diff --git a/interface/src/devices/FaceTracker.cpp b/interface/src/devices/FaceTracker.cpp
index 52fe04de77..8d61789715 100644
--- a/interface/src/devices/FaceTracker.cpp
+++ b/interface/src/devices/FaceTracker.cpp
@@ -11,7 +11,6 @@
 
 #include "FaceTracker.h"
 
-FaceTracker::FaceTracker() :
-    _estimatedEyePitch(0.0f),
-    _estimatedEyeYaw(0.0f) {
+inline float FaceTracker::getBlendshapeCoefficient(int index) const {
+    return isValidBlendshapeIndex(index) ? _blendshapeCoefficients[index] : 0.0f;
 }
diff --git a/interface/src/devices/FaceTracker.h b/interface/src/devices/FaceTracker.h
index 7c367b7899..07c479e3e3 100644
--- a/interface/src/devices/FaceTracker.h
+++ b/interface/src/devices/FaceTracker.h
@@ -18,13 +18,17 @@
 #include <glm/glm.hpp>
 #include <glm/gtc/quaternion.hpp>
 
-/// Base class for face trackers (Faceshift, Visage).
+/// Base class for face trackers (Faceshift, Visage, DDE).
 class FaceTracker : public QObject {
     Q_OBJECT
     
 public:
-    FaceTracker();
-    virtual ~FaceTracker() {}
+    virtual bool isActive() const { return false; }
+    virtual bool isTracking() const { return false; }
+    
+    virtual void init() {}
+    virtual void update(float deltaTime) {}
+    virtual void reset() {}
     
     const glm::vec3& getHeadTranslation() const { return _headTranslation; }
     const glm::quat& getHeadRotation() const { return _headRotation; }
@@ -32,15 +36,21 @@ public:
     float getEstimatedEyePitch() const { return _estimatedEyePitch; }
     float getEstimatedEyeYaw() const { return _estimatedEyeYaw; } 
     
+    int getNumBlendshapes() const { return _blendshapeCoefficients.size(); }
+    bool isValidBlendshapeIndex(int index) const { return index >= 0 && index < getNumBlendshapes(); }
     const QVector<float>& getBlendshapeCoefficients() const { return _blendshapeCoefficients; }
+    float getBlendshapeCoefficient(int index) const;
     
 protected:
     
-    glm::vec3 _headTranslation;
-    glm::quat _headRotation;
-    float _estimatedEyePitch;
-    float _estimatedEyeYaw;
+    
+    glm::vec3 _headTranslation = glm::vec3(0.0f);
+    glm::quat _headRotation = glm::quat();
+    float _estimatedEyePitch = 0.0f;
+    float _estimatedEyeYaw = 0.0f;
     QVector<float> _blendshapeCoefficients;
+    
+    float _fadeCoefficient = 0.0f;
 };
 
 #endif // hifi_FaceTracker_h