Play Shadertoy and ISF shaders live, with the music

Dancy Ants imports fragment shaders — ISF, Shadertoy and plain GLSL — and plays them like its own scenes: on the decks, under the effects, with Autopilot, full screen on a projector. Here's what maps to what, how to make a shader hear the music, and what doesn't work yet.

In short: in the app, open the shader importer and paste the code (or load a .fs, .isf, .glsl, .frag or .txt file). The format is detected for you. Your shader then sits beside the 40 built-in scenes, and anything you can do to a scene — decks, crossfader, effects, Autopilot — works on it.

What it accepts, and what maps to what

Format	Recognised by	What you get
ISF	The JSON header (`ISFVSN`, `INPUTS`…)	The first four number or on/off inputs become the four knobs. Name, credit and description are read from the header.
Shadertoy	`void mainImage(...)`	Runs as written. The Motion knob scales `iTime`; Shadertoy declares no other inputs.
Plain GLSL	`void main()`	A last resort for fragment shaders in neither format.

Helper functions that clash with the built-in library (everyone writes their own rot() and hash12()) are renamed automatically, so the shader keeps using its own versions.

Making a shader hear the music

A Shadertoy shader doesn't react to sound by itself: Shadertoy's audio comes in through texture channels, and those aren't available here (see below). But every imported shader can read the same live audio the built-in scenes use:

Uniform	What's in it
`u_audio` (vec4)	bass, mid, high, overall level — 0 to 1, live
`u_hits` (vec4)	bass hit, mid hit, high hit, beat — pulses on each onset
`u_beat` (float)	0 → 1 through the current beat
`u_bar` (float)	0 → 1 through the current bar

A minimal Shadertoy-style example — a ring that grows with the bass and flashes on the beat:

void mainImage(out vec4 fragColor, in vec2 fragCoord) {
  vec2 uv = (fragCoord - 0.5 * iResolution.xy) / iResolution.y;
  float bass = u_audio.x;                 // live, 0 to 1
  float r = length(uv);
  float ring = smoothstep(0.02, 0.0, abs(r - 0.2 - 0.25 * bass));
  float flash = 0.6 + 0.4 * u_hits.w;     // pulses on the beat
  fragColor = vec4(vec3(ring * flash), 1.0);
}

Paste a shader like that into the importer and it moves with the music straight away — this one was checked against the importer and compiles. On top of it, the effects, the crossfader and Autopilot behave exactly as they do with any built-in scene.

What doesn't work (yet)

Texture and audio channels. Texture lookups on iChannel0–3 are replaced with procedural noise. Most shaders use channels as a noise source, so many still look close to the original; ones that need a particular image, video or Shadertoy's audio texture won't. Shaders that read a channel with textureLod or texelFetch won't compile yet.
Multi-pass shaders. Shadertoy Buffer A–D and multi-pass ISF aren't supported.
The mouse. iMouse is fixed at the centre of the frame.
Colour inputs in ISF become fixed colours; use the Colour shift and Palette controls instead.

If a shader can't be converted, the importer tells you why. The substitutions above happen quietly, so check the result full screen before a gig.

Licences: read this before a paid gig

A shader belongs to the person who wrote it and carries their licence. Shadertoy's terms put shaders under CC BY-NC-SA 3.0 unless the author says otherwise — which means non-commercial. Playing one at a party at home is one thing; playing it at a gig you're paid for needs the author's permission.

Check the licence in the shader's comments or on its page.
Credit the author — ISF has a CREDIT field for it.
For paid work, write your own, or ask.

The built-in scenes are ours and are covered by your Dancy Ants licence. Imported shaders aren't — see the terms.

Tips

Watch the cost. A shader that runs at 60fps in a small Shadertoy preview may not at projector resolution. Test it full screen on the machine you'll play on.
Map the knobs. In ISF, put your four most useful controls first; they become the knobs, and the knobs can be mapped to MIDI.
Back it up. Back up everything writes your scenes, saved looks and MIDI map to one file you keep.