Added prerenderclear event to canvas and webgl

src/renderer/canvas/CanvasRenderer.js

@@ -354,6 +354,7 @@ var CanvasRenderer = new Class({
      * Called at the start of the render loop.
      *
      * @method Phaser.Renderer.Canvas.CanvasRenderer#preRender
+     * @fires Phaser.Renderer.Events#PRE_RENDER_CLEAR
      * @fires Phaser.Renderer.Events#PRE_RENDER
      * @since 3.0.0
      */
@@ -369,6 +370,8 @@ var CanvasRenderer = new Class({
         ctx.globalCompositeOperation = 'source-over';
         ctx.setTransform(1, 0, 0, 1, 0, 0);
 
+        this.emit(Events.PRE_RENDER_CLEAR);
+
         if (config.clearBeforeRender)
         {
             ctx.clearRect(0, 0, width, height);

src/renderer/events/PRE_RENDER_CLEAR_EVENT.js

@@ -0,0 +1,26 @@
+/**
+ * @author       Richard Davey <rich@phaser.io>
+ * @copyright    2013-2024 Phaser Studio Inc.
+ * @license      {@link https://opensource.org/licenses/MIT|MIT License}
+ */
+
+/**
+ * The Pre-Render Clear Event.
+ *
+ * This event is dispatched by the Phaser Renderer. It happens at the start of the render step, before
+ * the WebGL gl.clear function has been called. This allows you to toggle the `config.clearBeforeRender` property
+ * as required, to have fine-grained control over when the canvas is cleared during rendering.
+ * 
+ * Listen to it from within a Scene using: `this.renderer.events.on('prerenderclear', listener)`.
+ * 
+ * It's very important to understand that this event is called _before_ the scissor and mask stacks are cleared.
+ * This means you should not use this event to modify the scissor or mask. Instead, use the `prerender` event for that.
+ * 
+ * If using the Canvas Renderer, this event is dispatched before the canvas is cleared, but after the context globalAlpha
+ * and transform have been reset.
+ *
+ * @event Phaser.Renderer.Events#PRE_RENDER_CLEAR
+ * @type {string}
+ * @since 3.85.0
+ */
+module.exports = 'prerenderclear';

src/renderer/webgl/WebGLRenderer.js

@@ -2643,6 +2643,7 @@ var WebGLRenderer = new Class({
      * Clears the current vertex buffer and updates pipelines.
      *
      * @method Phaser.Renderer.WebGL.WebGLRenderer#preRender
+     * @fires Phaser.Renderer.Events#PRE_RENDER_CLEAR
      * @fires Phaser.Renderer.Events#PRE_RENDER
      * @since 3.0.0
      */
@@ -2655,6 +2656,8 @@ var WebGLRenderer = new Class({
         //  Make sure we are bound to the main frame buffer
         gl.bindFramebuffer(gl.FRAMEBUFFER, null);
 
+        this.emit(Events.PRE_RENDER_CLEAR);
+
         if (this.config.clearBeforeRender)
         {
             var clearColor = this.config.backgroundColor;