The p5.Particle is a library which adds particle support to p5.js, created by Robert Cock. The Particle object, which is simply a data definition, and the Fountain object, which encapsulates all the needed properties for creating Particle, can be used to create data-driven effects. In this library, all particles that are defined in the parent Fountain has a common properties, such as gravity. It is easy for user to add per-particle properties, such as color. When a Particle’s “location” is greater than the canvas height, “life” is greater than or equal to one, or “partSize” is less than 0.1 or 3, the Particle will be deallocated.

Library Link: https://github.com/bobcgausa/cook-js#how-does-this-work

Code Example: http://jsfiddle.net/bobcook/rLvhc8h2/

This example shows generating pattern with rate.