[game] Save and restore actors

game/actor.ts

@@ -3,6 +3,15 @@ import { btn, Button } from "./input";
 import { Vec2, new_v2, vadd, vnorm, vmul } from "./vector";
 import { spr, use_texture, Texture } from "./graphics";
 
+interface ActorSnapshot {
+  __type__: string;
+  velocity: Vec2;
+  friction: number;
+  id: string;
+  position: Vec2;
+  bounds: Vec2;
+}
+
 export class Actor {
   velocity: Vec2 = new_v2(0);
   friction: number = 0.6;
@@ -40,6 +49,19 @@ export class Actor {
   draw(_clock: number) {}
 
   bonk(_other: Actor) {}
+
+  snapshot(): ActorSnapshot {
+    return { ...this, __type__: "??" };
+  }
+
+  assign_snapshot(s: ActorSnapshot) {
+    this.id = s.id;
+    this.position = s.position;
+    this.bounds = s.bounds;
+    this.velocity = s.velocity;
+    this.friction = s.friction;
+    return this;
+  }
 }
 
 const robo_info = {
@@ -52,6 +74,10 @@ const robo_info = {
   ],
 };
 
+interface RoboSnapshot extends ActorSnapshot {
+  __type__: "robo";
+}
+
 export class Robo extends Actor {
   bot_sprite: Texture | undefined = undefined;
 
@@ -96,4 +122,25 @@ export class Robo extends Actor {
       spr(x, y, w, h, frame * w, 0, 32, 32);
     }
   }
+
+  snapshot(): RoboSnapshot {
+    return { ...super.snapshot(), __type__: "robo" };
+  }
+
+  assign_snapshot(s: RoboSnapshot) {
+    super.assign_snapshot(s);
+    return this;
+  }
+}
+
+const SNAPSHOT_TABLE: { [key: string]: (s: any) => Actor } = {
+  robo: (s: any) => new Robo(new_v2(0)).assign_snapshot(s),
+};
+
+export function actor_from_snapshot(s: ActorSnapshot): Actor {
+  const f = SNAPSHOT_TABLE[s.__type__];
+  if (f == undefined) {
+    throw new Error("No handler for " + s.__type__);
+  }
+  return f(s);
 }

game/main.ts

@@ -2,7 +2,7 @@ import { cls, print } from "./graphics";
 import { since_start } from "./time";
 import { new_v2 } from "./vector";
 import { load_world, World, Level, draw_level } from "./level";
-import { Actor, Robo } from "./actor";
+import { Actor, Robo, ActorSnapshot, actor_from_snapshot } from "./actor";
 
 /// A nice looping frame counter.
 let clock = 0;
@@ -34,7 +34,7 @@ function load_assets() {
   });
 }
 
-const actors: Actor[] = [];
+let actors: Actor[] = [];
 
 // TODO: Build a system whereby the signatures of the fundamental functions can be checked.
 
@@ -44,11 +44,24 @@ export function init() {
   actors.push(new Robo(new_v2(10, 10)));
 }
 
-export function suspend() {
-  return { clock };
+interface Snapshot {
+  clock: number;
+  actors: ActorSnapshot[];
 }
 
-export function resume() {}
+export function suspend(): Snapshot {
+  return {
+    clock,
+    actors: actors.map((a) => a.snapshot()),
+  };
+}
+
+export function resume(snapshot: Snapshot | undefined) {
+  if (snapshot) {
+    clock = snapshot.clock || 0;
+    actors = snapshot.actors.map((a) => actor_from_snapshot(a));
+  }
+}
 
 export function update() {
   clock = (clock + 1) % 20160;