[Terrain] Optimize bulk queries to the Terrain System to retrieve height, surface weights, and normals (#7357)

Code/Framework/AzFramework/AzFramework/SurfaceData/SurfaceData.cpp

@@ -37,6 +37,7 @@ namespace AzFramework::SurfaceData
     {
         if (AZ::SerializeContext* serializeContext = azrtti_cast<AZ::SerializeContext*>(context))
         {
+            serializeContext->Class<AZStd::fixed_vector<SurfaceTagWeight, Constants::MaxSurfaceWeights>>();
             serializeContext->Class<SurfacePoint>()
                 ->Field("m_position", &SurfacePoint::m_position)
                 ->Field("m_normal", &SurfacePoint::m_normal)
@@ -46,6 +47,7 @@ namespace AzFramework::SurfaceData
 
         if (AZ::BehaviorContext* behaviorContext = azrtti_cast<AZ::BehaviorContext*>(context))
         {
+            behaviorContext->Class<AZStd::fixed_vector<SurfaceTagWeight, Constants::MaxSurfaceWeights>>();
             behaviorContext->Class<SurfacePoint>("AzFramework::SurfaceData::SurfacePoint")
                 ->Attribute(AZ::Script::Attributes::Category, "SurfaceData")
                 ->Constructor()

Code/Framework/AzFramework/AzFramework/SurfaceData/SurfaceData.h

@@ -10,13 +10,19 @@
 #include <AzCore/Math/Crc.h>
 #include <AzCore/Math/Vector2.h>
 #include <AzCore/Math/Vector3.h>
-#include <AzCore/std/containers/vector.h>
+#include <AzCore/std/containers/fixed_vector.h>
 
 namespace AzFramework::SurfaceData
 {
     namespace Constants
     {
         static constexpr const char* s_unassignedTagName = "(unassigned)";
+
+        //! The maximum number of surface weights that we can store.
+        //! For performance reasons, we want to limit this so that we can preallocate the max size in advance.
+        //! The current number is chosen to be higher than expected needs, but small enough to avoid being excessively wasteful.
+        //! (Dynamic structures would end up taking more memory than what we're preallocating)
+        static constexpr size_t MaxSurfaceWeights = 16;
     }
 
     struct SurfaceTagWeight
@@ -70,7 +76,7 @@ namespace AzFramework::SurfaceData
         }
     };
 
-    using SurfaceTagWeightList = AZStd::vector<SurfaceTagWeight>;
+    using SurfaceTagWeightList = AZStd::fixed_vector<SurfaceTagWeight, Constants::MaxSurfaceWeights>;
 
     struct SurfacePoint final
     {