From 806e691bbf2a9d5f249f4b4c1fc2727f4b97d1df Mon Sep 17 00:00:00 2001
From: ZappoMan <bradh@konamoxt.com>
Date: Wed, 7 Jan 2015 13:41:07 -0800
Subject: [PATCH] restore camera lookAt and keepLookingAt features

---
 .../example/avatarcontrol/lookAtExample.js    |  4 +-
 interface/src/Camera.cpp                      | 54 ++++++++++++++++---
 interface/src/Camera.h                        | 24 ++++++---
 3 files changed, 68 insertions(+), 14 deletions(-)

diff --git a/examples/example/avatarcontrol/lookAtExample.js b/examples/example/avatarcontrol/lookAtExample.js
index 087cd3fc90..e21341469d 100644
--- a/examples/example/avatarcontrol/lookAtExample.js
+++ b/examples/example/avatarcontrol/lookAtExample.js
@@ -22,7 +22,7 @@ var oldMode = Camera.mode;
 function cancelLookAt() {
     if (lookingAtSomething) {
         lookingAtSomething = false;
-        //Camera.stopLooking();
+        Camera.stopLooking();
         Camera.mode = oldMode;
         releaseMovementKeys();
     }
@@ -74,7 +74,7 @@ function mousePressEvent(event) {
             Camera.mode = "independent";
 
             // tell the camera to fix it's look at on the point we clicked
-            //Camera.keepLookingAt(intersection.intersection);
+            Camera.keepLookingAt(intersection.intersection);
 
             // keep track of the fact that we're in this looking at mode
             lookingAtSomething = true;
diff --git a/interface/src/Camera.cpp b/interface/src/Camera.cpp
index 313b7b7774..d08c59eb95 100644
--- a/interface/src/Camera.cpp
+++ b/interface/src/Camera.cpp
@@ -55,16 +55,44 @@ Camera::Camera() :
     _farClip(DEFAULT_FAR_CLIP), // default
     _hmdPosition(),
     _hmdRotation(),
-    _targetPosition(),
-    _targetRotation(),
-    _scale(1.0f)
+    _scale(1.0f),
+    _isKeepLookingAt(false),
+    _lookingAt(0.0f, 0.0f, 0.0f)
 {
 }
 
 void Camera::update(float deltaTime) {
+    if (_isKeepLookingAt) {
+        lookAt(_lookingAt);
+    }
     return;
 }
 
+void Camera::setPosition(const glm::vec3& position) {
+    _position = position; 
+}
+
+void Camera::setRotation(const glm::quat& rotation) {
+    _rotation = rotation; 
+    if (_isKeepLookingAt) {
+        lookAt(_lookingAt);
+    }
+}
+
+void Camera::setHmdPosition(const glm::vec3& hmdPosition) {
+    _hmdPosition = hmdPosition; 
+    if (_isKeepLookingAt) {
+        lookAt(_lookingAt);
+    }
+}
+
+void Camera::setHmdRotation(const glm::quat& hmdRotation) {
+    _hmdRotation = hmdRotation; 
+    if (_isKeepLookingAt) {
+        lookAt(_lookingAt);
+    }
+}
+
 float Camera::getFarClip() const {
     return (_scale * _farClip < std::numeric_limits<int16_t>::max())
             ? _scale * _farClip
@@ -81,15 +109,15 @@ void Camera::setFieldOfView(float f) {
     _fieldOfView = f; 
 }
 
-void Camera::setAspectRatio(float a) { 
+void Camera::setAspectRatio(float a) {
     _aspectRatio = a;
 }
 
-void Camera::setNearClip(float n) { 
+void Camera::setNearClip(float n) {
     _nearClip = n;
 }
 
-void Camera::setFarClip(float f) { 
+void Camera::setFarClip(float f) {
     _farClip = f;
 }
 
@@ -136,3 +164,17 @@ void Camera::setModeString(const QString& mode) {
 QString Camera::getModeString() const {
     return modeToString(_mode);
 }
+
+void Camera::lookAt(const glm::vec3& lookAt) {
+    glm::vec3 up = IDENTITY_UP;
+    glm::mat4 lookAtMatrix = glm::lookAt(_position, lookAt, up);
+    glm::quat rotation = glm::quat_cast(lookAtMatrix);
+    rotation.w = -rotation.w; // Rosedale approved
+    _rotation = rotation;
+}
+
+void Camera::keepLookingAt(const glm::vec3& point) {
+    lookAt(point);
+    _isKeepLookingAt = true;
+    _lookingAt = point;
+}
diff --git a/interface/src/Camera.h b/interface/src/Camera.h
index 7fcf9404cd..7c6951b920 100644
--- a/interface/src/Camera.h
+++ b/interface/src/Camera.h
@@ -43,9 +43,9 @@ public:
 
     void update( float deltaTime );
 
-    void setRotation(const glm::quat& rotation) { _rotation = rotation; };
-    void setHmdPosition(const glm::vec3& hmdPosition) { _hmdPosition = hmdPosition; }
-    void setHmdRotation(const glm::quat& hmdRotation) { _hmdRotation = hmdRotation; };
+    void setRotation(const glm::quat& rotation);
+    void setHmdPosition(const glm::vec3& hmdPosition);
+    void setHmdRotation(const glm::quat& hmdRotation);
     
     void setMode(CameraMode m);
     void setFieldOfView(float f);
@@ -73,13 +73,25 @@ public slots:
     void setModeString(const QString& mode);
 
     glm::vec3 getPosition() const { return _position + _hmdPosition; }
-    void setPosition(const glm::vec3& position) { _position = position; }
+    void setPosition(const glm::vec3& position);
     
     void setOrientation(const glm::quat& orientation) { setRotation(orientation); }
     glm::quat getOrientation() const { return getRotation(); }
     
     PickRay computePickRay(float x, float y);
     PickRay computeViewPickRay(float xRatio, float yRatio);
+
+    // These only work on independent cameras
+    /// one time change to what the camera is looking at
+    void lookAt(const glm::vec3& value);
+
+    /// fix what the camera is looking at, and keep the camera looking at this even if position changes
+    void keepLookingAt(const glm::vec3& value);
+
+    /// stops the keep looking at feature, doesn't change what's being looked at, but will stop camera from
+    /// continuing to update it's orientation to keep looking at the item
+    void stopLooking() { _isKeepLookingAt = false; }
+
 signals:
     void modeUpdated(const QString& newMode);
 
@@ -95,9 +107,9 @@ private:
     glm::quat _rotation;
     glm::vec3 _hmdPosition;
     glm::quat _hmdRotation;
-    glm::vec3 _targetPosition;
-    glm::quat _targetRotation;
     float _scale;
+    bool _isKeepLookingAt;
+    glm::vec3 _lookingAt;
 };
 
 #endif // hifi_Camera_h