feat(Core/Movement): port smooth waypoint movement from Cataclysm Preservation Project (#25106)

Co-authored-by: blinkysc <blinkysc@users.noreply.github.com>
Co-authored-by: Ovahlord <dreadkiller@gmx.de>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: Kitzunu <Kitzunu@users.noreply.github.com>

src/server/game/Movement/Spline/MoveSpline.h

@@ -122,6 +122,7 @@ namespace Movement
         [[nodiscard]] Vector3 FinalDestination() const { return Initialized() ? spline.getPoint(spline.last()) : Vector3(); }
         [[nodiscard]] Vector3 CurrentDestination() const { return Initialized() ? spline.getPoint(point_Idx + 1) : Vector3(); }
         [[nodiscard]] int32 currentPathIdx() const;
+        [[nodiscard]] int32 MaxPathIdx() const { return spline.last() - 1; }
 
         [[nodiscard]] bool HasAnimation() const { return splineflags.animation; }
         [[nodiscard]] uint8 GetAnimationType() const { return splineflags.animId; }

src/server/game/Movement/Spline/MoveSplineInit.cpp

@@ -199,6 +199,25 @@ namespace Movement
         args.flags.EnableFacingAngle();
     }
 
+    void MoveSplineInit::MoveTo(Vector3 const& start, Vector3 const& dest, bool generatePath, bool forceDestination)
+    {
+        if (generatePath)
+        {
+            PathGenerator path(unit);
+            bool result = path.CalculatePath(start.x, start.y, start.z, dest.x, dest.y, dest.z, forceDestination);
+            if (result && !(path.GetPathType() & PATHFIND_NOPATH))
+            {
+                MovebyPath(path.GetPath());
+                return;
+            }
+        }
+
+        args.path_Idx_offset = 0;
+        args.path.resize(2);
+        TransportPathTransform transform(unit, args.TransformForTransport);
+        args.path[1] = transform(dest);
+    }
+
     void MoveSplineInit::MoveTo(const Vector3& dest, bool generatePath, bool forceDestination)
     {
         if (generatePath)

src/server/game/Movement/Spline/MoveSplineInit.h

@@ -99,6 +99,7 @@ namespace Movement
 
         /* Initializes simple A to B motion, A is current unit's position, B is destination
          */
+        void MoveTo(Vector3 const& start, Vector3 const& destination, bool generatePath = true, bool forceDestination = false);
         void MoveTo(const Vector3& destination, bool generatePath = false, bool forceDestination = false);
         void MoveTo(float x, float y, float z, bool generatePath = false, bool forceDestination = false);