From 99bd0f3d1341ce4bdee1049912d44b567796d92c Mon Sep 17 00:00:00 2001
From: "Anthony J. Thibault" <ajt@highfidelity.io>
Date: Mon, 29 Feb 2016 16:49:35 -0800
Subject: [PATCH] MyAvatar: fixes for eye look at

Users in desktop mode should now see the eyes change focus between the left eye, right eye and the mouth.
Users in mirror mode, or third person camera, should more accurately determine which avatar to look at.
---
 interface/src/avatar/MyAvatar.cpp | 40 ++++++++++++-------------------
 1 file changed, 15 insertions(+), 25 deletions(-)

diff --git a/interface/src/avatar/MyAvatar.cpp b/interface/src/avatar/MyAvatar.cpp
index fc715eebe9..1b04fa4fa4 100644
--- a/interface/src/avatar/MyAvatar.cpp
+++ b/interface/src/avatar/MyAvatar.cpp
@@ -849,7 +849,7 @@ void MyAvatar::updateLookAtTargetAvatar() {
         avatar->setIsLookAtTarget(false);
         if (!avatar->isMyAvatar() && avatar->isInitialized() &&
             (distanceTo < GREATEST_LOOKING_AT_DISTANCE * getUniformScale())) {
-            float angleTo = glm::angle(lookForward, glm::normalize(avatar->getHead()->getEyePosition() - cameraPosition));
+            float angleTo = glm::angle(lookForward, glm::normalize(avatar->getHead()->getEyePosition() - getHead()->getEyePosition()));
             if (angleTo < (smallestAngleTo * (isCurrentTarget ? KEEP_LOOKING_AT_CURRENT_ANGLE_FACTOR : 1.0f))) {
                 _lookAtTargetAvatar = avatarPointer;
                 _targetAvatarPosition = avatarPointer->getPosition();
@@ -864,36 +864,26 @@ void MyAvatar::updateLookAtTargetAvatar() {
                 // Let's get everything to world space:
                 glm::vec3 avatarLeftEye = getHead()->getLeftEyePosition();
                 glm::vec3 avatarRightEye = getHead()->getRightEyePosition();
-                // When not in HMD, these might both answer identity (i.e., the bridge of the nose). That's ok.
-                // By my inpsection of the code and live testing, getEyeOffset and getEyePose are the same. (Application hands identity as offset matrix.)
-                // This might be more work than needed for any given use, but as we explore different formulations, we go mad if we don't work in world space.
-                glm::mat4 leftEye = qApp->getEyeOffset(Eye::Left);
-                glm::mat4 rightEye = qApp->getEyeOffset(Eye::Right);
-                glm::vec3 leftEyeHeadLocal = glm::vec3(leftEye[3]);
-                glm::vec3 rightEyeHeadLocal = glm::vec3(rightEye[3]);
-                auto humanSystem = qApp->getViewFrustum();
-                glm::vec3 humanLeftEye = humanSystem->getPosition() + (humanSystem->getOrientation() * leftEyeHeadLocal);
-                glm::vec3 humanRightEye = humanSystem->getPosition() + (humanSystem->getOrientation() * rightEyeHeadLocal);
 
                 // First find out where (in world space) the person is looking relative to that bridge-of-the-avatar point.
                 // (We will be adding that offset to the camera position, after making some other adjustments.)
                 glm::vec3 gazeOffset = lookAtPosition - getHead()->getEyePosition();
 
-                // Scale by proportional differences between avatar and human.
-                float humanEyeSeparationInModelSpace = glm::length(humanLeftEye - humanRightEye);
-                float avatarEyeSeparation = glm::length(avatarLeftEye - avatarRightEye);
-                gazeOffset = gazeOffset * humanEyeSeparationInModelSpace / avatarEyeSeparation;
+                // scale gazeOffset by IPD, if wearing an HMD.
+                if (qApp->isHMDMode()) {
+                    glm::mat4 leftEye = qApp->getEyeOffset(Eye::Left);
+                    glm::mat4 rightEye = qApp->getEyeOffset(Eye::Right);
+                    glm::vec3 leftEyeHeadLocal = glm::vec3(leftEye[3]);
+                    glm::vec3 rightEyeHeadLocal = glm::vec3(rightEye[3]);
+                    auto humanSystem = qApp->getViewFrustum();
+                    glm::vec3 humanLeftEye = humanSystem->getPosition() + (humanSystem->getOrientation() * leftEyeHeadLocal);
+                    glm::vec3 humanRightEye = humanSystem->getPosition() + (humanSystem->getOrientation() * rightEyeHeadLocal);
 
-                // If the camera is also not oriented with the head, adjust by getting the offset in head-space...
-                /* Not needed (i.e., code is a no-op), but I'm leaving the example code here in case something like this is needed someday.
-                 glm::quat avatarHeadOrientation = getHead()->getOrientation();
-                 glm::vec3 gazeOffsetLocalToHead = glm::inverse(avatarHeadOrientation) * gazeOffset;
-                 // ... and treat that as though it were in camera space, bringing it back to world space.
-                 // But camera is fudged to make the picture feel like the avatar's orientation.
-                 glm::quat humanOrientation = humanSystem->getOrientation(); // or just avatar getOrienation() ?
-                 gazeOffset = humanOrientation * gazeOffsetLocalToHead;
-                 glm::vec3 corrected = humanSystem->getPosition() + gazeOffset;
-                 */
+                    // Scale by proportional differences between avatar and human.
+                    float humanEyeSeparationInModelSpace = glm::length(humanLeftEye - humanRightEye);
+                    float avatarEyeSeparation = glm::length(avatarLeftEye - avatarRightEye);
+                    gazeOffset = gazeOffset * humanEyeSeparationInModelSpace / avatarEyeSeparation;
+                }
 
                 // And now we can finally add that offset to the camera.
                 glm::vec3 corrected = qApp->getViewFrustum()->getPosition() + gazeOffset;