Fix draped imagery removal

CHANGES.md

@@ -12,6 +12,7 @@
 - Improved performance and reduced memory usage of `Event` class. [#12896](https://github.com/CesiumGS/cesium/pull/12896)
 - Fixes vertical misalignment of glyphs in labels with small fonts [#8474](https://github.com/CesiumGS/cesium/issues/8474)
 - Prevent runtime errors for certain forms of invalid PNTS files [#12872](https://github.com/CesiumGS/cesium/issues/12872)
+- Fixed a bug where the removal of draped imagery layers did not update the rendered state [#12923](https://github.com/CesiumGS/cesium/issues/12923)
 
 #### Additions :tada:
 

packages/engine/Source/Scene/Model/ModelImagery.js

@@ -100,6 +100,9 @@ class ModelImagery {
     //>>includeEnd('debug');
 
     if (!this._hasImagery) {
+      // When there is no imagery, make sure to delete any model primitive
+      // imageries that may previously have been created
+      this._deleteModelPrimitiveImageries();
       return;
     }
 
@@ -215,6 +218,7 @@ class ModelImagery {
       modelPrimitiveImagery.destroy();
     }
     delete this._modelPrimitiveImageries;
+    this._model.resetDrawCommands();
   }
 
   /**

packages/engine/Specs/Scene/Model/ModelImagerySpec.js

@@ -133,4 +133,30 @@ describe("Scene/Model/ModelImagery", function () {
     const modelPrimitiveImageries = modelImagery._modelPrimitiveImageries;
     expect(modelPrimitiveImageries.length).toBe(4);
   });
+
+  it("removes ModelPrimitiveImagery objects when imagery layers are removed", async function () {
+    if (!scene.context.webgl2) {
+      return;
+    }
+
+    const tileset = await loadTilesetWithImagery(scene);
+
+    const root = tileset.root;
+    const content = root.content;
+    const model = content._model;
+    const modelImagery = model._modelImagery;
+
+    // The model has four primitives
+    const modelPrimitiveImageries = modelImagery._modelPrimitiveImageries;
+    expect(modelPrimitiveImageries.length).toBe(4);
+
+    // Remove the imagery layer from the tileset, and trigger an update
+    tileset.imageryLayers.removeAll(false);
+    scene.renderForSpecs();
+
+    // The model imagery should no longer contain any
+    // modelPrimitiveImagery objects now
+    const newModelPrimitiveImageries = modelImagery._modelPrimitiveImageries;
+    expect(newModelPrimitiveImageries).toBeUndefined();
+  });
 });