Dispersive caustics — drag the glass through the beam and watch the spectrum move.
Drag a piece of glass to pick it up; let go to drop it, and it tips over and rolls. Hold shift to lift it higher. Lights slide along the floor. Click to select, right-click to switch between move, rotate and scale. Orbit with empty space.
Click a piece of glass or a light to show its own settings at the top of the panel. Delete removes the selected piece.
Ctrl+Z undoes, Ctrl+Y or Ctrl+Shift+Z redoes. Your scene and settings are remembered between visits; Reset puts everything back as it started.
Add elements from the shelf to build a beam path. Photons trace through every one in sequence, refracting at each interface.
Set per piece. 1 is physically correct crown glass, which barely separates. 8–20 is the useful range. IOR stays independent of it.
Sets incidence at the entry face. Past about 132° the violet end exceeds the critical angle and internally reflects away.