Make the LOD half angle the definitive LOD variable

interface/src/LODManager.cpp

@@ -12,7 +12,6 @@
 #include "LODManager.h"
 
 #include <SettingHandle.h>
-#include <OctreeUtils.h>
 #include <Util.h>
 #include <shared/GlobalAppProperties.h>
 
@@ -165,7 +164,7 @@ void LODManager::autoAdjustLOD(float realTimeDelta) {
     // And now add the output of the controller to the LODAngle where we will guarantee it is in the proper range
     setLODAngleDeg(oldLODAngle + output);
 
-    if (oldVisibilityDistance != _visibilityDistance) {
+    if (oldLODAngle != getLODAngleDeg()) {
         auto lodToolsDialog = DependencyManager::get<DialogsManager>()->getLodToolsDialog();
         if (lodToolsDialog) {
             lodToolsDialog->reloadSliders();
@@ -174,22 +173,26 @@ void LODManager::autoAdjustLOD(float realTimeDelta) {
 }
 
 float LODManager::getLODHalfAngleTan() const {
-    return getPerspectiveAccuracyHalfAngleTan(_visibilityDistance, _boundaryLevelAdjust);
+    return tan(_lodHalfAngle);
 
 }
 float LODManager::getLODAngle() const {
-    return 2.0f * atanf(getLODHalfAngleTan());
+    return 2.0f * _lodHalfAngle;
 }
 float LODManager::getLODAngleDeg() const {
     return glm::degrees(getLODAngle());
 }
 
 float LODManager::getVisibilityDistance() const {
-    return _visibilityDistance;
+    float systemDistance = getVisibilityDistanceFromHalfAngle(_lodHalfAngle);
+    // Maintain behavior with deprecated _boundaryLevelAdjust property
+    return systemDistance * powf(2.0f, _boundaryLevelAdjust);
 }
 
 void LODManager::setVisibilityDistance(float distance) {
-    _visibilityDistance = distance;
+    // Maintain behavior with deprecated _boundaryLevelAdjust property
+    float userDistance = distance / powf(2.0f, _boundaryLevelAdjust);
+    _lodHalfAngle = getHalfAngleFromVisibilityDistance(userDistance);
 }
 
 void LODManager::setLODAngleDeg(float lodAngle) {

interface/src/LODManager.h

@@ -17,6 +17,7 @@
 #include <DependencyManager.h>
 #include <NumericalConstants.h>
 #include <OctreeConstants.h>
+#include <OctreeUtils.h>
 #include <PIDController.h>
 #include <SimpleMovingAverage.h>
 #include <render/Args.h>
@@ -261,7 +262,7 @@ private:
     float _desktopTargetFPS { LOD_OFFSET_FPS + LOD_DEFAULT_QUALITY_LEVEL * LOD_MAX_LIKELY_DESKTOP_FPS };
     float _hmdTargetFPS { LOD_OFFSET_FPS + LOD_DEFAULT_QUALITY_LEVEL * LOD_MAX_LIKELY_HMD_FPS };
 
-    float _visibilityDistance = DEFAULT_VISIBILITY_DISTANCE_FOR_UNIT_ELEMENT;
+    float _lodHalfAngle = getHalfAngleFromVisibilityDistance(DEFAULT_VISIBILITY_DISTANCE_FOR_UNIT_ELEMENT);
     int _boundaryLevelAdjust = 0;
 
     glm::vec4 _pidCoefs{ 1.0f, 0.0f, 0.0f, 1.0f }; // Kp, Ki, Kd, Kv

libraries/octree/src/OctreeUtils.cpp

@@ -31,6 +31,15 @@ float getPerspectiveAccuracyHalfAngle(float visibilityDistance, int boundaryLeve
     return atan(getPerspectiveAccuracyHalfAngleTan(visibilityDistance, boundaryLevelAdjust));
 }
 
+float getVisibilityDistanceFromHalfAngle(float halfAngle) {
+    float halfAngleTan = tan(halfAngle);
+    return UNIT_ELEMENT_MAX_EXTENT / halfAngleTan;
+}
+
+float getHalfAngleFromVisibilityDistance(float visibilityDistance) {
+    return UNIT_ELEMENT_MAX_EXTENT / visibilityDistance;
+}
+
 float getOrthographicAccuracySize(float visibilityDistance, int boundaryLevelAdjust) {
     // Smallest visible element is 1cm
     const float smallestSize = 0.01f;

libraries/octree/src/OctreeUtils.h

@@ -24,6 +24,8 @@ float boundaryDistanceForRenderLevel(unsigned int renderLevel, float visibilityD
 
 float getPerspectiveAccuracyHalfAngleTan(float visibilityDistance, int boundaryLevelAdjust);
 float getPerspectiveAccuracyHalfAngle(float visibilityDistance, int boundaryLevelAdjust);
+float getVisibilityDistanceFromHalfAngle(float halfAngle);
+float getHalfAngleFromVisibilityDistance(float visibilityDistance);
 float getOrthographicAccuracySize(float visibilityDistance, int boundaryLevelAdjust);
 
 // MIN_ELEMENT_ANGULAR_DIAMETER = angular diameter of 1x1x1m cube at 400m = sqrt(3) / 400 = 0.0043301 radians ~= 0.25 degrees