Module: Bresenham::Circle

Defined in:
lib/bresenham/circle.rb

Class Method Summary collapse

Class Method Details

.coordinates(xm, ym, radius) ⇒ Object 



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# File 'lib/bresenham/circle.rb', line 3

def self.coordinates(xm, ym, radius)
  x = -radius
  y = 0
  err = 2-2*radius
  coords = Set.new

  begin
    coords << [xm + x, ym - y]
    coords << [xm - x, ym + y]
    coords << [xm + y, ym + x]
    coords << [xm - y, ym - x]
    radius = err
    if radius <= y
      y += 1
      err += y * 2 + 1
    end
    if radius > x or err > y
      x += 1
      err += x * 2 + 1
    end
  end while (x < 0)
  coords
end

.coordinates2(x0, y0, r) ⇒ Object 



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# File 'lib/bresenham/circle.rb', line 27

def self.coordinates2(x0, y0, r)
  p = 3 - 2 * r
  x = 0
  y = r
  coords = Set.new

  while (y >= x)
    coords << [x0 + x, y0 + y]
    coords << [x0 + x, y0 - y]
    coords << [x0 - x, y0 + y]
    coords << [x0 - x, y0 - y]
    coords << [x0 + y, y0 + x]
    coords << [x0 + y, y0 - x]
    coords << [x0 - y, y0 + x]
    coords << [x0 - y, y0 - x]
    if (p < 0)
      p += 4*x + 6
      x += 1
    else
      p += 4*(x - y) + 10
      x += 1
      y -= 1
    end
  end
  coords
end

.midpoint_algorithm(x0, y0, radius) ⇒ Object 



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# File 'lib/bresenham/circle.rb', line 54

def self.midpoint_algorithm(x0, y0, radius)
  f = 1 - radius
  ddF_x = 1
  ddF_y = -2 * radius
  x = 0
  y = radius
  coords = Set.new

  coords << [x0, y0 + radius]
  coords << [x0, y0 - radius]
  coords << [x0 + radius, y0]
  coords << [x0 - radius, y0]

  while x < y
    if f >= 0
      y -= 1
      ddF_y += 2
      f += ddF_y
    end
    x += 1
    ddF_x += 2;
    f += ddF_x;    
    coords << [x0 + x, y0 + y]
    coords << [x0 - x, y0 + y]
    coords << [x0 + x, y0 - y]
    coords << [x0 - x, y0 - y]
    coords << [x0 + y, y0 + x]
    coords << [x0 - y, y0 + x]
    coords << [x0 + y, y0 - x]
    coords << [x0 - y, y0 - x]
  end
  coords
end