Core/Movement: Implement MoveSplineFlag::Enter_Cycle (#24049)

by xvwyh

(cherry picked from commit 40542f01e3fec0bff2c6e5eadbe20e58f19b0fd8)

4 files changed, 43 insertions, 5 deletions

diff --git a/src/server/game/Movement/MotionMaster.cpp b/src/server/game/Movement/MotionMaster.cpp
index a1ca939c1b4..28c991a3c8d 100644
--- a/src/server/game/Movement/MotionMaster.cpp
+++ b/src/server/game/Movement/MotionMaster.cpp
@@ -859,6 +859,9 @@ void MotionMaster::MoveCirclePath(float x, float y, float z, float radius, bool
 
     Movement::MoveSplineInit init(_owner);
 
+    // add the owner's current position as starting point as it gets removed after entering the cycle
+    init.Path().push_back(G3D::Vector3(_owner->GetPositionX(), _owner->GetPositionY(), _owner->GetPositionZ()));
+
     for (uint8 i = 0; i < stepCount; angle += step, ++i)
     {
         G3D::Vector3 point;
diff --git a/src/server/game/Movement/Spline/MoveSpline.cpp b/src/server/game/Movement/Spline/MoveSpline.cpp
index d2298b8536c..ccfc40eb67d 100644
--- a/src/server/game/Movement/Spline/MoveSpline.cpp
+++ b/src/server/game/Movement/Spline/MoveSpline.cpp
@@ -150,9 +150,8 @@ void MoveSpline::init_spline(MoveSplineInitArgs const& args)
     if (args.flags.cyclic)
     {
         uint32 cyclic_point = 0;
-        // MoveSplineFlag::Enter_Cycle support dropped
-        //if (splineflags & SPLINEFLAG_ENTER_CYCLE)
-        //cyclic_point = 1;   // shouldn't be modified, came from client
+        if (splineflags.enter_cycle)
+            cyclic_point = 1;   // shouldn't be modified, came from client
         spline.init_cyclic_spline(&args.path[0], args.path.size(), modes[args.flags.isSmooth()], cyclic_point, args.initialOrientation);
     }
     else
@@ -304,6 +303,41 @@ MoveSpline::UpdateResult MoveSpline::_updateState(int32& ms_time_diff)
                 point_Idx = spline.first();
                 time_passed = time_passed % Duration();
                 result = Result_NextCycle;
+
+                // Remove first point from the path after one full cycle.
+                // That point was the position of the unit prior to entering the cycle and it shouldn't be repeated with continuous cycles.
+                if (splineflags.enter_cycle)
+                {
+                    splineflags.enter_cycle = false;
+
+                    MoveSplineInitArgs args{ (size_t)spline.getPointCount() };
+                    args.path.assign(spline.getPoints().begin() + spline.first() + 1, spline.getPoints().begin() + spline.last());
+                    args.facing = facing;
+                    args.flags = splineflags;
+                    args.path_Idx_offset = point_Idx_offset;
+                    // MoveSplineFlag::Parabolic | MoveSplineFlag::Animation not supported currently
+                        //args.parabolic_amplitude = ?;
+                        //args.time_perc = ?;
+                    args.splineId = m_Id;
+                    args.initialOrientation = initialOrientation;
+                    args.velocity = 1.0f; // Calculated below
+                    args.HasVelocity = true;
+                    args.TransformForTransport = onTransport;
+                    if (args.Validate(nullptr))
+                    {
+                        // New cycle should preserve previous cycle's duration for some weird reason, even though
+                        // the path is really different now. Blizzard is weird. Or this was just a simple oversight.
+                        // Since our splines precalculate length with velocity in mind, if we want to find the desired
+                        // velocity, we have to make a fake spline, calculate its duration and then compare it to the
+                        // desired duration, thus finding out how much the velocity has to be increased for them to match.
+                        MoveSpline tempSpline;
+                        tempSpline.Initialize(args);
+                        args.velocity = (float)tempSpline.Duration() / Duration();
+
+                        if (args.Validate(nullptr))
+                            init_spline(args);
+                    }
+                }
             }
             else
             {
diff --git a/src/server/game/Movement/Spline/MoveSpline.h b/src/server/game/Movement/Spline/MoveSpline.h
index 20265e23312..e9083eb6417 100644
--- a/src/server/game/Movement/Spline/MoveSpline.h
+++ b/src/server/game/Movement/Spline/MoveSpline.h
@@ -95,9 +95,9 @@ namespace Movement
         int32 next_timestamp() const { return spline.length(point_Idx + 1); }
         int32 segment_time_elapsed() const { return next_timestamp() - time_passed; }
         int32 timeElapsed() const { return Duration() - time_passed; }
-        int32 timePassed() const { return time_passed; }
 
     public:
+        int32 timePassed() const { return time_passed; }
         int32 Duration() const { return spline.length(); }
         MySpline const& _Spline() const { return spline; }
         int32 _currentSplineIdx() const { return point_Idx; }
diff --git a/src/server/game/Movement/Spline/MoveSplineInit.cpp b/src/server/game/Movement/Spline/MoveSplineInit.cpp
index 2757cc933a8..4f68c03bcd8 100644
--- a/src/server/game/Movement/Spline/MoveSplineInit.cpp
+++ b/src/server/game/Movement/Spline/MoveSplineInit.cpp
@@ -86,7 +86,8 @@ namespace Movement
         // correct first vertex
         args.path[0] = real_position;
         args.initialOrientation = real_position.orientation;
-        move_spline.onTransport = !unit->GetTransGUID().IsEmpty();
+        args.flags.enter_cycle = args.flags.cyclic;
+        move_spline.onTransport = transport;
 
         uint32 moveFlags = unit->m_movementInfo.GetMovementFlags();
         if (!args.flags.backward)