fillReveal static method

double fillReveal(
  1. double sizeT
)

Opacity of the droplet's solid fill, ramping in over the last 30 % of the size curve so the glass droplet has already arrived before it takes on the sheet's opaque surface.

Fading the fill is safe; fading the glass itself is not — a shader backdrop pass renders fully or not at all, so an animated Opacity over it pops. The droplet's glass therefore stays at full strength for the whole morph and only this plain colour layer crossfades.

Implementation

static double fillReveal(double sizeT) =>
    ((sizeT - 0.7) / 0.3).clamp(0.0, 1.0);