Diffusion Limited Aggregation

This is actually a dual random walker and diffusion limited aggregation hybrid:

If a particle is spawned outside the world, it keeps moving until it touches the world, aggregating onto and expanding it.
If a particle is spawned inside the world, it keeps moving until it exits the world, at which point it expand the world by one cell and dies.
Particles may be spawned at seed points, or at random locations chosen in the void or within the world.
Particles have a heading, and randomly turn within a fixed range each turn before advancing forward.
Movement and aggregation happens along cardinal directions (up/down and left/right), and may optionally be allowed along ordinal directions (diagonally).

Settings

Turns upto: Left: Math.PI *; Right: Math.PI *
Bounds: defaults to viewport size
Seeds:
Spawn Particles: Where:; World-vs-Void Balance:
when using "Random Point" strategy above, what's the target proportion for particles spawned within the world
Particles Move: pre-player: 1 step every ms; post-player: 1 step every ms; Allow ordinal (diagonal) moves; Terminate after steps
if set to 0 then max(bounds.w, bounds.h)/2 is used.
Particle Limit: Stop spawning after
if set to 0 then (bounds.w * bounds.h)/3 is used.

<Space> hold to display hidden cell information

Inspired by 2015-10 codepen by DonKarlssonSan

Other resources: