Remove redundant elevation source from TableTop micro app (#809)

* remove redundant elevation source from TableTop micro app

* update code snippet of TableTop readme

* update readme code snippet to match micro app

* set opacity on existing base surface instead of creating a new one

* remove redundant import

Author: gunt0001

microapps/ArTabletopApp/app/src/main/java/com/arcgismaps/toolkit/artabletopapp/screens/MainScreen.kt

@@ -41,8 +41,6 @@ import com.arcgismaps.LoadStatus
 import com.arcgismaps.data.ArcGISFeature
 import com.arcgismaps.geometry.Point
 import com.arcgismaps.mapping.ArcGISScene
-import com.arcgismaps.mapping.ElevationSource
-import com.arcgismaps.mapping.Surface
 import com.arcgismaps.mapping.layers.ArcGISSceneLayer
 import com.arcgismaps.mapping.view.ScreenCoordinate
 import com.arcgismaps.toolkit.ar.TableTopSceneView
@@ -60,12 +58,8 @@ fun MainScreen() {
     val arcGISScene = remember {
         ArcGISScene().apply {
             operationalLayers.add(arcGISSceneLayer)
-            baseSurface = Surface().apply {
-                elevationSources.add(
-                    ElevationSource.fromTerrain3dService()
-                )
-                opacity = 0f
-            }
+            // for the purpose of this sample, we want the base surface to be fully transparent
+            baseSurface.opacity = 0f
         }
     }
     val arcGISSceneAnchor = remember {

toolkit/ar/README.md

@@ -57,7 +57,7 @@ If ARCore is not optional for your application to function (as is the case with
 <meta-data android:name="com.google.ar.core" android:value="required" />
 ```
 
-Configure an `ArcGISScene` with the data you want to render in the table top scene:
+Configure an `ArcGISScene` with the data and base surface required for your table top use case:
 
 ```kotlin
 
@@ -69,11 +69,7 @@ fun MainScreen() {
             operationalLayers.add(
                 ArcGISSceneLayer("https://tiles.arcgis.com/tiles/P3ePLMYs2RVChkJx/arcgis/rest/services/DevA_BuildingShells/SceneServer")
             )
-            baseSurface = Surface().apply {
-                elevationSources.add(
-                    ElevationSource.fromTerrain3dService()
-                )
-            }
+            baseSurface.opacity = 0f
         }
     }
     ...