alexdantas · September 6, 2013 03:15 · Sep 6, 2013
diff --git a/pipes.rb b/pipes.rb
@@ -0,0 +1,284 @@
+#!/usr/bin/env ruby
+#
+# pipes.rb: Displays a nice animation on the terminal,
+#           based on an old screensaver.
+#
+# If you want to see some action, scroll to the bottom.
+# The main code is between "begin" and "end".
+#
+# This code uses Ruby and it's Curses module to display
+# characters on the terminal.
+#
+# I've tried to keep the code clean but it's a mess by
+# now. Hey, I was excited when coding, don't blame me.
+#
+# This code is DEFINITELY not Rubyish. Looks like a messed
+# up C/C++ cousing. Maybe that creepy uncle who shows up
+# at birthday parties.
+
+require 'curses' # Awesome terminal-handling library
+
+# Since Ruby doesn't natively supports "enums", I've
+# used a lot of labels (those things with ':')
+# If you find a better one, please tell me (eu@alexdantas.net)
+:direction_left
+:direction_right
+:direction_up
+:direction_down
+
+# Represents a single pipe, that will scroll around the
+# screen, leaving a colourful trail behind.
+class Pipe
+
+  # It's public components.
+  attr_reader :x, :y, :behaviour
+
+  # All possible colors that a pipe can have.
+  Colors = {
+    :black   => 1,
+    :white   => 2,
+    :red     => 3,
+    :yellow  => 4,
+    :magenta => 5,
+    :blue    => 6,
+    :green   => 7,
+    :cyan    => 8
+  }.freeze
+
+  # The possible ways a pipe can behave.
+  # Nice little feature, right?
+  Behaviour = [:dumb,  # Randomly decide where to go
+               :line,  # Keep making long lines
+               :curvy] # Make a lot of curves
+
+  # Constructor, creates a pipe.
+  def initialize(x, y, behaviour = :dumb, color = Colors[:cyan])
+    @x = x
+    @y = y
+    @appearance = '-'
+    @previous_dir = :direction_right
+    @current_dir = :direction_right
+    @color = Curses::color_pair color
+    @behaviour = behaviour
+  end
+
+  # Shows the pipe on the screen.
+  # This is VERY UGLY, DAMn.
+  def print
+
+    # If we're changing direction it's best to use '+' instead
+    # of '-' or '|'
+    if @current_dir == :direction_right or @current_dir == :direction_left
+      if (@previous_dir == :direction_up or @previous_dir == :direction_down)
+        @appearance = '+'
+      else
+        @appearance = '-'
+      end
+
+    elsif @current_dir == :direction_up or @current_dir == :direction_down
+      if (@previous_dir == :direction_left or @previous_dir == :direction_right)
+        @appearance = '+'
+      else
+        @appearance = '|'
+      end
+    end
+
+    Curses::setpos(@y, @x)
+    Curses::attrset @color
+    Curses::addstr @appearance
+    Curses::refresh
+  end
+
+  # Refreshes the pipe's direction.
+  # If `change_direction` is true, forces the pipe to
+  # do it.
+  # If not, it will keep on it's current way.
+  def refresh_direction(change_direction)
+
+    dir = @current_dir
+
+    if change_direction
+      begin
+        # Getting a random direction
+        result = Random.new.rand(1..4)
+
+        if    result == 1; dir = :direction_left
+        elsif result == 2; dir = :direction_up
+        elsif result == 3; dir = :direction_right
+        else               dir = :direction_down
+        end
+      end while not is_valid_movement? dir
+    end
+
+    @previous_dir = @current_dir
+    @current_dir = dir
+  end
+
+  # Tells if we can move the cursor to the next direction.
+  # Invalid movements will be returning 180o.
+  def is_valid_movement? dir
+    if (@current_dir == :direction_right and dir == :direction_left)  or
+       (@current_dir == :direction_left  and dir == :direction_right) or
+       (@current_dir == :direction_up    and dir == :direction_down)  or
+       (@current_dir == :direction_down  and dir == :direction_up)
+       return false
+    else
+      return true
+    end
+  end
+
+  # Actually steps the terminal a position on the screen,
+  # based on it's internal directions.
+  def move
+    if    @current_dir == :direction_right; @x += 1
+    elsif @current_dir == :direction_left;  @x -= 1
+    elsif @current_dir == :direction_up;    @y -= 1
+    elsif @current_dir == :direction_down;  @y += 1
+    end
+
+    out_of_screen = false
+
+    if @x < 0
+      @x = Curses::cols - 1
+      out_of_screen = true
+    elsif @x > Curses::cols - 1
+      @x = 0
+      out_of_screen = true
+    end
+
+    if @y < 0
+      @y = Curses::lines - 1
+      out_of_screen = true
+    elsif @y > Curses::lines - 1
+      @y = 0
+      out_of_screen = true
+    end
+
+    self.change_color if out_of_screen
+  end
+
+  # Randomly changes the pipe's color.
