From 0154c613d0af2f8c806e70026b7c21dc41788943 Mon Sep 17 00:00:00 2001
From: Andrew Meadows <andrew@highfidelity.io>
Date: Tue, 20 Jan 2015 11:02:48 -0800
Subject: [PATCH] change FrameCount to NumSubsteps for more accuracy

---
 libraries/physics/src/KinematicController.cpp |  4 ++--
 libraries/physics/src/KinematicController.h   |  2 +-
 libraries/physics/src/PhysicsEngine.cpp       | 24 ++++++++++++-------
 libraries/physics/src/PhysicsEngine.h         |  4 +++-
 .../src/SimpleEntityKinematicController.cpp   |  6 ++---
 5 files changed, 24 insertions(+), 16 deletions(-)

diff --git a/libraries/physics/src/KinematicController.cpp b/libraries/physics/src/KinematicController.cpp
index abcf669694..354b285bc1 100644
--- a/libraries/physics/src/KinematicController.cpp
+++ b/libraries/physics/src/KinematicController.cpp
@@ -13,10 +13,10 @@
 #include "PhysicsEngine.h"
 
 KinematicController::KinematicController() { 
-    _lastFrame = PhysicsEngine::getFrameCount(); 
+    _lastSubstep = PhysicsEngine::getNumSubsteps(); 
 }
 
 void KinematicController::start() { 
     _enabled = true; 
-    _lastFrame = PhysicsEngine::getFrameCount(); 
+    _lastSubstep = PhysicsEngine::getNumSubsteps(); 
 }
diff --git a/libraries/physics/src/KinematicController.h b/libraries/physics/src/KinematicController.h
index 382d4cbfd9..60b8548607 100644
--- a/libraries/physics/src/KinematicController.h
+++ b/libraries/physics/src/KinematicController.h
@@ -30,7 +30,7 @@ public:
 
 protected:
     bool _enabled = false;
-    uint32_t _lastFrame;
+    uint32_t _lastSubstep;
 };
 
 #endif // hifi_KinematicController_h
diff --git a/libraries/physics/src/PhysicsEngine.cpp b/libraries/physics/src/PhysicsEngine.cpp
index ca64184bd7..af4a49aefe 100644
--- a/libraries/physics/src/PhysicsEngine.cpp
+++ b/libraries/physics/src/PhysicsEngine.cpp
@@ -13,11 +13,11 @@
 #include "ShapeInfoUtil.h"
 #include "ThreadSafeDynamicsWorld.h"
 
-static uint32_t _frameCount;
+static uint32_t _numSubsteps;
 
 // static
-uint32_t PhysicsEngine::getFrameCount() {
-    return _frameCount;
+uint32_t PhysicsEngine::getNumSubsteps() {
+    return _numSubsteps;
 }
 
 PhysicsEngine::PhysicsEngine(const glm::vec3& offset)
@@ -47,8 +47,8 @@ void PhysicsEngine::updateEntitiesInternal(const quint64& now) {
         ObjectMotionState* state = *stateItr;
         if (state->doesNotNeedToSendUpdate()) {
             stateItr = _outgoingPackets.erase(stateItr);
-        } else if (state->shouldSendUpdate(_frameCount)) {
-            state->sendUpdate(_entityPacketSender, _frameCount);
+        } else if (state->shouldSendUpdate(_numSubsteps)) {
+            state->sendUpdate(_entityPacketSender, _numSubsteps);
             ++stateItr;
         } else {
             ++stateItr;
@@ -141,7 +141,7 @@ void PhysicsEngine::relayIncomingChangesToSimulation() {
             } else if (flags) {
                 // an EASY update does NOT require that the body be pulled out of physics engine
                 // hence the MotionState has all the knowledge and authority to perform the update.
-                motionState->updateObjectEasy(flags, _frameCount);
+                motionState->updateObjectEasy(flags, _numSubsteps);
             }
         }
 
@@ -216,8 +216,8 @@ void PhysicsEngine::stepSimulation() {
     float timeStep = btMin(dt, MAX_TIMESTEP);
 
     // This is step (2).
-    int numSubSteps = _dynamicsWorld->stepSimulation(timeStep, MAX_NUM_SUBSTEPS, PHYSICS_ENGINE_FIXED_SUBSTEP);
-    _frameCount += (uint32_t)numSubSteps;
+    int numSubsteps = _dynamicsWorld->stepSimulation(timeStep, MAX_NUM_SUBSTEPS, PHYSICS_ENGINE_FIXED_SUBSTEP);
+    _numSubsteps += (uint32_t)numSubsteps;
     unlock();
 
     // This is step (3) which is done outside of stepSimulation() so we can lock _entityTree.
@@ -233,6 +233,12 @@ void PhysicsEngine::stepSimulation() {
     _dynamicsWorld->synchronizeMotionStates();
     unlock();
     _entityTree->unlock();
+
+    handleCollisionEvents();
+}
+
+void PhysicsEngine::handleCollisionEvents() {
+
 }
 
 // Bullet collision flags are as follows:
@@ -352,7 +358,7 @@ void PhysicsEngine::updateObjectHard(btRigidBody* body, ObjectMotionState* motio
     }
     bool easyUpdate = flags & EASY_DIRTY_PHYSICS_FLAGS;
     if (easyUpdate) {
-        motionState->updateObjectEasy(flags, _frameCount);
+        motionState->updateObjectEasy(flags, _numSubsteps);
     }
 
     // update the motion parameters
diff --git a/libraries/physics/src/PhysicsEngine.h b/libraries/physics/src/PhysicsEngine.h
index f37f12ea8d..7304f598e2 100644
--- a/libraries/physics/src/PhysicsEngine.h
+++ b/libraries/physics/src/PhysicsEngine.h
@@ -33,7 +33,7 @@ class ObjectMotionState;
 
 class PhysicsEngine : public EntitySimulation {
 public:
-    static uint32_t getFrameCount();
+    static uint32_t getNumSubsteps();
 
     PhysicsEngine(const glm::vec3& offset);
 
@@ -51,6 +51,8 @@ public:
 
     void stepSimulation();
 
+    void handleCollisionEvents();
+
     /// \param offset position of simulation origin in domain-frame
     void setOriginOffset(const glm::vec3& offset) { _originOffset = offset; }
 
diff --git a/libraries/physics/src/SimpleEntityKinematicController.cpp b/libraries/physics/src/SimpleEntityKinematicController.cpp
index 478ec1d12f..e834d4e91b 100644
--- a/libraries/physics/src/SimpleEntityKinematicController.cpp
+++ b/libraries/physics/src/SimpleEntityKinematicController.cpp
@@ -13,9 +13,9 @@
 #include "SimpleEntityKinematicController.h"
 
 void SimpleEntityKinematicController:: stepForward() {
-    uint32_t frame = PhysicsEngine::getFrameCount();
-    float dt = (frame - _lastFrame) * PHYSICS_ENGINE_FIXED_SUBSTEP;
+    uint32_t substep = PhysicsEngine::getNumSubsteps();
+    float dt = (substep - _lastSubstep) * PHYSICS_ENGINE_FIXED_SUBSTEP;
     _entity->simulateSimpleKinematicMotion(dt);
-    _lastFrame = frame;
+    _lastSubstep = substep;
 }