Support for OffscreenCanvas in Web Workers playcanvas#2481

package.json

@@ -64,6 +64,7 @@
       "TWEEN": "readonly",
       "twgsl": "readonly",
       "webkitAudioContext": "readonly",
+      "WorkerGlobalScope": "readonly",
       "XRRay": "readonly",
       "XRRigidTransform": "readonly",
       "XRWebGLLayer": "readonly"

src/core/platform.js

@@ -17,8 +17,10 @@ const detectPassiveEvents = () => {
 };
 
 const ua = (typeof navigator !== 'undefined') ? navigator.userAgent : '';
-const environment = typeof window !== 'undefined' ? 'browser' :
-    typeof global !== 'undefined' ? 'node' : 'worker';
+const environment =
+        typeof window !== 'undefined' ? 'browser' :
+        typeof WorkerGlobalScope !== 'undefined' ? 'webworker' :
+        typeof global !== 'undefined' ? 'node' : 'worker';
 
 // detect platform
 const platformName =
@@ -78,7 +80,8 @@ const platform = {
     global: (typeof globalThis !== 'undefined' && globalThis) ??
         (environment === 'browser' && window) ??
         (environment === 'node' && global) ??
-        (environment === 'worker' && self),
+        (environment === 'worker' && self) ??
+        (environment === 'webworker' && WorkerGlobalScope),
 
     /**
      * Convenience boolean indicating whether we're running in the browser.
@@ -87,6 +90,13 @@ const platform = {
      */
     browser: environment === 'browser',
 
+    /**
+     * True if running in a Web Worker.
+     *
+     * @type {boolean}
+     */
+    webworker: environment === 'webworker',
+
     /**
      * True if running on a desktop or laptop device.
      *

src/framework/app-base.js

@@ -2023,7 +2023,7 @@ const makeTick = function (_app) {
         if (application.xr?.session) {
             application.frameRequestId = application.xr.session.requestAnimationFrame(application.tick);
         } else {
-            application.frameRequestId = platform.browser ? window.requestAnimationFrame(application.tick) : null;
+            application.frameRequestId = platform.browser || platform.webworker ? requestAnimationFrame(application.tick) : null;
         }
 
         if (application.graphicsDevice.contextLost)

src/framework/application.js

@@ -115,7 +115,7 @@ class Application extends AppBase {
      * - sound ({@link SoundComponentSystem})
      * - sprite ({@link SpriteComponentSystem})
      *
-     * @param {HTMLCanvasElement} canvas - The canvas element.
+     * @param {HTMLCanvasElement | OffscreenCanvas} canvas - The canvas element.
      * @param {object} [options] - The options object to configure the Application.
      * @param {ElementInput} [options.elementInput] - Input handler for {@link ElementComponent}s.
      * @param {Keyboard} [options.keyboard] - Keyboard handler for input.

src/platform/graphics/graphics-device.js

@@ -356,6 +356,16 @@ class GraphicsDevice extends EventHandler {
         flags: CLEARFLAG_COLOR | CLEARFLAG_DEPTH
     };
 
+    /**
+     * The current client rect.
+     *
+     * @type {{ width: number, height: number }}
+     */
+    clientRect = {
+        width: 0,
+        height: 0
+    };
+
     static EVENT_RESIZE = 'resizecanvas';
 
     constructor(canvas, options) {
@@ -752,7 +762,16 @@ class GraphicsDevice extends EventHandler {
     }
 
     updateClientRect() {
-        this.clientRect = this.canvas.getBoundingClientRect();
+        if (platform.browser) {
+            const rect = this.canvas.getBoundingClientRect();
+            this.clientRect.width = rect.width;
+            this.clientRect.height = rect.height;
+
+        } else if (platform.webworker) {
+            // Web Workers don't do page layout, so getBoundingClientRect is not available
+            this.clientRect.width = this.canvas.width;
+            this.clientRect.height = this.canvas.height;
+        }
     }
 
     /**