From 8cafea1e3f7c426aa161d636ca0590e2b2a4e81d Mon Sep 17 00:00:00 2001
From: Mark <mark@remarkablemark.org>
Date: Mon, 20 Jan 2025 21:19:36 -0500
Subject: [PATCH] chore: make enemy follow player

---
 src/constants/index.ts    |  1 +
 src/constants/tags.ts     |  3 +++
 src/gameobjects/enemy.ts  | 18 +++++++++++++++++-
 src/gameobjects/player.ts | 12 +++++++++++-
 src/scenes/game.ts        |  9 +--------
 5 files changed, 33 insertions(+), 10 deletions(-)
 create mode 100644 src/constants/index.ts
 create mode 100644 src/constants/tags.ts

diff --git a/src/constants/index.ts b/src/constants/index.ts
new file mode 100644
index 0000000..ab25ba9
--- /dev/null
+++ b/src/constants/index.ts
@@ -0,0 +1 @@
+export * from './tags'
diff --git a/src/constants/tags.ts b/src/constants/tags.ts
new file mode 100644
index 0000000..4bc7beb
--- /dev/null
+++ b/src/constants/tags.ts
@@ -0,0 +1,3 @@
+export enum Tag {
+  'player' = 'player',
+}
diff --git a/src/gameobjects/enemy.ts b/src/gameobjects/enemy.ts
index 6d0fe84..7feef66 100644
--- a/src/gameobjects/enemy.ts
+++ b/src/gameobjects/enemy.ts
@@ -1,5 +1,21 @@
+import { Tag } from '../constants'
 import { ghosty } from '../sprites'
 
+const ENEMY_SPEED = 200
+
 export function addEnemy(x: number, y: number) {
-  return add([ghosty, pos(x, y), anchor('center')])
+  const enemy = add([ghosty, pos(x, y), anchor('center')])
+
+  enemy.onUpdate(() => {
+    const player = get(Tag.player)[0]
+
+    if (!player) {
+      return
+    }
+
+    const dir = player.pos.sub(enemy.pos).unit()
+    enemy.move(dir.scale(ENEMY_SPEED))
+  })
+
+  return enemy
 }
diff --git a/src/gameobjects/player.ts b/src/gameobjects/player.ts
index 960b611..431711d 100644
--- a/src/gameobjects/player.ts
+++ b/src/gameobjects/player.ts
@@ -1,5 +1,15 @@
+import { Tag } from '../constants'
+import { addCursorKeys } from '../events'
 import { bean } from '../sprites'
 
 export function addPlayer(x = center().x, y = center().y) {
-  return add([bean, pos(x, y), rotate(0), anchor('center')])
+  const player = add([bean, pos(x, y), rotate(0), anchor('center'), Tag.player])
+
+  player.onUpdate(() => {
+    player.angle += 120 * dt()
+  })
+
+  addCursorKeys(player)
+
+  return player
 }
diff --git a/src/scenes/game.ts b/src/scenes/game.ts
index 73208b4..871c679 100644
--- a/src/scenes/game.ts
+++ b/src/scenes/game.ts
@@ -1,15 +1,8 @@
-import { addCursorKeys } from '../events'
 import { addEnemy, addPlayer } from '../gameobjects'
 import { Scene } from '../types'
 
 scene(Scene.game, () => {
-  const player = addPlayer()
-
-  player.onUpdate(() => {
-    player.angle += 120 * dt()
-  })
-
-  addCursorKeys(player)
+  addPlayer()
 
   onClick(() => addKaboom(mousePos()))