effectivePress function
The press depth a painter should draw: p itself (springs may
overshoot outside 0, 1), or under Reduce Motion the discrete pressed
artwork (motion brief §2.2.5) — 1 for any press, 0 at rest.
Implementation
double effectivePress(double p, {required bool reduceMotion}) {
if (!reduceMotion) return p;
return p > 0.01 ? 1 : 0;
}