Feed it sound. Drop a song anywhere, or use Open a song. Microphone hears the room. A browser tab takes the sound of one Chrome tab. Tick “Share tab audio” in the picker.
It hears deep. Two analysers run at once: one long window for the key and a 256-band spectrum, one short window for hits. Each ring of the field is a frequency band, low in the center and high at the edge. The waveform itself traces the mirror edges. Stereo balance tilts the field. A beat tracker makes the whole field swell on the pulse.
Key is color. The field finds the song's key and turns it into a hue on the circle of fifths. C is red. G is orange. D is yellow. A is green. E is cyan. B is blue. F♯ is violet. Some modes bend this toward their own palette.
Modes. Each one is a different visual world: mirror count, palette, trail length, melt, tunnel pull and detail. Afterimage uses a real illusion of the eye, so it works with no music at all. The other six each take the same song somewhere different.
A 3D file. Press Load .OBJ / .STL in the shape row and choose a file. Wavefront .obj and .stl are read, binary or ASCII, and anything else is refused with a note rather than failing quietly. The mesh is drawn off screen every frame, and the field is refracted through its surface: the model's normals push the picture sideways and its depth swells or sinks it, so the kaleidoscope behaves as though it were lit through a glass version of your object. The model turns on its own and the bass drives how hard it bites. Scroll to dolly: the camera physically moves toward the object, so the perspective opens up as you get close, the way a dolly does. It is not a zoom, and the focal length never changes. Load .PDF / .SVG / .PNG takes a logo, renders it, and builds it as a rounded solid the same way. A flattened vector PDF works best. Text builds whatever you type into a rounded solid, in a choice of typefaces, and the round slider sets how soft its edges are. The other objects are built in: the accretion a, a trefoil Knot, an Infinity loop, Concentric rings, a Mobius strip, a a Lotus, a Mandala, a Harmonic standing wave, a Klein bottle, a Supershape and a Torus. Drag to spin the object, and it keeps turning when you let go.
Shape. The row under the modes folds the whole field onto a polygon or a star instead of a circle. It changes the geometry everything else is built on, so a square field and a round one read as different instruments.
Depth sets how long the trails hold. Drift sets how fast the field turns. React sets how hard the music moves the image: rings, edges, kicks, spin. Bass sets how far the low end bends the deep background: the trails and the far layer bend most, the front pattern less. Spiral twists the field into a vortex and draws it down into the center. Higher is faster. Zoom is the endless fall: the pattern is drawn in log-polar space, so the dive into the center never ends and never blurs.
It follows the song. A build, a drop and a breakdown are detected from the energy of the last sixteen seconds. On the drop the mirrors double, the spiral jumps and the color flips to its complement for a bar. Every eighth bar, time slows for two beats. Tonal passages flow, noisy ones fracture. The melody travels down the tunnel as a glowing thread. Old shapes fade into their complementary color, like real afterimages. A living skin, a reaction-diffusion system, breeds under the geometry with the bass and mids. Wide stereo pulls the two halves apart. Kicks split the colors for an instant.
Hands. The picture leans toward the cursor. Click to drop a ripple there. Hold the button to open a gravity well that pulls the field in. Drag sideways to spin, drag up and down to dive or back out. Scroll to dive faster or reverse. Pinch, or hold ctrl while scrolling, to add or remove mirrors. Double-click for fullscreen. The console is never affected.
MIDI. Press MIDI and hit your kit. Kick, snare, hats, toms and cymbals each do their own thing, with no detection guesswork.
Anchor makes everything slow, warm and steady. It shows the clock and a breath to follow. Press it when it becomes too much. Press again to return.
Nothing here strobes. Every change is smoothed. Keys: space play, 1–7 modes, A anchor, F fullscreen, H hide controls. If you are photosensitive, keep depth low and the room lit.