defer calculation of more scene properties

src/mol-gl/scene.ts

 /**
- * Copyright (c) 2018-2022 mol* contributors, licensed under MIT, See LICENSE file for more info.
+ * Copyright (c) 2018-2023 mol* contributors, licensed under MIT, See LICENSE file for more info.
  *
  * @author Alexander Rose <alexander.rose@weirdbyte.de>
  * @author David Sehnal <david.sehnal@gmail.com>
@@ -105,6 +105,10 @@ namespace Scene {
         let boundingSphereDirty = true;
         let boundingSphereVisibleDirty = true;
 
+        let markerAverageDirty = true;
+        let opacityAverageDirty = true;
+        let hasOpaqueDirty = true;
+
         let markerAverage = 0;
         let opacityAverage = 0;
         let hasOpaque = false;
@@ -165,9 +169,9 @@ namespace Scene {
             }
 
             renderables.sort(renderableSort);
-            markerAverage = calculateMarkerAverage();
-            opacityAverage = calculateOpacityAverage();
-            hasOpaque = calculateHasOpaque();
+            markerAverageDirty = true;
+            opacityAverageDirty = true;
+            hasOpaqueDirty = true;
             return true;
         }
 
@@ -189,9 +193,9 @@ namespace Scene {
             const newVisibleHash = computeVisibleHash();
             if (newVisibleHash !== visibleHash) {
                 boundingSphereVisibleDirty = true;
-                markerAverage = calculateMarkerAverage();
-                opacityAverage = calculateOpacityAverage();
-                hasOpaque = calculateHasOpaque();
+                markerAverageDirty = true;
+                opacityAverageDirty = true;
+                hasOpaqueDirty = true;
                 visibleHash = newVisibleHash;
                 return true;
             } else {
@@ -268,9 +272,9 @@ namespace Scene {
                 } else {
                     syncVisibility();
                 }
-                markerAverage = calculateMarkerAverage();
-                opacityAverage = calculateOpacityAverage();
-                hasOpaque = calculateHasOpaque();
+                markerAverageDirty = true;
+                opacityAverageDirty = true;
+                hasOpaqueDirty = true;
             },
             add: (o: GraphicsRenderObject) => commitQueue.add(o),
             remove: (o: GraphicsRenderObject) => commitQueue.remove(o),
@@ -311,12 +315,24 @@ namespace Scene {
                 return boundingSphereVisible;
             },
             get markerAverage() {
+                if (markerAverageDirty) {
+                    markerAverage = calculateMarkerAverage();
+                    markerAverageDirty = true;
+                }
                 return markerAverage;
             },
             get opacityAverage() {
+                if (opacityAverageDirty) {
+                    opacityAverage = calculateOpacityAverage();
+                    opacityAverageDirty = true;
+                }
                 return opacityAverage;
             },
             get hasOpaque() {
+                if (hasOpaqueDirty) {
+                    hasOpaque = calculateHasOpaque();
+                    hasOpaqueDirty = true;
+                }
                 return hasOpaque;
             },
         };