# galdr

A terminal **grid synthesizer**. Signal flows downward through a field of
single-glyph unit generators; every incoming MIDI note voices the whole grid;
the mix is rendered low-latency to PipeWire. It is orca's voice — the same
esoteric, spatial approach to programming, but for making sound instead of
sending events.

```
orca-rs  ──MIDI/OSC/UDP──▶  galdr  ──PipeWire──▶  speakers
   compose the pattern       voice it       (spectrust -p visualizes it)
```

## The grid

Signal flows **down**: each cell takes the sample from the cell above as its
input. Glyphs are **UPPERCASE** operators. A digit `0`–`9` to the left/right is
a constant parameter; a lowercase letter `a`–`z` reads MIDI CC (`a` = CC 0).

| glyph | unit generator | left / right param |
|---|---|---|
| `O` | sine | ratio |
| `A` | saw | ratio |
| `U` | pulse | width |
| `V` | triangle | — |
| `N` | noise | — |
| `L` `H` `B` | low / high / band-pass (SVF) | cutoff / resonance |
| `E` | envelope (gated by the note) | attack / release |
| `S` | soft clip (tanh) | drive |
| `C` | hard clip | threshold |
| `F` | wavefolder | amount |
| `D` | decimate / bitcrush | rate |
| `G` | gain | amount |
| `R` | ring modulator | ratio |
| `M` | mix — adds the cell to its **left** | — |
| `!` | output to master | — |

Each `!` sums into the master, so parallel columns stack timbres or voices.
A note plays every column at once.

Example — a filtered saw with an envelope:

```
A        saw at the note pitch
L        lowpass, cutoff from the digit to its left...
E        ...enveloped by the note gate
!        ...to master
```

Editing the grid recompiles and hot-swaps the running program without dropping
audio. There is no embedded scope — run a spectrum analyzer (e.g. `spectrust`)
on the side if you want one.

## Usage

```
galdr [--latency <frames>] [--poly <n>] [--rate <hz>] [--midi-name <s>]
```

galdr creates a virtual MIDI input port named **galdr**; connect orca or any
sequencer/DAW to it. `--midi-name` connects to an existing port instead.

Keys: cursor keys move; type a glyph to place it; Backspace clears; `?` toggles
help; Esc quits. Resize the grid with `(` / `)` (width) and `_` / `+` (height)
by one ruler division, or Ctrl+arrows by one cell (orca's bindings).

Runtime deps: PipeWire and ALSA (MIDI). Built in Rust; reuses the native
PipeWire path from spectrust.