Audio-reactive glass shapes

A rectangular ui.shape can bind its height to the shared audio spectrum:

ui.glass{ w = 400, h = 240,
    ui.shape{ key = "column", w = 20, h = 160, dx = 40, dy = 40,
        align = "topLeading", radius = 9, hit = false,
        spectrum = { band = 0.5, inset = 4, response = 0.276, bounce = 0.43 },
    },
}

band ranges from 0 (low frequencies) to 1 (high frequencies). The existing 60-band analyzer is area-resampled into 24 bands, then interpolated at that position. The height fraction is min(1, level^1.4 * gain) * taper. gain defaults to 1 and accepts 0–10; taper defaults to 1 and accepts 0–1.

The explicit h is the maximum envelope, including inset. The inset defaults to 0 and accepts 0–256 points. Growth preserves the bottom edge of the unrotated rectangle; rotate turns that growth direction with the rectangle. threshold defaults to 0 and accepts 0–256 points; smaller levels are hidden. Width must be positive and height greater than the inset.

Spectrum geometry has one native owner. These rectangles require hit = false and cannot also use animate, morph, reveal or follow. Their spring defaults to response 0.276 and bounce 0.43, with the usual 0.05–2.5 response and 0–0.95 bounce ranges. Reduce Motion disables interpolation while levels continue to update.

Only mounted bindings request system audio. Removing them removes that demand; the native driver stops when its surface is hidden. Enabling audio for the first time can show macOS’s system-audio recording permission prompt. Vitreus leaves the visualiser off by default. Do not read ctx.data.spectrum just to drive these shapes: the engine uses the shared 30 Hz bands without per-update Luau rendering.