Added support for terrains in MergeSplitProperties

AGXUnity/MergeSplitProperties.cs

@@ -1,4 +1,5 @@
-using System;
+using AGXUnity.Model;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using UnityEngine;
@@ -145,6 +146,16 @@ protected override bool Initialize()
         }
       }
 
+      var terrains = GetComponentsInChildren<DeformableTerrainBase>();
+      foreach ( var terrain in terrains ) {
+        if ( terrain is DeformableTerrain regular )
+          Add( agxSDK.MergeSplitHandler.getOrCreateProperties( regular.GetInitialized().Native.getGeometry() ) );
+        else if ( terrain is MovableTerrain movable )
+          Add( agxSDK.MergeSplitHandler.getOrCreateProperties( movable.GetInitialized().Native.getGeometry() ) );
+        else if ( terrain is DeformableTerrainPager pager )
+          Debug.LogWarning( $"MergeSplitProperties '{name}' cannot be applied to child '{terrain.name}' as Pagers are not currently supported" );
+      }
+
       GeometryContactThresholds.GetInitialized<GeometryContactMergeSplitThresholds>();
       ConstraintThresholds.GetInitialized<ConstraintMergeSplitThresholds>();