# Scripting

Steps are programmed using Rhai, a simple scripting language.

## Basic Syntax

Create sounds using `sound()` and chain parameters:

```
sound("kick").gain(0.8)
```

```
sound("hat").freq(8000).decay(0.1)
```

## Context Variables

These are available in every step script:

- `step`: Current step index (0-based)
- `beat`: Current beat position
- `bank`: Current bank index
- `pattern`: Current pattern index
- `tempo`: Current BPM
- `phase`: Phase within the bar (0.0 to 1.0)
- `slot`: Slot number playing this pattern

## Randomness

- `rand(min, max)`: Random float in range
- `rrand(min, max)`: Random integer in range (inclusive)
- `seed(n)`: Set random seed for reproducibility

## Variables

Store and retrieve values across steps:

- `set("name", value)`: Store a value
- `get("name")`: Retrieve a value

## Sound Parameters

### Core

- `sound(name)`: Create sound command
- `freq(hz)`: Frequency
- `note(midi)`: MIDI note number
- `gain(amp)`: Volume (0.0-1.0)
- `pan(pos)`: Stereo position (-1.0 to 1.0)
- `dur(secs)`: Duration
- `gate(secs)`: Gate time

### Envelope

- `attack(secs)`: Attack time
- `decay(secs)`: Decay time
- `sustain(level)`: Sustain level
- `release(secs)`: Release time

### Filter

- `lpf(hz)`: Lowpass frequency
- `lpq(q)`: Lowpass resonance
- `hpf(hz)`: Highpass frequency
- `bpf(hz)`: Bandpass frequency

### Effects

- `delay(mix)`: Delay amount
- `delaytime(secs)`: Delay time
- `delayfeedback(amt)`: Delay feedback
- `verb(mix)`: Reverb amount
- `verbdecay(secs)`: Reverb decay

### Modulation

- `vib(hz)`: Vibrato rate
- `vibmod(amt)`: Vibrato depth
- `fm(hz)`: FM modulator frequency
- `fmh(ratio)`: FM harmonic ratio

### Sample Playback

- `speed(ratio)`: Playback speed
- `begin(pos)`: Start position (0.0-1.0)
- `end(pos)`: End position (0.0-1.0)

## Examples

Conditional based on step:

```
if step % 4 == 0 {
    sound("kick").gain(1.0)
} else {
    sound("hat").gain(0.5)
}
```

Random variation:

```
sound("synth")
    .freq(rand(200.0, 800.0))
    .gain(rand(0.3, 0.7))
```

Using variables:

```
let n = get("counter");
set("counter", n + 1);
sound("beep").note(60 + (n % 12))
```