Brick Breaker IV

Review — Brick Breaker III 5 min

• The offset — ball x minus paddle x — set vx, so the player could aim.
• Speed grew by 0.5 a hit, but never past 8: a ball faster than the paddle is unfair.
• A miss put the speed back to 5, and serve sent the ball straight up.

Quick-fire

In Bubble Popper (Level 3) twenty bubbles each floated at their own speed. What did each bubble need, that one shared speed variable could not give it?

Today’s Topic 3 min

• Power-ups from a list: wide, slow, multi
• Many balls as clones, each with its own vx and vy
• Juice: sparks and a shake
• Levels from save codes, and a win

Learning outcome

By the end of this lesson you will be able to:

1. Drop a power-up chosen from a list, and give it an effect.
2. Run many copies of one object, each keeping its own numbers.
3. Move from level to level and end the game with a win.

Learnt — power-ups, polish and levels 28 min

1 · A ? brick drops a capsule

A new letter, ?, is a gold brick that breaks in one hit and drops a capsule. Which capsule? The next one in a list called power-ups.

The list works like a bag: take the next one, and start again at the end. So every power comes round in turn — no three slows in a row.

define drop
change [turn v] by (1)
if <(turn) > (length of [power-ups v])> then
  set [turn v] to (1)
end
set [next power v] to (item (turn) of [power-ups v])
set [drop x v] to ((-220) + ((40) * ((col) - (1))))
set [drop y v] to ((130) - ((20) * ((row) - (1))))
create clone of [Capsule v]
              

define hit brick
if <not <(tile) = [#]>> then
  change [score v] by (10)
  if <(tile) = [1]> then
    write [.] :: custom
    change [bricks left v] by (-1)
  else
    if <(tile) = [?]> then
      write [.] :: custom
      change [bricks left v] by (-1)
      drop :: custom
    else
      write ((tile) - (1)) :: custom
    end
  end
end
              

when I start as a clone
set [my power v] to (next power)
switch costume to (my power)
go to x: (drop x) y: (drop y)
show
repeat until <(y position) < (-170)>
  change y by (-3)
  if <touching [Paddle v]?> then
    set [power v] to (my power)
    broadcast [power up v]
    delete this clone
  end
end
delete this clone
            

2 · What each power does

Every power listens for power up and checks power. Wide belongs to the Paddle. It is timed with the timer, like Arena Duel’s cooldown — never by counting loops.

when I receive [power up v]
if <(power) = [wide]> then
  set size to (150) %
  set [wide until v] to ((timer) + (8))
end
            

Multi needs more than one ball — and three balls cannot share one vx. So the ball changes in two ways:

1. Delete vx and vy, and make them again for this sprite only. Now every clone has its own pair.
2. The original Ball hides and never plays. On serve it makes one clone. Every ball in the game is a clone.
3. balls counts them. A ball that falls deletes itself, and only the last one costs a life.

when I receive [serve v]
set [balls v] to (1)
go to x: (paddle x) y: (-128)
set [vx v] to (2)
set [vy v] to (5)
create clone of [myself v]

when I receive [power up v]
if <<(power) = [multi]> and <(is clone) = (0)>> then
  set [vx v] to (-4)
  set [vy v] to (5)
  create clone of [myself v]
  set [vx v] to (4)
  create clone of [myself v]
  change [balls v] by (2)
end
              

when I start as a clone
set [is clone v] to (1)
show
repeat (15)
  go to x: (paddle x) y: (-128)
end
forever
  move ball :: custom
  walls :: custom
  ... Lesson 31's paddle hit :: grey
  if <(y position) < (-170)> then
    change [balls v] by (-1)
    if <(balls) = (0)> then
      broadcast [lost v]
    end
    delete this clone
  end
end
              

Slow is on the Ball too. It needs no is clone check: every ball should slow down.

when I receive [power up v]
if <(power) = [slow]> then
  set [speed v] to (4)
  set [vx v] to ((vx) * (0.6))
  set [vy v] to ((vy) * (0.6))
end
            

3 · Juice: sparks and a shake

Juice is everything that makes a hit feel good but changes no rule. Two tricks:

when I start as a clone
go to x: (spark x) y: (spark y)
point in direction (pick random (-180) to (180))
show
repeat (10)
  move (4) steps
  change [ghost v] effect by (10)
end
delete this clone
              

when I receive [shake v]
repeat (8)
  set [shake x v] to (pick random (-4) to (4))
  set [shake y v] to (pick random (-3) to (3))
  wait (0.03) seconds
end
set [shake x v] to (0)
set [shake y v] to (0)
              

The Stage itself cannot move. So each brick adds the wobble to its own spot, at the end of its forever loop:

go to x: (((-220) + ((40) * ((my col) - (1)))) + (shake x)) y: (((130) - ((20) * ((my row) - (1)))) + (shake y))
            

In hit brick, after change [bricks left v] by (-1) (in both places), add:

set [spark x v] to (x position)
set [spark y v] to (y position)
repeat (6)
  create clone of [Spark v]
end
broadcast [shake v]
            

4 · Levels, and a win

Each level is a 72-letter save code — Lesson 30’s Extra — in a list called levels. unpack turns code number level into the wall.

