particle.mli

open Actors
open Sprite

(* Template params associated with a particle *)
type part_params = {
  sprite: Sprite.sprite;  (* Backing sprite *)
  rot: float;             (* Rotation *)
  lifetime: int;          (* Life span *)
}

type particle = {
  params: part_params;
  part_type: Actors.part_typ;
  pos:  Actors.xy;
  vel:  Actors.xy;
  acc:  Actors.xy;
  mutable kill: bool;     (* Kill the particle in the next frame *)
  mutable life: int;      (* Remaining lifespan of particle *)
}

(* Makes a new particle of the given particle type with at a position. *)
val make : ?vel:float*float -> ?acc:float*float -> Actors.part_typ 
    -> float*float -> Dom_html.canvasRenderingContext2D Js.t -> particle

(* Make a score particle. The first int indicates the score to spawn *)
val make_score : int -> float*float -> Dom_html.canvasRenderingContext2D Js.t 
          -> particle

(* Process a particle, updating its velocity and position. Also marks it as 
 * killable if it exceeds its lifespan *)
val process : particle -> unit