PICO-8 code

// == purpose functions ==

function ball_distx(box_x)
 return box_x-ball_x
end
function ball_disty(box_y)
 return box_y-ball_y
end
function inrange(num,min,max)
 if num >= min and num <= max then
  flip()
  return true
 else
  return false
 end
end

[ . . . ]

// == the update function ==

function _update60()
[ . . . ]
 // move the ball based on the set speed
 ball_x+=ball_dx*ball_speed
 ball_y+=ball_dy*ball_speed

 // if the ball is beyond the right/bottom of the screen...
 if ball_x>115 or ball_y>127
 // ...or the top/left...
 or ball_x<5 or ball_y<2
 then
  // reverse the direction
  ball_dx = -ball_dx
  ball_dy = -ball_dy
  ball_ang = rnd(4)
  // play the ball hit sound sound
 end

// ball collision
 if ball_disty(110) == 0 and ball_distx(pad_x) >= -4 and ball_distx(pad_x) <= 4 then
  // context: pad_dir is the direction the paddle is facing, which is controlled either by the Z and X buttons or by what direction the paddle is moving in
  if pad_dir == 0 then
   ball_dx = -1
   ball_dy = -1
  end
  if pad_dir == 1 then
   ball_dx = 0
   ball_dy = -1
  end
  if pad_dir == 2 then
   ball_dx = 1
   ball_dy = -1
  end
  //ball_speed += .1
 end
end

// == the draw function ==

function _draw()
 // clear the screen
 cls()
 // print any test variables
 print(ball_distx(pad_x),20,0,7)
 print(ball_disty(110),50,0,7)

[ . . . ]

// draw the ball
 spr(ball_spr,ball_x,ball_y)

 // draw the paddle
 spr(pad_spr,pad_x,110)
 // ball animation
 mn = ball_disty(110)
 if inrange(ball_distx(pad_x),-4,4) then
  if inrange(mn,-1,1) then ball_spr = pad_spr end
  if inrange(mn,-2,2) then ball_spr = 18 end
  if inrange(mn,-3,3) then ball_spr = 17 end
  if inrange(mn,-4,4) then ball_spr = 0 end
 else
  if ball_x==112 or ball_x==8 then flip() flip() ball_spr=0 end
  if ball_x==113 or ball_x==7 then flip() flip() ball_spr=1 end
  if ball_x==114 or ball_x==6 then flip() flip() ball_spr=2 end
  if ball_x==115 or ball_x==5 then flip() flip() ball_spr=3 end
 end
end