expert_pong.rb

# frozen_string_literal: true

#
# Pong in Shoes
# a clone of http://billmill.org/pong.html
# and shoes is at http://shoooes.net
#
# This is just for kicks -- I'm very fond of NodeBox as well.
#
# There's a slightly different approach in Shoes: rather than
# redrawing the shapes, you can move the shapes around as objects.
# Yeah, see, notice how @you, @comp and @ball are used.
#
Shoes.app width: 400, height: 400, resizable: false do
  paddle_size   = 75
  ball_diameter = 20
  vx = 3
  vy = 4
  compuspeed    = 10
  bounce        = 1.2

  # set up the playing board
  nostroke && background(white)
  @ball = oval 0, 0, ball_diameter, fill: "#9B7"
  @you, @comp = [app.height - 4, 0].map { |y| rect 0, y, paddle_size, 4, curve: 2 }

  # animates at 40 frames per second
  @anim = animate 40 do
    # check for game over
    if (@ball.top + ball_diameter).negative? || @ball.top > app.height
      para strong("GAME OVER", size: 32), "\n",
           @ball.top.negative? ? "You win!" : "Computer wins", top: 140, align: 'center'
      @ball.hide && @anim.stop
    end

    # move the @you paddle, following the mouse
    @you.left = mouse[1] - (paddle_size / 2)
    nx = (@ball.left + vx).to_i
    ny = (@ball.top + vy).to_i

    # move the @comp paddle, speed based on `compuspeed` variable
    @comp.left +=
      if nx + (ball_diameter / 2) > @comp.left + paddle_size
        compuspeed
      elsif nx < @comp.left
        -compuspeed
      else 0
      end

    # if the @you paddle hits the ball
    if ny + ball_diameter > app.height && vy.positive? &&
       (0..paddle_size).cover?(nx + (ball_diameter / 2) - @you.left)
      vx = (nx - @you.left - (paddle_size / 2)) * 0.25
      vy = -vy * bounce
      ny = app.height - ball_diameter
    end

    # if the @comp paddle hits the ball
    if ny.negative? && vy.negative? &&
       (0..paddle_size).cover?(nx + (ball_diameter / 2) - @comp.left)
      vx = (nx - @comp.left - (paddle_size / 2)) * 0.25
      vy = -vy * bounce
      ny = 0
    elsif nx + ball_diameter > app.width || nx.negative?
      vx = -vx
    end

    @ball.move nx, ny
  end
end