Activity: Info Events

The ||info:Info|| category has three values that it can keep track of by default: a player’s ||info:score|| and ||info:health||, as well as a ||info:countdown|| for the game.

In addition to keeping track of those values, it also allows for a few interesting events: ||info:on life zero|| and ||info:on countdown end||. These events allow you to override the default behavior of ending the game when the values hit zero.

Concept: ||info:Life||, ||info:Score||, and ||info:Countdown||s

The values in the ||info:info|| can be modified using a few different methods.

Example #1a: Setting the Score (and Life)

1. Review the code below
2. Identify which sections are used to modify the ||info:score||
3. Identify which sections are used to modify the ||info:life||

info.setScore(0);
info.setLife(5);

controller.A.onEvent(ControllerButtonEvent.Pressed, function () {
    info.changeScoreBy(1);
});

controller.B.onEvent(ControllerButtonEvent.Pressed, function () {
    info.changeLifeBy(-1);
});

Example #1b: Counting Down

1. Review the code below
2. Identify which sections are used to create a ||info:countdown||
3. Identify how the game is played: what is the goal?

info.setScore(0);

controller.A.onEvent(ControllerButtonEvent.Pressed, function () {
    info.changeScoreBy(1);
});

info.startCountdown(15);

Student Task #1: Losing Life

1. Review the code below, and copy it into a new project
2. Set the ||info:life|| to 100 to start
3. Modify the ||sprites:Overlap|| event so that it will ||info:info.changeScoreBy|| -1 when the ||sprites:Player|| ||sprites:overlaps|| with the ||sprites:Enemy||
4. Challenge: currently, the ||sprites:overlap|| event will continue to take away life each ||game:game update|| where the ||sprites:sprites|| overlap. To fix this, make one of the ||sprites:sprites|| a ||sprites:Ghost||, ||loops:pause|| for 500 ms, and then turn off ||sprites:Ghost||, so that the ||sprites:overlap|| event will only trigger once every 500 ms

let mySprite = sprites.create(img`
    1 1 1
`, SpriteKind.Player);
controller.moveSprite(mySprite, 100, 100);

let enemy = sprites.create(img`
    5 2 5
    2 5 2
    5 2 5
`, SpriteKind.Enemy);
enemy.x += 50;

sprites.onOverlap(SpriteKind.Player, SpriteKind.Enemy, function (sprite: Sprite, otherSprite: Sprite) {
    sprite.say("ouch!", 250);
});

Concept: ||info:Info|| Events

By default, getting down to 0 ||info:lives|| or running out of time for a ||info:countdown|| causes a ||game:game over||. If a game requires a different behavior for this situation, then this behavior can be handled using one of two events: ||info:info.onLifeZero|| and ||info:info.onCountdownEnd||.

Example #2: Running out of Lives

1. Review the code below
2. Identify how the ||info:info.onLifeZero|| changes the behavior of the game

info.setScore(0);
info.setLife(5);

controller.A.onEvent(ControllerButtonEvent.Pressed, function () {
    info.changeScoreBy(1);
});

controller.B.onEvent(ControllerButtonEvent.Pressed, function () {
    info.changeLifeBy(-1);
});

info.onLifeZero(function () {
    if (game.ask("Do you want to continue?")) {
        info.setLife(5);
    } else {
        game.over();
    }
});

Student Task #2: Loss Animation

1. Start with the code from task #1
2. Add an ||info:on life zero|| event, which turns ||variables:mySprite|| into a ||sprites:Ghost||
3. Use ||game:game.splash|| to display “Oh no, I have lost…”
4. After the ||game:splash screen||, end the game with ||game:game.over||

Student Task #3: More Time!

1. Start with the code from task #2
2. Add a ||info:countdown|| that starts at 20 seconds
3. Add an ||info:on countdown end|| event
4. In the ||info:on countdown end|| event, make ||variables:mySprite|| ||sprites:say|| “Oops, I need more time!” for 1000 ms
5. In the ||info:on countdown end|| event, start a new ||info:countdown|| with 20 seconds

What did we learn?

1. How are the properties in the ||info:Info|| category different from the ||variables:Variables|| we create?
2. How do the ||info:Info|| events add more options to the games we create?

namespace overlapevents {
    // When the player hits an asteroid, damage the player and destroy the asteroid
    sprites.onOverlap(SpriteKind.Player, SpriteKind.Asteroid, function (sprite: Sprite, otherSprite: Sprite) {
        info.changeLifeBy(-1);
        otherSprite.destroy();
    });

    // When the player hits an enemy, damage the player and destroy the enemy
    sprites.onOverlap(SpriteKind.Player, SpriteKind.Enemy, function (sprite: Sprite, otherSprite: Sprite) {
        info.changeLifeBy(-1);
        otherSprite.destroy();
    });

    // When a laser hits an asteroid, destroy both sprites
    sprites.onOverlap(SpriteKind.Laser, SpriteKind.Asteroid, function (sprite: Sprite, otherSprite: Sprite) {
        info.changeScoreBy(1);
        otherSprite.destroy(effects.fire, 200);
        sprite.destroy();
    });

    // When a laser hits an enemy, destroy both sprites
    sprites.onOverlap(SpriteKind.Laser, SpriteKind.Enemy, function (sprite: Sprite, otherSprite: Sprite) {
        info.changeScoreBy(1);
        otherSprite.destroy(effects.bubbles);
        sprite.destroy();
    });

    // When an  enemy laser hits the player, destroy the laser, say "ow!", and lose life
    sprites.onOverlap(SpriteKind.Player, SpriteKind.EnemyLaser, function (sprite: Sprite, otherSprite: Sprite) {
        info.changeLifeBy(-1);
        otherSprite.destroy();
        sprite.say("ow!", 500);
    });
}

namespace status {
    info.onLifeZero(function () {
        let playerContinue = game.ask("Continue?", "Cost: 50 points");
        if (playerContinue) {
            info.setLife(3);
            info.changeScoreBy(-50);
        } else {
            game.over();
        }
    });
}