add enemy ia

common/utils.ts

@@ -224,6 +224,14 @@ export class Vec2 {
 	public clone() {
 		return new Vec2(this.x(), this.y());
 	}
+
+	public normalize() {
+		return new Vec2(clamp(this.x(), -1, 1), clamp(this.y(), -1, 1));
+	}
+}
+
+export function clamp(x: number, min: number, max: number) {
+	return Math.max(min, Math.min(x, max));
 }
 
 export function v2(x: number, y: number) {

server/entities/enemy.ts

@@ -1,15 +1,37 @@
+import { assert } from "https://deno.land/std@0.221.0/assert/assert.ts";
+import { v2 } from "../../common/utils.ts";
 import { Vec2 } from "../../common/utils.ts";
 import { CompDisplay } from "../components/display.ts";
+import { query_in_rect } from "../components/world.ts";
 import { CompPos } from "../components/world.ts";
+import { CompId, Query } from "../engine.ts";
 import { Engine } from "../engine.ts";
+import { CompPlayer } from "./player.ts";
 
 export class CompEnemy {
 	target;
 	life;
+
 	constructor() {
 		this.target = null as number | null;
 		this.life = 10;
 	}
+
+	get_target_pos(engine: Engine) {
+		if (this.target === null) return null;
+		const result = engine.one(Query.with(CompId).filter(([c]) => c.id === this.target).with(CompPos));
+		if (result === null) return null;
+		const [_, pos] = result;
+		return pos.pos;
+	}
+
+	find_target_from(engine: Engine, pos: Vec2) {
+		const RANGE = v2(2, 2);
+		const found = engine.one(Query.with(CompPlayer).with(CompId).and(query_in_rect(pos.sub(RANGE), pos.add(RANGE))));
+		if (found === null) return this.target = null;
+		const [_, id, __] = found;
+		return this.target = id.id;
+	}
 }
 
 export function sys_spawn_enemy(pos: Vec2) {
@@ -23,3 +45,20 @@ export function sys_spawn_enemy(pos: Vec2) {
 		);
 	};
 }
+
+export function sys_update_enemy() {
+	return (engine: Engine) => {
+		for (const [enemy, enemy_pos] of engine.all(Query.with(CompEnemy).with(CompPos))) {
+			if (enemy.target === null) enemy.find_target_from(engine, enemy_pos.pos);
+			if (enemy.target === null) continue;
+			const pos = enemy.get_target_pos(engine);
+			assert(pos !== null);
+			const direction = pos.sub(enemy_pos.pos);
+			enemy_pos.move_collide(engine, direction.normalize());
+		}
+	};
+}
+
+export function enemy_plugin(engine: Engine) {
+	engine.global_system_loop(sys_update_enemy(), 500);
+}