Features to add:

gravity

hint: update velocity by force $($gravity$)$ in $-y$ direction

ground collision

hint: keep particles from going below ground plane

directional velocity

hint: provide minVel and maxVel arguments to initParticles

wind

hint: add a force with a vector direction

elasticity

hint: make particles bounce off ground plane by reversing vel y value

friction

hint: slow down particles in $x$ and $z$ each frame they collide with the ground

# HW$2$ Extra credit

emitter

create new particles each frame

lifetime

give the particles a lifetime in frames and delete$/$hide them once they "die"

color as a function of age

assign a material with a color to each particle and animate the color as a

function of the particle's age

X$.$ any other cool feature you can think of