From 8e4cafc3d249d151c6f3850129e2362056f2e0b2 Mon Sep 17 00:00:00 2001
From: Colin Espinas <colin.espinas@yahoo.fr>
Date: Wed, 16 Oct 2024 14:13:08 +0200
Subject: [PATCH] feat: added hooks to engine step loop

---
 .changeset/few-schools-explain.md |  5 +++++
 src/core/Engine.ts                | 26 ++++++++++++++++++++++++++
 src/types/options.d.ts            | 16 ++++++++++++++++
 3 files changed, 47 insertions(+)
 create mode 100644 .changeset/few-schools-explain.md

diff --git a/.changeset/few-schools-explain.md b/.changeset/few-schools-explain.md
new file mode 100644
index 0000000..f8e9105
--- /dev/null
+++ b/.changeset/few-schools-explain.md
@@ -0,0 +1,5 @@
+---
+"@ineka/engine": minor
+---
+
+Added hooks to execute code at engine's key locations
diff --git a/src/core/Engine.ts b/src/core/Engine.ts
index 09864d3..061efdc 100644
--- a/src/core/Engine.ts
+++ b/src/core/Engine.ts
@@ -63,6 +63,10 @@ export class Engine {
       fullscreen: true,
       container: 'body',
       framerate: null,
+      hooks: {
+        beforeStep: async () => { },
+        afterStep: async () => { },
+      },
       ...options,
     }
     this._container = document.querySelector(this._options.container as string) as HTMLElement
@@ -98,6 +102,17 @@ export class Engine {
    * to fix the timestep for fixed update loops (useful for physics and user interactions).
    */
   protected step(now: number): void {
+    // Call beforeStep hook
+    try {
+      if (!this.options.hooks || !this.options.hooks.beforeStep) {
+        throw new EngineError(this, 'ENGINE:FAILURE', 'No beforeStep hook given to engine.')
+      }
+      this.options.hooks.beforeStep()
+    }
+    catch (err) {
+      console.error(err)
+    }
+
     if (!this.rootNode) {
       throw new EngineError(this, 'ENGINE:FAILURE', 'No root node given to engine, cannot run.')
     }
@@ -118,6 +133,17 @@ export class Engine {
       system.step(this.time.delta)
     })
     this.rootNode.step(this.time.delta)
+    // Call afterStep hook
+    try {
+      if (!this.options.hooks || !this.options.hooks.afterStep) {
+        throw new EngineError(this, 'ENGINE:FAILURE', 'No afterStep hook given to engine.')
+      }
+      this.options.hooks.afterStep()
+    }
+    catch (err) {
+      console.error(err)
+    }
+
     // Request next step
     requestAnimationFrame(this.step.bind(this))
   }
diff --git a/src/types/options.d.ts b/src/types/options.d.ts
index f1c841d..0cf0928 100644
--- a/src/types/options.d.ts
+++ b/src/types/options.d.ts
@@ -32,4 +32,20 @@ export interface EngineOptions {
    * @default null
    */
   framerate?: number | null
+
+  /**
+   * Hooks are functions that are called at specific points in the engine's runtime.
+   */
+  hooks?: {
+    /**
+     * Called before the engine's step loop.
+     * @default async () => { }
+     */
+    beforeStep: () => Promise<void>
+    /**
+     * Called after the engine's step loop.
+     * @default async () => { }
+     */
+    afterStep: () => Promise<void>
+  }
 }