1. The Brick builds on a broadcast now: build. Old clones hear it too, so they delete themselves first. Only the original (is clone = 0) builds.
2. A Referee sprite waits until bricks left is 0, and sends next level.
3. The Brick adds 1 to level. Past the last level, it sends win.

when I receive [build v]
if <(is clone) = (1)> then
  delete this clone
else
  build wall :: custom
  broadcast [serve v]
end

when I receive [next level v]
if <(is clone) = (0)> then
  change [level v] by (1)
  if <(level) > (length of [levels v])> then
    broadcast [win v]
  else
    set [code v] to (item (level) of [levels v])
    unpack :: custom
    broadcast [build v]
  end
end
              

when flag clicked
forever
  wait until <<(bricks left) = (0)> and <(score) > (0)>>
  broadcast [next level v]
  wait until <(bricks left) > (0)>
end

when I receive [win v]
say (join [You win! Score ] (join (score) [.]))
              

Basic — the whole game 25 min

Open your Brick Breaker III project. This is a big build, so tick each step off.

Step 1 — new lists and variables

1. Lists for all sprites: power-ups (wide, slow, multi) and levels.
2. Add three codes to levels, one for each wall below — the six rows joined into one 72-letter code.
3. Variables for all sprites: balls, turn, power, next power, drop x, drop y, wide until, shake x, shake y, spark x, spark y, level, code.

............
............
..?11??11?..
..22222222..
............
............

............
.33......33.
.2?2....2?2.
.111.##.111.
............
............

3..3..3..3..
.22.22.22.22
?11?11?11?11
............
#..........#
............

Step 2 — the sprites

1. Brick: add # and ? costumes and an is clone variable (this sprite only). Its green flag hides, sets is clone to 0 and level to 1, unpacks level 1 and sends build. Add the two scripts from Learnt section 4, and the shake to its clone loop.
2. Ball: remake vx and vy for this sprite only, add is clone, and build the serve, multi, slow and clone scripts from Learnt section 2. Add drop and the new hit brick.
3. Paddle: add the wide script and its timer check.
4. Capsule, Spark, Shaker: new sprites, all hidden on the green flag.
5. Referee: a heart in the corner. Its green flag sets lives to 3 and score to 0.

Step 3 — losing a life, and the end

when I receive [lost v]
change [lives v] by (-1)
if <(lives) = (0)> then
  broadcast [game over v]
else
  set [speed v] to (5)
  broadcast [serve v]
end
            

Surprise drops

The bag is fair, but players learn it. Add some surprise.

• The power is picked at random from the list.
• Any green brick that breaks has a 1-in-5 chance to drop one too.
• ? bricks still always drop.

set [next power v] to (item (pick random (1) to (length of [power-ups v])) of [power-ups v])
            

if <(pick random (1) to (5)) = (1)> then
  drop :: custom
end
            

A timer bar

A player cannot see when wide will run out. Draw it.

• While the paddle is wide, an orange bar sits along the bottom of the Stage.
• It starts 200 long and shrinks to nothing in 8 seconds.
• It is drawn with the Pen, not made of sprites.

when flag clicked
hide
erase all
set pen size to (5)
forever
  erase all
  if <(wide until) > (0)> then
    set pen color to [#F97316]
    go to x: (-100) y: (-172)
    pen down
    go to x: ((-100) + ((200) * (((wide until) - (timer)) / (8)))) y: (-172)
    pen up
  end
  wait (0) seconds
end
            

A catch power

Add a fourth power: catch.

• A green catch capsule. Add it to the list and to the Capsule’s costumes.
• After it, the next ball that hits the paddle sticks there.
• It rides the paddle until the space bar, then flies off with its aimed vx.

if <<(catching) = (1)> and <<touching [Paddle v]?> and <(vy) > (0)>>> then
  repeat until <key (space v) pressed?>
    go to x: (paddle x) y: (-128)
  end
  set [catching v] to (0)
end
            

A level editor

Tile Maker had a click-to-paint editor. Give Brick Breaker one.

• The game starts with an empty wall and a cursor that snaps to the cell under the mouse.
• A click changes that cell’s letter: . → 1 → 2 → 3 → # → ? → .
• The wall redraws straight away. Space starts the game on your level.

when flag clicked
show
go to [front v] layer
set [editing v] to (1)
forever
  brick at (mouse x) (mouse y) :: custom
  if <<(row) > (0)> and <(row) < (7)>> then
    go to x: ((-220) + ((40) * ((col) - (1)))) y: ((130) - ((20) * ((row) - (1))))
    if <<mouse down?> and <(editing) = (1)>> then
      set [next v] to (item (((item # of (tile) in [palette v]) mod (6)) + (1)) of [palette v])
      write (next) :: custom
      broadcast [build v]
      wait until <not <mouse down?>>
    end
  end
end

when [space v] key pressed
if <(editing) = (1)> then
  set [editing v] to (0)
  hide
  broadcast [serve v]
end
            

Summary 5 min

• A ? brick drops the next power from a list. A capsule clone carries it down.
• Many balls means clones, and vx and vy for this sprite only.
• Juice — sparks and shake — changes how a game feels, not its rules.
• Levels are save codes in a list. Clear the last one and you win.

Power-up

Something you collect that changes the rules for a while.

Juice

Effects that make actions feel good without changing the rules.

Bag

A list you take items from in turn, so each one comes round.

Hand in

Save your Brick Breaker — the arc is finished. Next lesson, a new arcade game: Kart Racer, where the car turns with sine and cosine.