Tutorials · Sound and Music · Chapter 11

Layers

A heartbeat

Layers

1. In Assets, double-click music/crypt.data to open it in the Inspector.
2. On 1 calm, press + beside Layers: a layer, 1, as a layer comes, at Volume 1. Type heartbeat in its Name, drop heartbeat.wav on its Clip, and set its Volume to 0.
3. On 2 danger, press + beside its Layers, empty too, and do the same: heartbeat, heartbeat.wav, Volume 0. Press Save.

A track’s Layers

Clips that play with the track, from its first sample and in step with it, each at its own level, a row each. A script turns one up and down by its name. A track with layers starts about a tenth of a second after it is asked for, so that every layer starts on the same sample as its track.

A layer’s Name

What set_music_layer calls it by. The level belongs to the name, not to the track: two tracks with a layer of the same name share its level, so the heartbeat keeps it as calm and danger change places.

A layer’s Clip

The sound the layer plays, in step with the track’s Clip. It must be as long as the track’s, or it drifts out of step as they loop; the Problems tab lists a layer that is not.

A layer’s Volume

How loud the layer starts, from 0, silent, to 1, as loud as the track. A new layer comes at 1. Here 0: the script turns it up.

An arrival

1. Press + beside Tracks: 5, a copy of caught, the row above, with Looping unticked. Name it arrival, drop crypt-calm.wav on its Clip and crypt-intro.wav on its Intro, and tick Looping.
2. On 1 calm, click its Intro slot and pick (none) to empty it. The Problems row goes.
3. Press + beside Rules: rule 7, a copy of rule 6, found to calm, AtEnd. Set its From to arrival. Press Save.
4. In the Levels tab, click The Crypt row and pick arrival in its Track list.

1. In Assets, click Assets in the path bar, so the script is written at the project’s top, then click Create, choose New script, type arrival and press Enter. Replace everything in arrival.rgs with the script below, and press Ctrl+S.
2. Select Crypt, the root, press Add component and choose Arrival. Press Ctrl+S.

/// The crypt's arrival. The crypt's level opens its music on the track
/// arrival: the intro, running into calm's tune, with no heartbeat under it.
/// As the crypt opens, this asks for calm, and the rule from arrival to calm
/// is At End: calm waits for the arrival's end, and comes in there, its
/// heartbeat with it, with no gap.
component Arrival {
    fn on_create() {
        play_music("calm");
    }
}

The heartbeat’s bands

1. In Assets, double-click ghost.rgs. Replace everything in it with the script below, and press Ctrl+S.
2. Select ghost: its Ghost now has Loudest 1, Swell 1 s and Heartbeat. Leave them.

/// The ghost, drifting its round through the flooded passage. Near the
/// knight it turns the crypt's music to danger, and once it is far from him
/// again, back to calm; and the nearer it comes, the louder the heartbeat
/// under the music. A knight its Area touches is caught: the music cuts to a
/// sting, and he is sent back to where he started, in the entrance hall.
component Ghost : Area {
    /// Where a knight the ghost touches is sent back to: his start in the
    /// entrance hall.
    back_to: Vec2,
    /// How near the knight the ghost turns the music to danger.
    #[suffix("u")]
    near: f32 = 64.0,
    /// How far from him it turns the music back to calm. Farther than near,
    /// so a ghost drifting along the edge does not turn it back and forth.
    #[suffix("u")]
    far: f32 = 96.0,
    /// Whether it has turned the music to danger, or to the sting that waits
    /// for calm, so that it asks for each change once and not on every step.
    #[readonly]
    close: bool = false,
    /// How loud the heartbeat beats with the ghost at its nearest: 1 is as
    /// loud as the music, 0 silent.
    loudest: f32 = 1.0,
    /// How long the heartbeat takes to swell or fall to a new level.
    #[suffix("s")]
    swell: f32 = 1.0,
    /// How loud it last asked the heartbeat to be, so that it asks once each
    /// time the knight crosses into another band, and not on every step.
    #[readonly]
    heartbeat: f32 = 0.0,

    fn loop() {
        let knight = nearest("knight");
        if knight != node(0) {
            let apart = position().distance(position_of(knight));
            // danger and calm are tracks of the crypt's music asset, the
            // level's Music: its rules say how one turns into the other.
            if !close && apart < near {
                play_music("danger");
                close = true;
            } else if close && apart > far {
                play_music("calm");
                close = false;
            }
            // The heartbeat is a layer of calm and of danger: silent beyond
            // 160, then a quarter, a half and all of loudest within 160, 96
            // and 48, each band twice as loud as the one outside it.
            let level = 0.0;
            if apart < 48.0 {
                level = loudest;
            } else if apart < 96.0 {
                level = loudest * 0.5;
            } else if apart < 160.0 {
                level = loudest * 0.25;
            }
            if level != heartbeat {
                // The level belongs to the layer's name, not to a track, so
                // the heartbeat keeps it as calm and danger change places.
                set_music_layer("heartbeat", level, swell);
                heartbeat = level;
            }
        }
    }

    fn on_enter(other: NodeId) {
        if in_group(other, "knight") {
            // The sting cuts in at once, whatever is playing.
            play_music("caught");
            // Still close: once he is far from the ghost, it asks for calm,
            // which waits for the sting's end.
            close = true;
            move_node(other, back_to);
        }
    }
}

set_music_layer

set_music_layer("heartbeat", level, swell) fades the layer named heartbeat to level, from 0 to 1, over swell seconds, on every track playing; the level is kept for any track that starts later with a layer of that name. Each ask starts its fade again from where the layer is.

Loudest, the ghost’s

How loud the heartbeat beats with the ghost at its nearest: 1 is as loud as the music, 0 silent. The bands are shares of it.

Swell, the ghost’s

How long the heartbeat takes to rise or fall to a new band’s level, in seconds.

Heartbeat, the ghost’s

The level it last asked for, so that it asks once each time the knight crosses into another band. #[readonly]: the script writes it. It is the level asked, not the level heard while the swell is on its way.

Heard

A layer’s row, in the Sound tab’s Music band

Under each track sounding, its layers: the level the layer is at, which set_music_layer moves, and what it is heard at, that level times its track’s gain in a crossfade. Halfway through, both heartbeats sound, each at its track’s share.

The crypt, exported

1. Press F5 again to stop, and save with File → Save all: Export copies the files as they are on disk.
2. Click the Build tab, in the dock under the Viewport.
3. In its Export section, the line under Export says where the game will be written, sound-and-music/dist/sound-and-music/sound-and-music: your project’s folder, then dist, then a folder and a file both named after it.
4. Press Export. When it is done, the editor opens the new folder in your file manager.
5. Double-click sound-and-music, or sound-and-music.exe on Windows. On Linux, if double-clicking does not start it, run ./sound-and-music in a terminal in that folder.

Who decides what you hear

The layers

Check it works