Penalty Shootout IV

Review — where we got to 5 min

• The keeper rolls (pick random (1) to (3)) into dive and glides to that side.
• The verdict asks <touching [Goalie v]?> first, then the goal test.
• The Referee sets the match up, broadcasts kick off, and reads the score at the end.

Quick-fire

You aim at the left corner every time. How often does last lesson’s keeper dive left?

Today’s Topic 3 min

• A keeper whose skill grows every kick
• A streak, and a best streak the green flag never resets
• Sudden death when the match is level
• A start screen with a PLAY button

Learning outcome

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

1. Use pick random and a comparison to make something happen “sometimes”.
2. Keep a record in a variable that no script resets.
3. Add an extra round when a game ends level.

Learnt — finishing the game 27 min

1 · A keeper who gets better

A real keeper watches the kicker and sometimes reads the shot. Ours reads it (keeper skill) times in every 100. The skill starts at 20 and rises by 10 each kick.

First the keeper works out which third the shot is going to:

Then it rolls a number from 1 to 100. If the roll is under the skill, it dives the right way. If not, it guesses like before.

if <(pick random (1) to (100)) < (20)> then
              

if <(pick random (1) to (100)) < (70)> then
              

1. Make shot side and keeper skill, For all sprites.
2. Change the old dive script’s hat to when I receive [dive v]. Remove its set [dive v] to (pick random (1) to (3)).
3. Build a new “think” script on when I receive [kick v]. It ends with broadcast [dive v] and wait.
4. Add when I receive [start match v] with set [keeper skill v] to (20).

when I receive [kick v]
set [shot side v] to (2)
if <(aim x) < (-33)> then
  set [shot side v] to (1)
end
if <(aim x) > (33)> then
  set [shot side v] to (3)
end
if <(pick random (1) to (100)) < (keeper skill)> then
  set [dive v] to (shot side)
else
  set [dive v] to (pick random (1) to (3))
end
change [keeper skill v] by (10)
broadcast [dive v] and wait
              

when I receive [dive v]
if <(dive) = (1)> then
  switch costume to [goalie-c v]
  glide (0.4) secs to x: (-62) y: (10)
end
if <(dive) = (2)> then
  switch costume to [goalie-e v]
  glide (0.4) secs to x: (0) y: (10)
end
if <(dive) = (3)> then
  switch costume to [goalie-d v]
  glide (0.4) secs to x: (62) y: (10)
end
wait (1.2) seconds
switch costume to [goalie-a v]
go to x: (0) y: (10)
              

2 · A streak, and a best streak

(streak) counts goals in a row. A save or a miss puts it back to 0. (best streak) is the highest streak ever.

when I receive [judge v]
if <touching [Goalie v]?> then
  say [Saved!] for (1) seconds
  set [streak v] to (0)
else
  if <<<(aim x) > (-100)> and <(aim x) < (100)>> and <<(aim y) > (-25)> and <(aim y) < (85)>>> then
    change [goals v] by (1)
    change [streak v] by (1)
    if <(streak) > (best streak)> then
      set [best streak v] to (streak)
    end
    say [GOAL!] for (1) seconds
  else
    say [Miss!] for (1) seconds
    set [streak v] to (0)
  end
end
change [kicks left v] by (-1)
            

And one tiny script on the Ball: when I receive [start match v] then set [streak v] to (0). Look for the script that sets best streak to 0. There is none, on purpose.

3 · Sudden death

The other team has already taken their kicks. At the start, the Referee picks their score: (pick random (2) to (4)). Beat it to win.

1. Make their goals. Show its box on the Stage.
2. After five kicks, the Referee compares the scores.
3. Level? Set kicks left to 1 and broadcast kick off again. That is sudden death: one kick, and it decides.
4. Then more goals wins. Anything else loses.

when I receive [start match v]
set [goals v] to (0)
set [kicks left v] to (5)
set [their goals v] to (pick random (2) to (4))
broadcast [kick off v]
wait until <(kicks left) = (0)>
if <(goals) = (their goals)> then
  set [kicks left v] to (1)
  broadcast [kick off v]
  say [Sudden death! Score to win.] for (2) seconds
  wait until <(kicks left) = (0)>
end
if <(goals) > (their goals)> then
  say [You win the shootout!]
else
  say [They win this time.]
end
            

4 · A start screen

A game should wait for the player. Two new sprites do it: a title, and a PLAY button.

when flag clicked
go to x: (0) y: (-60)
go to [front v] layer
show

when this sprite clicked
hide
broadcast [start match v]
              

when flag clicked
go to x: (0) y: (130)
show

when I receive [start match v]
hide
              

Now the match starts on start match, not the flag. The Referee’s hat changes to when I receive [start match v].

The Aim marker needs one change too:

when flag clicked
hide

when I receive [start match v]
set size to (70) %
go to [front v] layer
show
forever
  go to [mouse-pointer v]
end
            

Basic — finish the game 25 min

Open last lesson’s project. Save a copy first, so you can always go back.

Step 1 — the keeper learns

1. Make shot side and keeper skill.
2. Split the keeper into think and dive, as in Learnt 1.
3. Add the start match script that sets the skill to 20.

Step 2 — the streak

1. Make streak and best streak. Show best streak.
2. Update the Ball’s verdict from Learnt 2.
3. Add when I receive [start match v] and set [streak v] to (0) on the Ball.

Step 3 — sudden death

1. Make their goals. Show it.
2. Rebuild the Referee’s script from Learnt 3.

Step 4 — the start screen

1. Paint a title sprite and a PLAY button sprite. Words in big, clear letters.
2. Give them the scripts from Learnt 4.
3. Hide the Aim until start match.

Step 5 — who starts on the flag?

Only these should run on the green flag now:

• the title and PLAY showing,
• the Aim hiding,
• the keeper, the ball and the Referee going to their places.

Everything else waits for start match or kick off.

Step 6 — play three matches

Write down each result and your best streak after each one.

A keeper who learns

• The keeper’s skill starts low at the start of every match.
• It rises after every kick.
• A high skill means the keeper dives the right way more often.
• It still guesses wrong sometimes, even at the end.

A record that lasts

• streak counts goals in a row, and resets on a save or a miss.
• best streak keeps the highest streak ever.
• The green flag does not reset best streak.
• Saving and reopening the project does not reset it either.

An ending

• A start screen waits for PLAY.
• The other team’s score is chosen at random, 2 to 4, and shown.
• After five kicks, more goals win and fewer lose.
• Level means one sudden-death kick, and that kick decides.

They kick too

In a real shootout the teams take turns. Make the other team take a kick after each of yours — and end the match early when one side cannot catch up.

if <((goals) + (kicks left)) < (their goals)> then
  say [They cannot be caught.] for (2) seconds
end
              

Summary 3 min

• <(pick random (1) to (100)) < (keeper skill)>is true about “keeper skill” times in 100.
• A script that works can keep its job. Give it a new hat instead of rewriting it.
• A record lasts as long as nothing resets it. Scratch saves it with the project.
• A tie can be broken with one more round: the same loop, started again.
• A start screen is a button that broadcasts, and scripts that wait for it.

Skill

How often the keeper reads the shot, out of 100.

Streak

Goals in a row, with no save or miss between.

Record

The best so far. Only beaten, never reset.

Sudden death

One more kick when it is level. That kick decides.

Ship it

Four lessons ago you pointed at a goal and clicked. Now you have a meter, a keeper who learns, a referee and a record. Play it cold: save, do something else for ten minutes, then play it following only what is on the screen. Fix anything that confused you.

If you have a Scratch account, share it on the Scratch website and send the link to your teacher.