From 42a4fd8884604a6af192bffa4517d5877cedc744 Mon Sep 17 00:00:00 2001
From: David Rowe <david@ctrlaltstudio.com>
Date: Wed, 29 Apr 2015 22:07:10 -0700
Subject: [PATCH] Add velocity filtering of DDE eyebrows

---
 interface/src/devices/DdeFaceTracker.cpp | 22 +++++++++++++++++-----
 interface/src/devices/DdeFaceTracker.h   |  2 ++
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/interface/src/devices/DdeFaceTracker.cpp b/interface/src/devices/DdeFaceTracker.cpp
index be25c0794d..d6cc644db1 100644
--- a/interface/src/devices/DdeFaceTracker.cpp
+++ b/interface/src/devices/DdeFaceTracker.cpp
@@ -169,7 +169,9 @@ DdeFaceTracker::DdeFaceTracker(const QHostAddress& host, quint16 serverPort, qui
     _lastLeftEyeBlink(0.0f),
     _filteredLeftEyeBlink(0.0f),
     _lastRightEyeBlink(0.0f),
-    _filteredRightEyeBlink(0.0f)
+    _filteredRightEyeBlink(0.0f),
+    _lastBrowUp(0.0f),
+    _filteredBrowUp(0.0f)
 {
     _coefficients.resize(NUM_FACESHIFT_BLENDSHAPES);
 
@@ -389,10 +391,20 @@ void DdeFaceTracker::decodePacket(const QByteArray& buffer) {
         }
 
         // Use BrowsU_C to control both brows' up and down
-        _coefficients[_browDownLeftIndex] = -_coefficients[_browUpCenterIndex];
-        _coefficients[_browDownRightIndex] = -_coefficients[_browUpCenterIndex];
-        _coefficients[_browUpLeftIndex] = _coefficients[_browUpCenterIndex];
-        _coefficients[_browUpRightIndex] = _coefficients[_browUpCenterIndex];
+        float browUp = _coefficients[_browUpCenterIndex];
+        if (isFiltering) {
+            const float BROW_VELOCITY_FILTER_STRENGHT = 0.8f;
+            float velocity = fabs(browUp - _lastBrowUp) / _averageMessageTime;
+            float velocityFilter = glm::clamp(velocity * BROW_VELOCITY_FILTER_STRENGHT, 0.0f, 1.0f);
+            _filteredBrowUp = velocityFilter * browUp + (1.0f - velocityFilter) * _filteredBrowUp;
+            _lastBrowUp = browUp;
+            browUp = _filteredBrowUp;
+            _coefficients[_browUpCenterIndex] = browUp;
+        }
+        _coefficients[_browUpLeftIndex] = browUp;
+        _coefficients[_browUpRightIndex] = browUp;
+        _coefficients[_browDownLeftIndex] = -browUp;
+        _coefficients[_browDownRightIndex] = -browUp;
 
         // Offset jaw open coefficient
         static const float JAW_OPEN_THRESHOLD = 0.16f;
diff --git a/interface/src/devices/DdeFaceTracker.h b/interface/src/devices/DdeFaceTracker.h
index d9df5723cf..d4572c8430 100644
--- a/interface/src/devices/DdeFaceTracker.h
+++ b/interface/src/devices/DdeFaceTracker.h
@@ -109,6 +109,8 @@ private:
     float _filteredLeftEyeBlink;
     float _lastRightEyeBlink;
     float _filteredRightEyeBlink;
+    float _lastBrowUp;
+    float _filteredBrowUp;
 };
 
 #endif // hifi_DdeFaceTracker_h
\ No newline at end of file