From 93a5bdd79a6dc27abe8f6123490b44f737fc068f Mon Sep 17 00:00:00 2001
From: "Anthony J. Thibault" <tony@highfidelity.io>
Date: Fri, 8 Apr 2016 15:27:43 -0700
Subject: [PATCH] Prevent avatar rotation due to HMD head turning in
 third-person camera.

Also, fix one frame glitch during snap turning, by updating the sensorToWorld matrix
after the MyAvatar::updateOrientation rotates the avatar, but before we perform IK.
---
 interface/src/Application.cpp     |  3 ---
 interface/src/avatar/MyAvatar.cpp | 25 ++++++++++++++++---------
 2 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/interface/src/Application.cpp b/interface/src/Application.cpp
index a6555352dd..daf83d7a52 100644
--- a/interface/src/Application.cpp
+++ b/interface/src/Application.cpp
@@ -3490,9 +3490,6 @@ void Application::update(float deltaTime) {
             avatarManager->updateOtherAvatars(deltaTime);
         }
 
-        // update sensorToWorldMatrix for camera and hand controllers
-        getMyAvatar()->updateSensorToWorldMatrix();
-
         qApp->updateMyAvatarLookAtPosition();
 
         {
diff --git a/interface/src/avatar/MyAvatar.cpp b/interface/src/avatar/MyAvatar.cpp
index 6aa6f57e07..906f7b4c9f 100644
--- a/interface/src/avatar/MyAvatar.cpp
+++ b/interface/src/avatar/MyAvatar.cpp
@@ -294,20 +294,18 @@ void MyAvatar::update(float deltaTime) {
     auto audio = DependencyManager::get<AudioClient>();
     head->setAudioLoudness(audio->getLastInputLoudness());
     head->setAudioAverageLoudness(audio->getAudioAverageInputLoudness());
-    
-     simulate(deltaTime);
-    
+
+    simulate(deltaTime);
+
     currentEnergy += energyChargeRate;
     currentEnergy -= getAccelerationEnergy();
     currentEnergy -= getAudioEnergy();
-    
+
     if(didTeleport()) {
         currentEnergy = 0.0f;
     }
     currentEnergy = max(0.0f, min(currentEnergy,1.0f));
     emit energyChanged(currentEnergy);
-     
-   
 }
 
 extern QByteArray avatarStateToFrame(const AvatarData* _avatar);
@@ -333,6 +331,10 @@ void MyAvatar::simulate(float deltaTime) {
         updatePosition(deltaTime);
     }
 
+    // update sensorToWorldMatrix for camera and hand controllers
+    // before we perform rig animations and IK.
+    updateSensorToWorldMatrix();
+
     {
         PerformanceTimer perfTimer("skeleton");
         _skeletonModel->simulate(deltaTime);
@@ -1975,9 +1977,14 @@ void MyAvatar::FollowHelper::decrementTimeRemaining(float dt) {
 }
 
 bool MyAvatar::FollowHelper::shouldActivateRotation(const MyAvatar& myAvatar, const glm::mat4& desiredBodyMatrix, const glm::mat4& currentBodyMatrix) const {
-    const float FOLLOW_ROTATION_THRESHOLD = cosf(PI / 6.0f); // 30 degrees
-    glm::vec2 bodyFacing = getFacingDir2D(currentBodyMatrix);
-    return glm::dot(myAvatar.getHMDSensorFacingMovingAverage(), bodyFacing) < FOLLOW_ROTATION_THRESHOLD;
+    auto cameraMode = qApp->getCamera()->getMode();
+    if (cameraMode == CAMERA_MODE_THIRD_PERSON) {
+        return false;
+    } else {
+        const float FOLLOW_ROTATION_THRESHOLD = cosf(PI / 6.0f); // 30 degrees
+        glm::vec2 bodyFacing = getFacingDir2D(currentBodyMatrix);
+        return glm::dot(myAvatar.getHMDSensorFacingMovingAverage(), bodyFacing) < FOLLOW_ROTATION_THRESHOLD;
+    }
 }
 
 bool MyAvatar::FollowHelper::shouldActivateHorizontal(const MyAvatar& myAvatar, const glm::mat4& desiredBodyMatrix, const glm::mat4& currentBodyMatrix) const {