From: Bill Kelly <billk@...>
Date: 2008-06-16T05:30:29+09:00
Subject: Re: [QUIZ][SOLUTION] Circle Drawing (#166)

My solution follows....

Regards,

Bill


# Ruby Quiz #166
#
# This draws a circle of the specified radius, modified
# by an optional aspect ratio and thickness factor.
#
# implementation notes:
#   - for the fun of it, i forbade use of sqrt() and trancendentals
#   - the circle is not drawn into a buffer before being printed
#   - some values are empirically derived (thickness factor, in parciular)
#
# bugs:
#   - the thickness factor causes bloat in small circles

ARGV.length >= 1 or abort("usage: #$0 radius [aspect] [thickness]")

radius = ARGV.shift.to_f
radius > 0 or abort("please provide radius of circle")

aspect = ARGV.shift.to_f
aspect > 0 or aspect = 1.0

thick = ARGV.shift.to_f
thick > 0 or thick = 1.0

hradius = (radius * aspect).ceil + (thick/2.0).round
vradius = radius.ceil + (thick/2.0).round

def get_radius_ch(rsq, dsq, tfactor)
  (rsq - dsq).abs <= tfactor ? "*" : " "
end

tfactor = (thick * 4.0) + 2.5
rsq = radius**2
(-vradius).upto(vradius) do |y|
  (-hradius).upto(hradius) do |x|
    print(get_radius_ch(rsq, (x * (1.0/aspect))**2 + y**2, tfactor))
  end
  puts
end


# example: radius 7.0, aspect 1.0, thickness 1.0
#
# $ ruby 166_circle.rb 7 1 1
# 
#       *****
#     **     **
#    *         *
#   *           *
#   *           *
#  *             *
#  *             *
#  *             *
#  *             *
#  *             *
#   *           *
#   *           *
#    *         *
#     **     **
#       *****
#
#
# example: radius 10.0, aspect 2.0, thickness 5.0
#
# $ ruby 166_circle.rb 10 2 5
# 
# 
#                     *****
#              *******************
#           *************************
#        ********               ********
#      *******                     *******
#     ******                         ******
#    *****                             *****
#   *****                               *****
#  *****                                 *****
#  ****                                   ****
# *****                                   *****
# *****                                   *****
# *****                                   *****
#  ****                                   ****
#  *****                                 *****
#   *****                               *****
#    *****                             *****
#     ******                         ******
#      *******                     *******
#        ********               ********
#           *************************
#              *******************
#                     *****
#