Optional ReadonlyeasingFade Curve.
Applied to the fade progress. "easeInQuad" keeps particles visible longer and drops off at the end.
Optional ReadonlystartFade Start Point.
Fraction of the particle's lifetime after which it starts fading. 0.7 means it is fully visible for the
first 70% of its life and fades to transparent during the last 30%.
Fade-Out Settings.