////  ShapeManager.h//  libraries/physics/src////  Created by Andrew Meadows 2014.10.29//  Copyright 2014 High Fidelity, Inc.////  Distributed under the Apache License, Version 2.0.//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html// #ifndef hifi_ShapeManager_h#define hifi_ShapeManager_h #include <atomic>#include <chrono>#include <vector> #include <QObject>#include <btBulletDynamicsCommon.h>#include <LinearMath/btHashMap.h> #include <ShapeInfo.h> #include "ShapeFactory.h"#include "HashKey.h" // The ShapeManager handles the ref-counting on shared shapes://// Each object added to the physics simulation gets a corresponding btRigidBody.// The body has a btCollisionShape that represents the contours of its collision// surface.  Multiple bodies may have the same shape.  Rather than create a unique// btCollisionShape instance for every body with a particular shape we can instead// use a single shape instance for all of the bodies.  This is called "shape// sharing".//// When body needs a new shape a description of ths shape (ShapeInfo) is assembled// and a request is sent to the ShapeManager for a corresponding btCollisionShape// pointer.  The ShapeManager will compute a hash of the ShapeInfo's data and use// that to find the shape in its map.  If it finds one it increments the ref-count// and returns the pointer.  If not it asks the ShapeFactory to create it, adds an// entry in the map with a ref-count of 1, and returns the pointer.//// When a body stops using a shape the ShapeManager must be informed so it can// decrement its ref-count.  When a ref-count drops to zero the ShapeManager// doesn't delete it right away.  Instead it puts the shape's key on a list delete// later.  When that list grows big enough the ShapeManager will remove any matching// entries that still have zero ref-count.  class ShapeManager : public QObject {    Q_OBJECTpublic:     ShapeManager();    ~ShapeManager();     /// \return pointer to shape    const btCollisionShape* getShape(const ShapeInfo& info);    const btCollisionShape* getShapeByKey(uint64_t key);    bool hasShapeWithKey(uint64_t key) const;     /// \return true if shape was found and released    bool releaseShape(const btCollisionShape* shape);     /// delete shapes that have zero references    void collectGarbage();     // validation methods    int getNumShapes() const { return _shapeMap.size(); }    int getNumReferences(const ShapeInfo& info) const;    int getNumReferences(const btCollisionShape* shape) const;    bool hasShape(const btCollisionShape* shape) const;    uint32_t getWorkRequestCount() const { return _workRequestCount; }    uint32_t getWorkDeliveryCount() const { return _workDeliveryCount; } protected slots:    void acceptWork(ShapeFactory::Worker* worker); private:    void addToGarbage(uint64_t key);    bool releaseShapeByKey(uint64_t key);     class ShapeReference {    public:        int refCount;        const btCollisionShape* shape;        uint64_t key { 0 };        ShapeReference() : refCount(0), shape(nullptr) {}    };     using TimePoint = std::chrono::time_point<std::chrono::steady_clock>;    class KeyExpiry {    public:        KeyExpiry(uint64_t k, std::chrono::time_point<std::chrono::steady_clock> e) : expiry(e), key(k) {}        TimePoint expiry;        uint64_t key;    };     // btHashMap is required because it supports memory alignment of the btCollisionShapes    btHashMap<HashKey, ShapeReference> _shapeMap;    std::vector<uint64_t> _garbageRing;    std::vector<uint64_t> _pendingMeshShapes;    std::vector<KeyExpiry> _orphans;    ShapeFactory::Worker* _deadWorker { nullptr };    TimePoint _nextOrphanExpiry;    uint32_t _ringIndex { 0 };    std::atomic_uint _workRequestCount { 0 };    std::atomic_uint _workDeliveryCount { 0 };}; #endif // hifi_ShapeManager_h