Animate items emerging from building output ports

src/lib/sim/BeltSystem.h

@@ -10,6 +10,7 @@
 #include <QPointF>
 #include <QRect>
 
+#include "BeltSlot.h"
 #include "Item.h"
 #include "ItemType.h"
 #include "Port.h"
@@ -88,6 +89,11 @@ public:
     //   Returns nullopt if tile is not a belt, direction mismatches, or tile empty.
     std::optional<ItemType> peekItem(Port port) const;
 
+    // Progress advanced per tick at the configured belt speed (tile fraction per
+    // tick). Shared with building output belts so emerging items travel at exactly
+    // the same speed as real belts (REQ-MAT-OUTPUT-EMERGE).
+    double getProgressPerTick_tpt() const { return m_progressPerTick_tpt; }
+
     // -- Maintenance ---------------------------------------------------------
     void clearTiles(const std::vector<QPoint>& tiles);   // REQ-UI-BELT-CLEAR
     void tick();
@@ -126,15 +132,6 @@ private:
     // refused).  Returns false if no transport tile occupies `tile`.
     bool entersThroughOutputEdge(QPoint tile, Rotation travelDir) const;
 
-    // Returns the world-space centre of a slot given tile origin and progress.
-    static QPointF slotWorldPos(QPoint tile, Rotation dir, double progress);
-
-    struct BeltItemSlot
-    {
-        Item item;
-        double progress;  // [0.0, 1.0]: 0 = just entered, 1 = at output edge
-    };
-
     struct BeltTile
     {
         Rotation direction;