add 'physics body count' to debug stats

interface/resources/qml/Stats.qml

@@ -60,6 +60,9 @@ Item {
                     StatText {
                         text: "Game Rate: " + root.gameLoopRate
                     }
+                    StatText {
+                        text: "Physics Body Count: " + root.physicsBodyCount
+                    }
                     StatText {
                         visible: root.expanded
                         text: root.gameUpdateStats

interface/src/Application.cpp

@@ -6184,6 +6184,10 @@ bool Application::isHMDMode() const {
     return getActiveDisplayPlugin()->isHmd();
 }
 
+float Application::getNumRigidBodies() const {
+    return _physicsEngine ? _physicsEngine->getNumRigidBodies() : 0;
+}
+
 float Application::getTargetRenderFrameRate() const { return getActiveDisplayPlugin()->getTargetFrameRate(); }
 
 QRect Application::getDesirableApplicationGeometry() const {

interface/src/Application.h

@@ -207,6 +207,7 @@ public:
 
     size_t getRenderFrameCount() const { return _renderFrameCount; }
     float getRenderLoopRate() const { return _renderLoopCounter.rate(); }
+    float getNumRigidBodies() const;
     float getTargetRenderFrameRate() const; // frames/second
 
     float getFieldOfView() { return _fieldOfView.get(); }

interface/src/ui/Stats.cpp

@@ -121,6 +121,7 @@ void Stats::updateStats(bool force) {
     auto avatarManager = DependencyManager::get<AvatarManager>();
     // we need to take one avatar out so we don't include ourselves
     STAT_UPDATE(avatarCount, avatarManager->size() - 1);
+    STAT_UPDATE(physicsBodyCount, qApp->getNumRigidBodies());
     STAT_UPDATE(updatedAvatarCount, avatarManager->getNumAvatarsUpdated());
     STAT_UPDATE(notUpdatedAvatarCount, avatarManager->getNumAvatarsNotUpdated());
     STAT_UPDATE(serverCount, (int)nodeList->size());

interface/src/ui/Stats.h

@@ -49,6 +49,7 @@ private: \
  * @property {number} presentdroprate - <em>Read-only.</em>
  * @property {number} gameLoopRate - <em>Read-only.</em>
  * @property {number} avatarCount - <em>Read-only.</em>
+ * @property {number} physicsBodyCount - <em>Read-only.</em>
  * @property {number} updatedAvatarCount - <em>Read-only.</em>
  * @property {number} notUpdatedAvatarCount - <em>Read-only.</em>
  * @property {number} packetInCount - <em>Read-only.</em>
@@ -195,6 +196,7 @@ class Stats : public QQuickItem {
     STATS_PROPERTY(float, presentdroprate, 0)
     STATS_PROPERTY(int, gameLoopRate, 0)
     STATS_PROPERTY(int, avatarCount, 0)
+    STATS_PROPERTY(int, physicsBodyCount, 0)
     STATS_PROPERTY(int, updatedAvatarCount, 0)
     STATS_PROPERTY(int, notUpdatedAvatarCount, 0)
     STATS_PROPERTY(int, packetInCount, 0)
@@ -406,6 +408,13 @@ signals:
      */
     void gameLoopRateChanged();
 
+    /**jsdoc
+     * Trigered when
+     * @function Stats.numPhysicsBodiesChanged
+     * @returns {Signal}
+     */
+    void physicsBodyCountChanged();
+
     /**jsdoc
      * Triggered when the value of the <code>avatarCount</code> property changes.
      * @function Stats.avatarCountChanged

libraries/physics/src/PhysicsEngine.cpp

@@ -93,6 +93,7 @@ void PhysicsEngine::addObjectToDynamicsWorld(ObjectMotionState* motionState) {
                 btCollisionShape* shape = const_cast<btCollisionShape*>(motionState->getShape());
                 assert(shape);
                 body = new btRigidBody(mass, motionState, shape, inertia);
+                ++_numRigidBodies;
                 motionState->setRigidBody(body);
             } else {
                 body->setMassProps(mass, inertia);
@@ -116,6 +117,7 @@ void PhysicsEngine::addObjectToDynamicsWorld(ObjectMotionState* motionState) {
             shape->calculateLocalInertia(mass, inertia);
             if (!body) {
                 body = new btRigidBody(mass, motionState, shape, inertia);
+                ++_numRigidBodies;
                 motionState->setRigidBody(body);
             } else {
                 body->setMassProps(mass, inertia);
@@ -139,6 +141,7 @@ void PhysicsEngine::addObjectToDynamicsWorld(ObjectMotionState* motionState) {
             if (!body) {
                 assert(motionState->getShape());
                 body = new btRigidBody(mass, motionState, const_cast<btCollisionShape*>(motionState->getShape()), inertia);
+                ++_numRigidBodies;
                 motionState->setRigidBody(body);
             } else {
                 body->setMassProps(mass, inertia);
@@ -206,6 +209,7 @@ void PhysicsEngine::removeObjects(const VectorOfMotionStates& objects) {
         if (body) {
             removeDynamicsForBody(body);
             _dynamicsWorld->removeRigidBody(body);
+            --_numRigidBodies;
 
             // NOTE: setRigidBody() modifies body->m_userPointer so we should clear the MotionState's body BEFORE deleting it.
             object->setRigidBody(nullptr);
@@ -223,6 +227,7 @@ void PhysicsEngine::removeSetOfObjects(const SetOfMotionStates& objects) {
         if (body) {
             removeDynamicsForBody(body);
             _dynamicsWorld->removeRigidBody(body);
+            --_numRigidBodies;
 
             // NOTE: setRigidBody() modifies body->m_userPointer so we should clear the MotionState's body BEFORE deleting it.
             object->setRigidBody(nullptr);
@@ -274,6 +279,7 @@ void PhysicsEngine::reinsertObject(ObjectMotionState* object) {
     btRigidBody* body = object->getRigidBody();
     if (body) {
         _dynamicsWorld->removeRigidBody(body);
+        --_numRigidBodies;
         // add it back
         addObjectToDynamicsWorld(object);
     }
@@ -286,6 +292,7 @@ void PhysicsEngine::processTransaction(PhysicsEngine::Transaction& transaction)
         if (body) {
             removeDynamicsForBody(body);
             _dynamicsWorld->removeRigidBody(body);
+            --_numRigidBodies;
 
             // NOTE: setRigidBody() modifies body->m_userPointer so we should clear the MotionState's body BEFORE deleting it.
             object->setRigidBody(nullptr);

libraries/physics/src/PhysicsEngine.h

@@ -143,6 +143,8 @@ public:
     // See PhysicsCollisionGroups.h for mask flags.
     std::vector<ContactTestResult> contactTest(uint16_t mask, const ShapeInfo& regionShapeInfo, const Transform& regionTransform, uint16_t group = USER_COLLISION_GROUP_DYNAMIC) const;
 
+    int32_t getNumRigidBodies() const { return _numRigidBodies; }
+
 private:
     QList<EntityDynamicPointer> removeDynamicsForBody(btRigidBody* body);
     void addObjectToDynamicsWorld(ObjectMotionState* motionState);
@@ -174,7 +176,8 @@ private:
 
     CharacterController* _myAvatarController;
 
-    uint32_t _numContactFrames = 0;
+    uint32_t _numContactFrames { 0 };
+    int32_t _numRigidBodies { 0 };
 
     bool _dumpNextStats { false };
     bool _saveNextStats { false };