From a11bf7f15ba2f7810f3837713a3fc9dba4c7b4db Mon Sep 17 00:00:00 2001
From: David Rowe <david@ctrlaltstudio.com>
Date: Fri, 19 Sep 2014 14:26:44 -0700
Subject: [PATCH] Decouple Rift head tracking from avatar's head position

This makes the Rift's view reflect the user's physical movements exactly
while the avatar follows the movements as best it can.
---
 interface/src/Application.cpp          | 2 +-
 interface/src/avatar/Avatar.cpp        | 4 ----
 interface/src/avatar/Avatar.h          | 1 -
 interface/src/avatar/MyAvatar.cpp      | 2 +-
 interface/src/avatar/SkeletonModel.cpp | 7 +++++++
 interface/src/avatar/SkeletonModel.h   | 6 ++++++
 6 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/interface/src/Application.cpp b/interface/src/Application.cpp
index a20a6553d4..00cf3b9d01 100644
--- a/interface/src/Application.cpp
+++ b/interface/src/Application.cpp
@@ -682,7 +682,7 @@ void Application::paintGL() {
         if (whichCamera.getMode() == CAMERA_MODE_MIRROR) {
             OculusManager::display(whichCamera.getRotation(), whichCamera.getPosition(), whichCamera);
         } else {
-            OculusManager::display(_myAvatar->getWorldAlignedOrientation(), whichCamera.getPosition(), whichCamera);
+            OculusManager::display(_myAvatar->getWorldAlignedOrientation(), _myAvatar->getUprightHeadPosition(), whichCamera);
         }
 
     } else if (TV3DManager::isConnected()) {
diff --git a/interface/src/avatar/Avatar.cpp b/interface/src/avatar/Avatar.cpp
index 6f421965db..22e7697b40 100644
--- a/interface/src/avatar/Avatar.cpp
+++ b/interface/src/avatar/Avatar.cpp
@@ -1028,10 +1028,6 @@ float Avatar::getPelvisFloatingHeight() const {
     return -_skeletonModel.getBindExtents().minimum.y;
 }
 
-float Avatar::getPelvisToHeadLength() const {
-    return glm::distance(_position, getHead()->getPosition());
-}
-
 void Avatar::setShowDisplayName(bool showDisplayName) {
     if (!Menu::getInstance()->isOptionChecked(MenuOption::NamesAboveHeads)) {
         _displayNameAlpha = 0.0f;
diff --git a/interface/src/avatar/Avatar.h b/interface/src/avatar/Avatar.h
index c449a0d1b9..58add5aecd 100755
--- a/interface/src/avatar/Avatar.h
+++ b/interface/src/avatar/Avatar.h
@@ -223,7 +223,6 @@ protected:
     float getSkeletonHeight() const;
     float getHeadHeight() const;
     float getPelvisFloatingHeight() const;
-    float getPelvisToHeadLength() const;
     glm::vec3 getDisplayNamePosition();
 
     void renderDisplayName();
diff --git a/interface/src/avatar/MyAvatar.cpp b/interface/src/avatar/MyAvatar.cpp
index 27f74f185d..e59de3628a 100644
--- a/interface/src/avatar/MyAvatar.cpp
+++ b/interface/src/avatar/MyAvatar.cpp
@@ -977,7 +977,7 @@ void MyAvatar::clearLookAtTargetAvatar() {
 }
 
 glm::vec3 MyAvatar::getUprightHeadPosition() const {
-    return _position + getWorldAlignedOrientation() * glm::vec3(0.0f, getPelvisToHeadLength(), 0.0f);
+    return _position + getWorldAlignedOrientation() * _skeletonModel.getDefaultHeadModelPosition();
 }
 
 const float SCRIPT_PRIORITY = DEFAULT_PRIORITY + 1.0f;
diff --git a/interface/src/avatar/SkeletonModel.cpp b/interface/src/avatar/SkeletonModel.cpp
index 86ca42b15e..2e53412be4 100644
--- a/interface/src/avatar/SkeletonModel.cpp
+++ b/interface/src/avatar/SkeletonModel.cpp
@@ -656,6 +656,13 @@ void SkeletonModel::buildShapes() {
     // This method moves the shapes to their default positions in Model frame.
     computeBoundingShape(geometry);
 
+    int headJointIndex = _geometry->getFBXGeometry().headJointIndex;
+    if (0 <= headJointIndex && headJointIndex < _jointStates.size()) {
+        getJointPosition(headJointIndex, _defaultHeadModelPosition);
+    } else {
+        _defaultHeadModelPosition = glm::vec3(0.f, 0.f, 0.f);
+    }
+
     // While the shapes are in their default position we disable collisions between
     // joints that are currently colliding.
     disableCurrentSelfCollisions();
diff --git a/interface/src/avatar/SkeletonModel.h b/interface/src/avatar/SkeletonModel.h
index ca0007ddb4..036811a926 100644
--- a/interface/src/avatar/SkeletonModel.h
+++ b/interface/src/avatar/SkeletonModel.h
@@ -97,6 +97,10 @@ public:
     /// \return whether or not both eye meshes were found
     bool getEyePositions(glm::vec3& firstEyePosition, glm::vec3& secondEyePosition) const;
 
+    /// Gets the default position of the head in model frame coordinates.
+    /// \return whether or not the head was found.
+    glm::vec3 getDefaultHeadModelPosition() const { return _defaultHeadModelPosition; }
+
     virtual void updateVisibleJointStates();
 
     SkeletonRagdoll* buildRagdoll();
@@ -146,6 +150,8 @@ private:
     CapsuleShape _boundingShape;
     glm::vec3 _boundingShapeLocalOffset;
     SkeletonRagdoll* _ragdoll;
+
+    glm::vec3 _defaultHeadModelPosition;
 };
 
 #endif // hifi_SkeletonModel_h