+  def change_color
+    result = Random.new.rand(Colors[:red]..Colors[:cyan]) # first..last
+    @color = Curses::color_pair result
+
+    # Randomly choosing between normal and bold
+    @color = @color | Curses::A_BOLD if random_bool
+  end
+
+  # Updates all the pipe's internal stuff.
+  def update
+    if @behaviour == :dumb
+      if random_bool
+        self.refresh_direction true
+      else
+        self.refresh_direction false
+      end
+
+    elsif @behaviour == :line
+      if random_bool_with_chance 0.2
+        self.refresh_direction true
+      else
+        self.refresh_direction false
+      end
+
+    elsif @behaviour == :curvy
+      if random_bool_with_chance 0.8
+        self.refresh_direction true
+      else
+        self.refresh_direction false
+      end
+    end
+
+    self.print
+    self.move
+  end
+end
+
+# Initializes the curses engine.
+# ugly function is ugly D:
+def curses_init timeout
+  Curses::init_screen
+  Curses::start_color
+  Curses::init_pair(Pipe::Colors[:black],   Curses::COLOR_BLACK,   Curses::COLOR_BLACK)
+  Curses::init_pair(Pipe::Colors[:white],   Curses::COLOR_WHITE,   Curses::COLOR_BLACK)
+  Curses::init_pair(Pipe::Colors[:red],     Curses::COLOR_RED,     Curses::COLOR_BLACK)
+  Curses::init_pair(Pipe::Colors[:yellow],  Curses::COLOR_YELLOW,  Curses::COLOR_BLACK)
+  Curses::init_pair(Pipe::Colors[:magenta], Curses::COLOR_MAGENTA, Curses::COLOR_BLACK)
+  Curses::init_pair(Pipe::Colors[:blue],    Curses::COLOR_BLUE,    Curses::COLOR_BLACK)
+  Curses::init_pair(Pipe::Colors[:green],   Curses::COLOR_GREEN,   Curses::COLOR_BLACK)
+  Curses::init_pair(Pipe::Colors[:cyan],    Curses::COLOR_CYAN,    Curses::COLOR_BLACK)
+  Curses::curs_set 0
+  Curses::noecho
+  Curses::nonl
+  Curses::timeout = timeout
+  Curses::refresh
+end
+
+# Returns randomly 'true' or 'false'.
+def random_bool
+  result = Random.new.rand(1..10)
+
+  if (result % 2) == 0 # is even
+    return true
+  else
+    return false
+  end
+end
+
+# Returns 'true' or 'false' with a probability of 'chance'
+def random_bool_with_chance chance
+  result = Random.new.rand(1..100)
+
+  return true if (result <= (chance*100))
+  return false
+end
+
+# Here's the main function!
+#                  _        _  __
+#                 (_)      /   \ \
+#  _ __ ___   __ _ _ _ __ | |   | |
+# | '_ ` _ \ / _` | | '_ \| |   | |
+# | | | | | | (_| | | | | | |   | |
+# |_| |_| |_|\__,_|_|_| |_| |   | |
+#                          \_  /_/
+begin
+  timeout = 50 # default delay in miliseconds
+
+  curses_init timeout
+
+  pipes = [Pipe.new(Curses::cols/2, Curses::lines/2, :dumb,  Pipe::Colors[:cyan]),
+           Pipe.new(Curses::cols/4, Curses::lines/8, :line,  Pipe::Colors[:red]),
+           Pipe.new(Curses::cols/8, Curses::lines/4, :curvy, Pipe::Colors[:magenta])]
+
+  while true
+    # Updating all pipes
+    for i in 0..(pipes.size-1)
+      pipes[i].update
+    end
+
+    # This is where the timeout delay happens.
+    case Curses::getch
+
+    when 'q', 'Q' # quit
+      break
+
+    when 'a', 'A' # faster!
+      timeout -= 10
+      timeout = 10 if timeout < 10
+      Curses::timeout = timeout
+
+    when 's', 'S' # slower!
+      timeout += 10
+      timeout = 50 if timeout > 50
+      Curses::timeout = timeout
+
+    when 'c', 'C' # clear
+      Curses::clear
+      Curses::refresh
+    end
+  end
+
+  exit 0
+end
+