[question] how to set particle's alpha as 0 when it is born?

[jcyuan]

I'd like to have an effect: generate particle with alpha = 0, then fade in, then fade out...

[DblK]

A lot late, but I found the solution elsewhere. Here is the code:

emitter.setAlpha(function (p, k, t) {
  return 1 - 2 * Math.abs(t - 0.5);
});