From 28978c8adbbba97b9b1064c889f19fc382144e47 Mon Sep 17 00:00:00 2001
From: Brad Hefta-Gaub <brad@highfidelity.io>
Date: Wed, 30 Mar 2016 17:49:30 -0700
Subject: [PATCH] optimize checkEnterLeaveEntities() to do distance check and
 stationary checks less frequently

---
 interface/src/Application.cpp                          |  4 +++-
 libraries/entities-renderer/src/EntityTreeRenderer.cpp | 10 ++++++++--
 libraries/entities-renderer/src/EntityTreeRenderer.h   |  4 ++++
 3 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/interface/src/Application.cpp b/interface/src/Application.cpp
index 781816a62a..12f343eba3 100644
--- a/interface/src/Application.cpp
+++ b/interface/src/Application.cpp
@@ -3347,9 +3347,10 @@ void Application::update(float deltaTime) {
         }
         {
             PROFILE_RANGE_EX("HarvestChanges", 0xffffff00, (uint64_t)getActiveDisplayPlugin()->presentCount());
-            PerformanceTimer perfTimer("havestChanges");
+            PerformanceTimer perfTimer("harvestChanges");
             if (_physicsEngine->hasOutgoingChanges()) {
                 getEntities()->getTree()->withWriteLock([&] {
+                    PerformanceTimer perfTimer("handleOutgoingChanges");
                     const VectorOfMotionStates& outgoingChanges = _physicsEngine->getOutgoingChanges();
                     _entitySimulation.handleOutgoingChanges(outgoingChanges, Physics::getSessionUUID());
                     avatarManager->handleOutgoingChanges(outgoingChanges);
@@ -3365,6 +3366,7 @@ void Application::update(float deltaTime) {
                     // Collision events (and their scripts) must not be handled when we're locked, above. (That would risk
                     // deadlock.)
                     _entitySimulation.handleCollisionEvents(collisionEvents);
+
                     // NOTE: the getEntities()->update() call below will wait for lock
                     // and will simulate entity motion (the EntityTree has been given an EntitySimulation).
                     getEntities()->update(); // update the models...
diff --git a/libraries/entities-renderer/src/EntityTreeRenderer.cpp b/libraries/entities-renderer/src/EntityTreeRenderer.cpp
index 65ac5197c8..4078e24076 100644
--- a/libraries/entities-renderer/src/EntityTreeRenderer.cpp
+++ b/libraries/entities-renderer/src/EntityTreeRenderer.cpp
@@ -130,6 +130,7 @@ void EntityTreeRenderer::setTree(OctreePointer newTree) {
 }
 
 void EntityTreeRenderer::update() {
+    PerformanceTimer perfTimer("ETRupdate");
     if (_tree && !_shuttingDown) {
         EntityTreePointer tree = std::static_pointer_cast<EntityTree>(_tree);
         tree->update();
@@ -158,6 +159,7 @@ void EntityTreeRenderer::update() {
 }
 
 bool EntityTreeRenderer::findBestZoneAndMaybeContainingEntities(const glm::vec3& avatarPosition, QVector<EntityItemID>* entitiesContainingAvatar) {
+    PerformanceTimer perfTimer("findBestZone");
     bool didUpdate = false;
     float radius = 1.0f; // for now, assume 1 meter radius
     QVector<EntityItemPointer> foundEntities;
@@ -218,12 +220,15 @@ bool EntityTreeRenderer::findBestZoneAndMaybeContainingEntities(const glm::vec3&
     return didUpdate;
 }
 bool EntityTreeRenderer::checkEnterLeaveEntities() {
+    PerformanceTimer perfTimer("checkEnterLeaveEntities");
+    auto now = usecTimestampNow();
     bool didUpdate = false;
 
     if (_tree && !_shuttingDown) {
         glm::vec3 avatarPosition = _viewState->getAvatarPosition();
 
-        if (avatarPosition != _lastAvatarPosition) {
+        // If we've moved "enough" check to see our enter/leave state
+        if (glm::distance(avatarPosition, _lastAvatarPosition) > ZONE_CHECK_DISTANCE) {
             QVector<EntityItemID> entitiesContainingAvatar;
             didUpdate = findBestZoneAndMaybeContainingEntities(avatarPosition, &entitiesContainingAvatar);
             
@@ -248,7 +253,8 @@ bool EntityTreeRenderer::checkEnterLeaveEntities() {
             }
             _currentEntitiesInside = entitiesContainingAvatar;
             _lastAvatarPosition = avatarPosition;
-        } else {
+        } else if ((now - _lastZoneCheck) > ZONE_CHECK_INTERVAL) { // if it's been a while since checking zone state
+            _lastZoneCheck = now;
             didUpdate = findBestZoneAndMaybeContainingEntities(avatarPosition, nullptr);
         }
     }
diff --git a/libraries/entities-renderer/src/EntityTreeRenderer.h b/libraries/entities-renderer/src/EntityTreeRenderer.h
index 095723dc9a..0fd5adc3f0 100644
--- a/libraries/entities-renderer/src/EntityTreeRenderer.h
+++ b/libraries/entities-renderer/src/EntityTreeRenderer.h
@@ -178,6 +178,10 @@ private:
     std::shared_ptr<ZoneEntityItem> _bestZone;
     float _bestZoneVolume;
 
+    quint64 _lastZoneCheck { 0 };
+    const quint64 ZONE_CHECK_INTERVAL = USECS_PER_MSEC * 100; // ~10hz
+    const float ZONE_CHECK_DISTANCE = 0.001f;
+
     glm::vec3 _previousKeyLightColor;
     float _previousKeyLightIntensity;
     float _previousKeyLightAmbientIntensity;