Driving a shape's radius or count from audio is realizable now; making a shape appear on-the-kick is not

In the current 4-bin Hydra/GLSL rig, audio-reactive shape control is limited to continuous parameter modulation: radius, scale, repeat count can all be driven by a.fft[0] (bass) or other bins in real time. What is not available is onset-triggered shape instantiation — making a new shape appear exactly on the kick drum hit. This requires beat-phase or onset detection, which the rig does not extract. Attempting it by threshold-gating on a.fft[0] will fire too sluggishly and on every loud frame, not on rhythmic transients. Mark onset-triggered shape events as not-yet-possible.

Examples

shape(3, ()=>0.3+a.fft[0]*0.2) scales a triangle with bass — realizable. Spawning a new shape on each kick is not-yet-possible.

Assessment

Explain the difference between continuous audio-reactive shape control and onset-triggered shape events, and state why the latter is not-yet-possible in the current rig.