This change adds another layer of complexity and control to
the particle system. There are now two code chunks: the old
code that's run per-particle, and new code that's run for
the effect itself. This allows for effect lifetime to be set
by the script (eg, randomly), as well as the emission rate.
Rate can vary over time (see pulse.json), and particles can
be emitted in bursts by setting the effect's burst field
(see fireworks.json).
Additionally, the effect has its own frame of reference and
color, which becomes the default state for newly emitted
particles. This allows synchronizing state across particles
in various interesting ways (see color in fireworks.json).
Change-Id: Iec2f7a3427ce1d6411ed7ef5b3023cbef2e8a134
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/240498
Reviewed-by: Brian Osman <brianosman@google.com>
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
d46cb9729b