numeric_to_mixed_number(amount)
  amount_as_integer = amount.to_i
  if (amount_as_integer != amount.to_f) && (amount_as_integer > 0)
    fraction = amount - amount_as_integer
    format('%s %s', amount_as_integer, fraction)
  else
    amount.to_s
  end
end

def settings
  size 640, 250
  smooth 4
end

Bresenham's Algorithm in JRubyArt

After ruby-processing version, published by norioc on qiita

# ruby-processing sketch
# http://qiita.com/norioc/items/99514cb659aad03ab7d7
# http://aidiary.hatenablog.com/entry/20050402/1251514618
N = 15
attr_reader :rows, :cols

def setup
  sketch_title 'Bresenham`s Algorithm'
  @rows = height / N
  @cols = width / N
end

def settings
  size 400, 400
end

def build_line(from:, to:)
  next_x = from.x
  next_y = from.y
  delta_x = to.x - from.x
  delta_y = to.y - from.y
  step_x = delta_x < 0 ? -1 : 1
  step_y = delta_y < 0 ? -1 : 1
  delta_x = (delta_x * 2).abs
  delta_y = (delta_y * 2).abs
  b_line = Array.new(1, Vec2D.new(next_x, next_y))
  if delta_x > delta_y
    fraction = delta_y - delta_x / 2
    while next_x != to.x
      if fraction >= 0
        next_y += step_y
        fraction -= delta_x
      end
      next_x += step_x
      fraction += delta_y
      b_line << Vec2D.new(next_x, next_y)
    end
  else
    fraction = delta_x - delta_y / 2
    while next_y != to.y
      if fraction >= 0
        next_x += step_x
        fraction -= delta_y
      end
      next_y += step_y
      fraction += delta_x
      b_line << Vec2D.new(next_x, next_y)
    end
  end
  b_line
end

def draw
  background 255
  translate width / 2, height / 2
  rect_mode CENTER
  no_fill
  stroke 60
  (0..rows).each do |i|
    (0..cols).each do |j|
      rect((j - cols / 2) * N, (i - rows / 2) * N, N, N)
    end
  end
  x = mouse_x - width / 2 + N / 2
  y = mouse_y - height / 2 + N / 2
  b_line = build_line(from: Vec2D.new, to: Vec2D.new(x / N, y / N))
  unless b_line.empty?
    fill color('#C7B097')
    b_line.each { |v| rect(v.x * N, v.y * N, N, N) }
  end
  stroke color('#0000FF')
  stroke_width 2
  line 0, 0, mouse_x - width / 2, mouse_y - height / 2
  stroke 0
  stroke_width 1
end