Safer implementation, handle edge cases as done previously

Author: Beilinson

packages/engine/Source/DataSources/BillboardVisualizer.js

@@ -41,6 +41,7 @@ function EntityData(entity) {
   this.entity = entity;
   this.billboard = undefined;
   this.textureValue = undefined;
+  this.subRegion = undefined;
 }
 
 /**
@@ -128,10 +129,12 @@ BillboardVisualizer.prototype.update = function (time) {
       billboard.id = entity;
       item.billboard = billboard;
       item.textureValue = undefined;
+      item.subRegion = undefined;
     }
 
     billboard.show = show;
-    if (item.textureValue !== textureValue) {
+    const imageUpdated = item.textureValue !== textureValue;
+    if (imageUpdated) {
       billboard.image = textureValue;
       item.textureValue = textureValue;
     }
@@ -232,13 +235,16 @@ BillboardVisualizer.prototype.update = function (time) {
       time,
       boundingRectangleScratch,
     );
-    if (
-      defined(subRegion) &&
-      !BoundingRectangle.equals(subRegion, item.subRegion)
-    ) {
-      billboard.setImageSubRegion(billboard.image, subRegion);
+    const subRegionUpdated = !BoundingRectangle.equals(
+      subRegion,
+      item.subRegion,
+    );
+    if (subRegionUpdated) {
       item.subRegion = BoundingRectangle.clone(subRegion, item.subRegion);
     }
+    if (defined(subRegion) && (imageUpdated || subRegionUpdated)) {
+      billboard.setImageSubRegion(billboard.image, subRegion);
+    }
   }
   return true;
 };

packages/engine/Source/Scene/BillboardTexture.js

@@ -268,6 +268,11 @@ BillboardTexture.prototype.addImageSubRegion = async function (id, subRegion) {
     return;
   }
 
+  if (this._id !== id) {
+    // Another load was initiated and resolved resolved before this one. This operation is cancelled.
+    return;
+  }
+
   if (!defined(index) || index === -1) {
     this._loadState = BillboardLoadState.FAILED;
     this._index = -1;