Effects and sound

/// A puff of particles: its Particle Emitter fires once as it arrives, and its
/// Audio Source plays if it has one, with nothing here to call; once its last
/// particle has died it removes itself.
component Puff {
    /// Seconds it stays: longer than its particles live.
    #[suffix("s")]
    lifetime: f32 = 1.0,

    fn on_create() {
        await wait(lifetime);
        destroy_self();
    }
}

/// The knight's footfall: as its body lands, dust puffs up at its feet from
/// the knight's Spawner, and its Audio Source plays the landing.
component Footfall : Body {
    fn on_land() {
        spawn("dust", position());
        play_sound("land");
    }
}

/// With no hearts left, the level is lost. Each step it keeps where it is,
/// for the beast to aim at. Its jump, slash, hit and hurt are sounds its Audio
/// Source names; its landing is its Footfall's.

        if heard("recoil") {
            play_sound("hit");
            set_number("CharacterBodyComponent", "velocity.x", -facing * recoil_speed);
            hopping = recoil_time;
        }

            if pressed("jump") && !drop {
                jump();
                // A jump from the ground, or the second in the air, sounds.
                if grounded() || kept_number("double_jump", 0.0) > 0.0 {
                    play_sound("jump");
                }
            }

        if pressed("attack") && kept_number("sword", 0.0) > 0.0 && readying <= 0.0 && hurting <= 0.0 {
            play_clip("slash");
            shown = "slash";
            slashing = slash_time;
            readying = cooldown;
            play_sound("slash");
        }

                // The hurt clip plays over whatever the knight was doing.
                hurting = hurt_time;
                play_sound("hurt");

/// A heart lying in the crypt: it bobs, and the knight takes it by walking
/// into it, which heals one heart. Then it is gone in a sparkle.
component Heart : Area {
    fn on_create() {
        pulse_by(vec2(0.0, -3.0), 0.5, .InOutSine);
    }

    fn on_enter(other: NodeId) {
        if in_group(other, "knight") {
            // The knight is in the group "knight", and hears this a step
            // later.
            emit_to("knight", "heal");
            // A sparkle from this node's Spawner, which carries the pickup's
            // sound.
            spawn("sparkle", position());
            hide();
        }
    }
}

/// A relic on an altar: it glows, and the knight takes it by walking into it.
/// Taking it keeps 1 under `power` for the rest of the game, and the relic is
/// gone in a sparkle.
component Relic : Area {
    /// The kept value that taking it sets to 1.
    power: String = "double_jump",

    fn on_create() {
        pulse_colour("ShapeComponent", "color", vec4(1.0, 1.0, 1.0, 0.4), 0.6, .InOutSine);
    }

    fn on_enter(other: NodeId) {
        if in_group(other, "knight") {
            keep_number(power, 1.0);
            // A sparkle from this node's Spawner, which carries the pickup's
            // sound.
            spawn("sparkle", position());
            // A hidden Area meets nothing, so it cannot be taken twice.
            hide();
        }
    }
}

/// A creature the knight's sword can strike: a slash that lands on it flashes
/// it white and pushes the knight back.
component Struck : Area {
    fn on_enter(other: NodeId) {
        if in_group(other, "slash") {
            // The knight is in the group "knight", and is pushed back a step
            // later.
            emit_to("knight", "recoil");
            // The hit flash: white, there and gone.
            await anneal_number("SpriteComponent", "flash", 1.0, 0.04, .Linear);
            anneal_number("SpriteComponent", "flash", 0.0, 0.12, .OutQuad);
        }
    }
}

/// three fireballs at once. Its health is its Wounds', kept as `boss_hp`. It
/// roars as it wakes, and its slam and its fire are sounds its Audio Source
/// names.

    fn loop() {
        if !awake {
            // The arena sends "begin" when the knight walks in.
            await signal("begin");
            awake = true;
            play_sound("roar");
            await wait(1.0);
        }

            // The wind-up: it glows red, unless it was slain while it rested.
            if kept_number("boss_hp", full) > 0.0 {
                pulse_colour("SpriteComponent", "color", vec4(1.0, 0.4, 0.4, 1.0), 0.1, .Linear);
            }
            await wait(windup * calm);

                    await wait_until(grounded());
                    set_number("CharacterBodyComponent", "velocity.x", 0.0);
                    // The camera's node is in the group "camera".
                    play_sound("slam");
                    emit_to("camera", "shake");

                        spawn("fireball", mouth + vec2(aim.x * c + aim.y * s, aim.y * c - aim.x * s) * 8.0);
                    }
                    play_sound("fireball");
                    await wait(0.3);

/// The beast's wounds: each slash of the knight's that lands takes one of its
/// health, flashes it white and pushes the knight back. Its health is kept as
/// `boss_hp`, which the boss bar shows and the beast's fury reads. At none it
/// is slain: it stops, hurts nothing more, flashes, bursts and roars, fades
/// away, and a moment later the level is won.
component Wounds : Area {
    /// How many slashes it takes to slay.
    health: f32 = 20.0,
    /// Seconds from the last slash to the level won.
    #[suffix("s")]
    dying_time: f32 = 2.0,

    fn on_create() {
        keep_number("boss_hp", health);
    }

    fn on_enter(other: NodeId) {
        if in_group(other, "slash") && health > 0.0 {
            health -= 1.0;
            keep_number("boss_hp", health);
            // The knight is in the group "knight", and is pushed back a step
            // later.
            emit_to("knight", "recoil");
            if health <= 0.0 {
                // It stops where it is, and its Area is on no layer the
                // knight's looks for.
                set_number("CharacterBodyComponent", "velocity.x", 0.0);
                set_number("AreaComponent", "layer", 0.0);
                // The big flash, a burst from its Spawner, and its roar.
                set_number("SpriteComponent", "flash", 1.0);
                spawn("burst", position() + vec2(0.0, -40.0));
                play_sound("roar");
                // It fades from white to nothing as the level ends.
                anneal_colour("SpriteComponent", "color", vec4(1.0, 1.0, 1.0, 0.0), dying_time, .InQuad);
                await wait(dying_time);
                complete();
            } else {
                // The hit flash: white, there and gone.
                await anneal_number("SpriteComponent", "flash", 1.0, 0.04, .Linear);
                anneal_number("SpriteComponent", "flash", 0.0, 0.12, .OutQuad);
            }
        }
    }
}

/// The arena's threshold: the first time the knight walks in, it sends
/// "begin" to the group "arena", which drops the portcullis behind the knight,
/// turns the camera onto the arena, shows the boss bar and wakes the beast;
/// and the boss loop takes over from the castle loop.
component Arena : Area {
    /// Whether the fight has begun, so it begins once.
    #[hidden]
    begun: bool = false,

    fn on_enter(other: NodeId) {
        if in_group(other, "knight") && !begun {
            begun = true;
            emit_to("arena", "begin");
            // The track this node's Audio Source names "boss", on the one
            // music channel.
            play_music("boss");
        }
    }
}