Added IActiveMeshCandidateProvider which provides the author a way to reduce active mesh selection work. Can greatly improves FPS on scenes with lots of meshes since the author can know the details of how their scene is setup and can bypass lots of work in determining active meshes by providing a shorter list of candidates.

src/babylon.scene.ts

@@ -3,6 +3,11 @@
         dispose(): void;
     }
 
+    export interface IActiveMeshCandidateProvider {
+        getMeshes(scene: Scene): AbstractMesh[];
+        readonly checksIsEnabled: boolean; // Indicates if the meshes have been checked to make sure they are isEnabled().
+    }
+
     class ClickInfo {
         private _singleClick = false;
         private _doubleClick = false;
@@ -2950,6 +2955,14 @@
             return this._intermediateRendering
         }
 
+        private _activeMeshCandidateProvider: IActiveMeshCandidateProvider;
+        public setActiveMeshCandidateProvider(provider: IActiveMeshCandidateProvider): void {
+            this._activeMeshCandidateProvider = provider;
+        }
+        public getActiveMeshCandidateProvider(): IActiveMeshCandidateProvider {
+            return this._activeMeshCandidateProvider;
+        }
+
         private _activeMeshesFrozen = false;
 
         /**
@@ -2994,26 +3007,40 @@
             // Meshes
             var meshes: AbstractMesh[];
             var len: number;
-
-            if (this._selectionOctree) { // Octree
+            var checkIsEnabled = true;
+
+            // Determine mesh candidates
+            if (this._activeMeshCandidateProvider !== undefined) {
+                // Use _activeMeshCandidateProvider
+                meshes = this._activeMeshCandidateProvider.getMeshes(this);
+                checkIsEnabled = this._activeMeshCandidateProvider.checksIsEnabled === false;
+                if (meshes !== undefined) {
+                    len = meshes.length;
+                } else {
+                    len = 0;
+                }
+            } else if (this._selectionOctree !== undefined) {
+                // Octree
                 var selection = this._selectionOctree.select(this._frustumPlanes);
                 meshes = selection.data;
                 len = selection.length;
-            } else { // Full scene traversal
+            } else {
+                // Full scene traversal
                 len = this.meshes.length;
                 meshes = this.meshes;
             }
 
-            for (var meshIndex = 0; meshIndex < len; meshIndex++) {
-                var mesh = meshes[meshIndex];
+            // Check each mesh
+            for (var meshIndex = 0, mesh, meshLOD; meshIndex < len; meshIndex++) {
+                mesh = meshes[meshIndex];
 
-                if (mesh.isBlocked) {
+                if (mesh.isBlocked === true) {
                     continue;
                 }
 
                 this._totalVertices.addCount(mesh.getTotalVertices(), false);
 
-                if (!mesh.isReady() || !mesh.isEnabled()) {
+                if (mesh.isReady() === false || (checkIsEnabled === true && mesh.isEnabled() === false)) {
                     continue;
                 }
 
@@ -3025,9 +3052,9 @@
                 }
 
                 // Switch to current LOD
-                var meshLOD = mesh.getLOD(this.activeCamera);
+                meshLOD = mesh.getLOD(this.activeCamera);
 
-                if (!meshLOD) {
+                if (meshLOD === undefined || meshLOD === null) {
                     continue;
                 }