expose avatar sort coefficients for fine tuning

interface/src/avatar/AvatarManager.cpp

@@ -204,14 +204,17 @@ void AvatarManager::updateOtherAvatars(float deltaTime) {
             float distance = glm::length(offset) + 0.001f; // add 1mm to avoid divide by zero
             float radius = avatar->getBoundingRadius();
             const glm::vec3& forward = cameraView.getDirection();
-            float apparentSize = radius / distance;
+            float apparentSize = 2.0f * radius / distance;
             float cosineAngle = glm::length(glm::dot(offset, forward) * forward) / distance;
             float age = (float)(startTime - avatar->getLastRenderUpdateTime()) / (float)(USECS_PER_SECOND);
+
             // NOTE: we are adding values of different units to get a single measure of "priority".
-            // Thus we multiply each component by a conversion "weight" that scales its units
-            // relative to the others.  These weights are pure magic tuning and are hard coded in the
-            // relation below: (hint: unitary weights are not explicityly shown)
-            float priority = apparentSize + 0.25f * cosineAngle + age;
+            // Thus we multiply each component by a conversion "weight" that scales its units relative to the others.
+            // These weights are pure magic tuning and should be hard coded in the relation below,
+            // but are currently exposed for anyone who would like to explore fine tuning:
+            float priority = _avatarSortCoefficientSize * apparentSize
+                    + _avatarSortCoefficientCenter * cosineAngle
+                    + _avatarSortCoefficientAge * age;
 
             // decrement priority of avatars outside keyhole
             if (distance > cameraView.getCenterRadius()) {
@@ -591,3 +594,29 @@ RayToAvatarIntersectionResult AvatarManager::findRayIntersection(const PickRay&
 
     return result;
 }
+
+// HACK
+float AvatarManager::getAvatarSortCoefficient(const QString& name) {
+    if (name == "size") {
+        return _avatarSortCoefficientSize;
+    } else if (name == "center") {
+        return _avatarSortCoefficientCenter;
+    } else if (name == "age") {
+        return _avatarSortCoefficientAge;
+    }
+    return 0.0f;
+}
+
+// HACK
+void AvatarManager::setAvatarSortCoefficient(const QString& name, const QScriptValue& value) {
+    if (value.isNumber()) {
+        float numericalValue = (float)value.toNumber();
+        if (name == "size") {
+            _avatarSortCoefficientSize = numericalValue;
+        } else if (name == "center") {
+            _avatarSortCoefficientCenter = numericalValue;
+        } else if (name == "age") {
+            _avatarSortCoefficientAge = numericalValue;
+        }
+    }
+}

interface/src/avatar/AvatarManager.h

@@ -81,6 +81,10 @@ public:
                                                                   const QScriptValue& avatarIdsToInclude = QScriptValue(),
                                                                   const QScriptValue& avatarIdsToDiscard = QScriptValue());
 
+    // TODO: remove this HACK once we settle on optimal default sort coefficients
+    Q_INVOKABLE float getAvatarSortCoefficient(const QString& name);
+    Q_INVOKABLE void setAvatarSortCoefficient(const QString& name, const QScriptValue& value);
+
     float getMyAvatarSendRate() const { return _myAvatarSendRate.rate(); }
 
 public slots:
@@ -120,6 +124,11 @@ private:
     int _partiallySimulatedAvatars { 0 };
     float _avatarSimulationTime { 0.0f };
 
+    // TODO: remove this HACK once we settle on optimal sort coefficients
+    // These coefficients exposed for fine tuning the sort priority for transfering new _jointData to the render pipeline.
+    float _avatarSortCoefficientSize { 0.5f };
+    float _avatarSortCoefficientCenter { 0.25 };
+    float _avatarSortCoefficientAge { 1.0f };
 };
 
 Q_DECLARE_METATYPE(AvatarManager::LocalLight)