implement belt system

src/lib/sim/BeltSystem.h

@@ -0,0 +1,117 @@
+#pragma once
+
+#include <functional>
+#include <map>
+#include <optional>
+#include <utility>
+#include <vector>
+
+#include <QPoint>
+#include <QPointF>
+#include <QRect>
+
+#include "Item.h"
+#include "ItemType.h"
+#include "Port.h"
+#include "Rotation.h"
+
+// Carries item type and fractional world position for the renderer.
+// worldPos is in tile units (1 tile = 1.0 unit); origin matches tile coords.
+struct VisualItem
+{
+    ItemType type;
+    QPointF worldPos;
+};
+
+// Isolated belt-and-splitter transport layer.  See architecture.md §Belt Subsystem.
+//
+// Buildings interact only through tryPutItem / tryTakeItem.
+// Rendering reads only through forEachVisualItem.
+// No other system inspects tile contents.
+class BeltSystem
+{
+public:
+    explicit BeltSystem(double beltSpeedTilesPerSecond);
+
+    // -- Placement -----------------------------------------------------------
+    // Register a new belt tile.  Any items already on this tile are cleared.
+    void placeBelt(QPoint tile, Rotation direction);
+
+    // Register a new splitter tile.  outputA and outputB are the two exit
+    // directions (e.g. West and East for a default-rotation splitter).
+    // Items entering from any adjacent belt whose direction points into this
+    // tile are held and routed to one of the two outputs.
+    void placeSplitter(QPoint tile, Rotation outputA, Rotation outputB);
+
+    // Remove a belt or splitter tile (on demolish).  Items are discarded.
+    void removeTile(QPoint tile);
+
+    // -- Splitter filter configuration (REQ-BLD-SPLITTER) -------------------
+    // filterA / filterB: empty means "accept all".
+    void setSplitterFilters(QPoint tile,
+                            const std::vector<ItemType>& filterA,
+                            const std::vector<ItemType>& filterB);
+
+    // -- Port interface (buildings <-> belts) --------------------------------
+    // port.tile      = the belt tile adjacent to the building
+    // port.direction = direction items flow on that tile
+    //
+    // tryPutItem: place item onto port.tile entering from the opposite side.
+    //   Returns false if the tile is not a belt, direction mismatches, or tile full.
+    bool tryPutItem(Port port, Item item);
+
+    // tryTakeItem: remove and return the leading item from port.tile.
+    //   Returns nullopt if tile is not a belt, direction mismatches, or tile empty.
+    std::optional<Item> tryTakeItem(Port port);
+
+    // -- Maintenance ---------------------------------------------------------
+    void clearTiles(const std::vector<QPoint>& tiles);   // REQ-UI-BELT-CLEAR
+    void tick();
+
+    // -- Rendering -----------------------------------------------------------
+    void forEachVisualItem(QRect viewportTiles,
+                           std::function<void(VisualItem)> visit) const;
+
+private:
+    void advanceProgress();
+    void moveItemsToNextTile();
+    void routeSplitterItems();
+
+    // Place item into back slot of an existing belt tile at progress 0.
+    // Returns false if tile is not a belt or is full.
+    bool tryPlaceOnBelt(QPoint tile, Item item);
+
+    static std::pair<int, int> key(QPoint tile);
+    static QPoint adjacentTile(QPoint tile, Rotation dir);
+
+    // 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;
+        std::optional<BeltItemSlot> front;  // higher progress; closer to output
+        std::optional<BeltItemSlot> back;   // lower progress; closer to input
+    };
+
+    struct SplitterTile
+    {
+        Rotation outputA;
+        Rotation outputB;
+        std::vector<ItemType> filterA;  // empty = accept all
+        std::vector<ItemType> filterB;
+        bool nextOutputIsA;             // alternation state
+        std::optional<Item> heldItem;   // item buffered waiting to exit
+    };
+
+    double m_progressPerTick;  // beltSpeedTilesPerSecond / kTickRateHz
+
+    std::map<std::pair<int, int>, BeltTile>     m_belts;
+    std::map<std::pair<int, int>, SplitterTile> m_splitters;
+};