A projectM/Milkdrop-style music visualizer for live coding sessions. Odin + Raylib, GLSL feedback shaders, FFT of the desktop audio, and an OSC listener so the live-coding environment (ChucK) can send semantic events the FFT can't hear — note-ons, kicks, scene channels.

./run.sh          # build + run (run from the project root: shaders load from ./shaders)
./build.sh        # build only -> bin/viz

Needs Odin (vendor raylib + miniaudio) and PipeWire/PulseAudio. Audio is captured from the first capture device whose name contains monitor (the desktop's output loopback). Override with a substring match:

VIZ_AUDIO_DEVICE="alsa_output.pci" ./run.sh

int args are accepted anywhere a float is expected; bundles are unpacked. From ChucK:

OscOut osc;
osc.dest("127.0.0.1", 9000);
osc.start("/kick"); 1.0 => osc.add; osc.send();

examples/osc_demo.ck is a full beat + OSC demo to run alongside the app.

Both shaders hot-reload on save while the app runs:

• shaders/warp.fs — the feedback pass (previous frame → current): rotation, zoom, ripple, trail decay. This is where the "motion feel" lives.
• shaders/comp.fs — the composite pass (feedback → screen): palette, spectrum bars, beat flashes, vignette, tone map.

comp.fs gets audioTex, a 512×2 R32F texture: row v=0.25 is the log-binned spectrum (35Hz–16kHz, 0..1), row v=0.75 is the waveform (0.5 = silence). A broken edit keeps the last working shader running.

src/main.odin   window, ping-pong feedback buffers, shader hot reload, uniforms
src/audio.odin  miniaudio capture of the monitor source -> lock-free ring buffer
src/fft.odin    Hann + radix-2 FFT, log binning, band energies, auto-gain
src/osc.odin    non-blocking UDP OSC 1.0 receiver (messages + bundles)

Per frame: warp.fs re-renders the previous frame (buffer A → B, distorted and decayed), the live waveform is drawn into B as additive geometry, comp.fs composites B to the screen, then A and B swap — the Milkdrop feedback loop.