particles.p8

-- emitter

-- emitters have a name and
-- contain particles.
-- update and draw by name.

_e={}

-- create emitter ------------

function e_new(target,x,y,lt,loop)
  emitter={
    x=x,
    y=y,
    lifetime=lt,
    p={},
    loop=loop
  }
  add(_e,emitter)
  
  _debug="emitter count:"..#_e
  return emitter
end

-- add particle to emitter ---

function e_add(emitter,count)
  for i=1,count do
   local p = {
     x=emitter.x,
     y=emitter.y,
        t = 0,
        size = 1,
        max_size = 1,
        lifetime=emitter.lifetime+rnd(5),
        dy = rnd(0.6)+.5-rnd(1),
        dx = rnd(0.2)+.5-rnd(1),
        ddy = -0.1,
        col = 1
   }
   add(emitter.p,p)
 end
end

function e_update(emitter)
  for p in all(emitter.p) do
    p.y += p.dy
    p.x += p.dx
    p.dy+= p.ddy
    p.t += .5*1/p.lifetime
    p.size = max(p.size, p.max_size * p.t )
    if (p.t > 0.2) p.col = 12
    if (p.t > 0.4) p.col = 12
    if (p.t > 0.6) p.col = 13
    if (p.t > 0.8) p.col = 5
    if (p.t > 1) then
      del(emitter.p,p)
      if (emitter.loop) then
        e_add(target,1)
      else
        if (#emitter.p==0) del(_e,emitter)
      end
    end
  end
end

function e_draw(emitter)
  for p in all(emitter.p) do
    pset(p.x, p.y, p.col)
  end
end