an example on how to draw confetti in pico-8

confetti.p8

function create_confetti()
  v=1.4  --initial velocity
  size=40
   -- the center of the confetti
  balloon_x=40
  balloon_y=40
  for i=1,100 do
    local r=rnd(size)  -- this is how far out from the center it starts
    local n=rnd(1)     -- this is the angle it goes at
    confetti[i] = {
       dx=v*r*cos(n),     -- dx is delta-X, the rate of change in the x-direction
       dy=20+v*r*sin(n),  -- add 20 for a little boost, it looks better when they start going upward some
       x=balloon_x+cos(n)*r,
       y=balloon_y+sin(n)*r,
       clr=3+rnd(12),    -- random color
      }
  end
end

function update_confetti(dt)
 local friction=.6
 local gravity=.4
 for c in all(confetti) do
  -- calculate new position
  c["x"] += c["dx"] * dt
  c["y"] += c["dy"] * dt
  
  -- slow down the confetti a bit
  c["dx"] -= c["dx"] * friction * dt
  c["dy"] -= c["dy"] * friction * dt
 
  -- gravity pulls it down
  c["dy"] += gravity
 end
end

function draw_confetti()
 for c in all(confetti) do
  rect(c["x"], c["y"], c["x"], c["y"], c["clr"])
 end
end