From b5537304a3366c08ee30bb69cacbb0b2cba57852 Mon Sep 17 00:00:00 2001
From: Andrew Meadows <andrew@highfidelity.io>
Date: Tue, 10 Jan 2017 21:29:08 -0800
Subject: [PATCH] more correct CONTINUE collision event filter

---
 libraries/physics/src/ContactInfo.cpp   | 14 ++++++++++++--
 libraries/physics/src/ContactInfo.h     |  4 +++-
 libraries/physics/src/PhysicsEngine.cpp |  5 ++---
 3 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/libraries/physics/src/ContactInfo.cpp b/libraries/physics/src/ContactInfo.cpp
index 59948db671..085f746a73 100644
--- a/libraries/physics/src/ContactInfo.cpp
+++ b/libraries/physics/src/ContactInfo.cpp
@@ -18,10 +18,20 @@ void ContactInfo::update(uint32_t currentStep, const btManifoldPoint& p) {
     distance = p.m_distance1;
 }
 
+const uint32_t STEPS_BETWEEN_CONTINUE_EVENTS = 9;
+
 ContactEventType ContactInfo::computeType(uint32_t thisStep) {
-    ++_numChecks;
-    if (_numChecks == 1) {
+    if (_continueExpiry == 0) {
+        _continueExpiry = thisStep + STEPS_BETWEEN_CONTINUE_EVENTS;
         return CONTACT_EVENT_TYPE_START;
     }
     return (_lastStep == thisStep) ? CONTACT_EVENT_TYPE_CONTINUE : CONTACT_EVENT_TYPE_END;
 }
+
+bool ContactInfo::readyForContinue(uint32_t thisStep) {
+    if (thisStep > _continueExpiry) {
+        _continueExpiry = thisStep + STEPS_BETWEEN_CONTINUE_EVENTS;
+        return true;
+    }
+    return false;
+}
diff --git a/libraries/physics/src/ContactInfo.h b/libraries/physics/src/ContactInfo.h
index 17356969d1..8d05f73b61 100644
--- a/libraries/physics/src/ContactInfo.h
+++ b/libraries/physics/src/ContactInfo.h
@@ -26,12 +26,14 @@ public:
     const btVector3& getPositionWorldOnB() const { return positionWorldOnB; }
     btVector3 getPositionWorldOnA() const { return positionWorldOnB + normalWorldOnB * distance; }
 
+    bool readyForContinue(uint32_t thisStep);
+
     btVector3 positionWorldOnB;
     btVector3 normalWorldOnB;
     btScalar distance;
 private:
     uint32_t _lastStep { 0 };
-    uint32_t _numChecks { 0 };
+    uint32_t _continueExpiry { 0 };
 };
 
 
diff --git a/libraries/physics/src/PhysicsEngine.cpp b/libraries/physics/src/PhysicsEngine.cpp
index 5b638b9a98..72596cb599 100644
--- a/libraries/physics/src/PhysicsEngine.cpp
+++ b/libraries/physics/src/PhysicsEngine.cpp
@@ -270,7 +270,7 @@ void PhysicsEngine::stepSimulation() {
     }
 
     auto onSubStep = [this]() {
-        updateContactMap();
+        this->updateContactMap();
     };
 
     int numSubsteps = _dynamicsWorld->stepSimulationWithSubstepCallback(timeStep, PHYSICS_ENGINE_MAX_NUM_SUBSTEPS,
@@ -393,7 +393,6 @@ void PhysicsEngine::updateContactMap() {
 }
 
 const CollisionEvents& PhysicsEngine::getCollisionEvents() {
-    const uint32_t CONTINUE_EVENT_FILTER_FREQUENCY = 10;
     _collisionEvents.clear();
 
     // scan known contacts and trigger events
@@ -402,7 +401,7 @@ const CollisionEvents& PhysicsEngine::getCollisionEvents() {
     while (contactItr != _contactMap.end()) {
         ContactInfo& contact = contactItr->second;
         ContactEventType type = contact.computeType(_numContactFrames);
-        if (type != CONTACT_EVENT_TYPE_CONTINUE || _numSubsteps % CONTINUE_EVENT_FILTER_FREQUENCY == 0) {
+        if (type != CONTACT_EVENT_TYPE_CONTINUE || contact.readyForContinue(_numContactFrames)) {
             ObjectMotionState* motionStateA = static_cast<ObjectMotionState*>(contactItr->first._a);
             ObjectMotionState* motionStateB = static_cast<ObjectMotionState*>(contactItr->first._b);