feat： Add render hooks to Painter for external render passes

src/render/painter.ts

@@ -79,6 +79,14 @@
     isRenderingGlobe: boolean;
 };
 
+type RenderHookPhase =
+    | 'beforeOpaque'
+    | 'afterOpaque'
+    | 'beforeTranslucent'
+    | 'afterTranslucent';
+
+type RenderHook = (painter: Painter, renderOptions: RenderOptions) => void;
+
 /**
  * @internal
  * Initialize a new painter object.
@@ -135,6 +143,8 @@
     // every time the camera-matrix changes the terrain-facilitators will be redrawn.
     terrainFacilitator: {dirty: boolean; matrix: mat4; renderTime: number};
 
+    _renderHooks: Map<RenderHookPhase, RenderHook[]> = new Map();
+
     constructor(gl: WebGLRenderingContext | WebGL2RenderingContext, transform: IReadonlyTransform) {
         this.context = new Context(gl);
         this.transform = transform;
@@ -560,6 +570,7 @@
         this._showOverdrawInspector = options.showOverdrawInspector;
         this.depthRangeFor3D = [0, 1 - ((style._order.length + 2) * this.numSublayers * this.depthEpsilon)];
 
+        this._runRenderHooks('beforeOpaque',renderOptions);
         // Opaque pass ===============================================
         // Draw opaque layers top-to-bottom first.
         if (!this.renderToTexture) {
@@ -575,6 +586,9 @@
             }
         }
 
+        this._runRenderHooks('afterOpaque',renderOptions);
+        this._runRenderHooks('beforeTranslucent',renderOptions);
+
         // Translucent pass ===============================================
         // Draw all other layers bottom-to-top.
         this.renderPass = 'translucent';
@@ -605,6 +619,8 @@
             this.renderLayer(this, tileManager, layer, coords, renderOptions);
         }
 
+        this._runRenderHooks('afterTranslucent',renderOptions);
+
         // Render atmosphere, only for Globe projection
         if (renderOptions.isRenderingGlobe) {
             drawAtmosphere(this, this.style.sky, this.style.light);
@@ -843,4 +859,30 @@
         const {drawingBufferWidth, drawingBufferHeight} = this.context.gl;
         return this.width !== drawingBufferWidth || this.height !== drawingBufferHeight;
     }
+
+    /**
+     *
+     * @param phase
+     */
+    _runRenderHooks(phase: RenderHookPhase,renderOptions: RenderOptions) {
+        const hooks = this._renderHooks.get(phase);
+        if (!hooks) return;
+        for (const hook of hooks) {
+            hook(this,renderOptions);
+        }
+    }
+
+    /**
+     *
+     * @param phase
+     * @param hook
+     */
+    addRenderHook(phase: RenderHookPhase, hook: RenderHook) {
+        let list = this._renderHooks.get(phase);
+        if (!list) {
+            list = [];
+            this._renderHooks.set(phase, list);
+        }
+        list.push(hook);
+    }
 }