Move horizon distance calculation from WWMath to Globe.

Author: EMaksymenko

src/WorldWindow.js

@@ -217,6 +217,12 @@ define([
              */
             this.verticalExaggeration = 1;
 
+            /**
+             * Distance from camera point to horizon.
+             * @type {Number}
+             */
+            this.horizonDistance = 0;
+
             /**
              * Indicates that picking will return all objects at the pick point, if any. The top-most object will have
              * its isOnTop flag set to true.
@@ -707,11 +713,10 @@ define([
             this.camera.computeViewingTransform(modelview);
 
             if (projection) {
-                var globeRadius = WWMath.max(this.globe.equatorialRadius, this.globe.polarRadius),
-                    eyePos = this.camera.position,
+                var eyePos = this.camera.position,
                     fieldOfView = this.camera.fieldOfView,
-                    eyeHorizon = WWMath.horizonDistanceForGlobeRadius(globeRadius, eyePos.altitude),
-                    atmosphereHorizon = WWMath.horizonDistanceForGlobeRadius(globeRadius, 160000),
+                    eyeHorizon = this.globe.horizonDistance(eyePos.altitude),
+                    atmosphereHorizon = this.globe.horizonDistance(160000),
                     viewport = this.viewport;
 
                 // Set the far clip distance to the smallest value that does not clip the atmosphere.
@@ -805,6 +810,7 @@ define([
             dc.globe = this.globe;
             dc.navigator = this.navigator;
             dc.camera = this.camera;
+            dc.horizonDistance = this.globe.horizonDistance(this.camera.position.altitude);
             dc.layers = this.layers.slice();
             dc.layers.push(dc.screenCreditController);
             this.computeDrawContext();

src/geom/Camera.js

@@ -278,8 +278,7 @@ define([
                 modelview.extractEyePoint(forwardRay.origin);
                 modelview.extractForwardVector(forwardRay.direction);
 
-                var globeRadius = WWMath.max(globe.equatorialRadius, globe.polarRadius);
-                var horizon = WWMath.horizonDistanceForGlobeRadius(globeRadius, this.position.altitude);
+                var horizon = globe.horizonDistance(this.position.altitude);
                 forwardRay.pointAt(horizon, originPoint);
 
                 globe.computePositionFromPoint(originPoint[0], originPoint[1], originPoint[2], originPos);

src/globe/Globe.js

@@ -677,5 +677,18 @@ define([
             return this.elevationModel.elevationsForGrid(sector, numLat, numLon, targetResolution, result);
         };
 
+        /**
+         * Computes the distance to a globe's horizon from a viewer at a given altitude.
+         *
+         * Only the globe's ellipsoid is considered; terrain height is not incorporated.
+         * This returns zero if the altitude is less than or equal to zero.
+         *
+         * @param {Number} altitude The viewer's altitude above the globe, in meters.
+         * @returns {Number} The distance to the horizon, in model coordinates.
+         */
+        Globe.prototype.horizonDistance = function (altitude) {
+            return (altitude > 0) ? Math.sqrt(altitude * (2 * this.equatorialRadius + altitude)) : 0;
+        };
+
         return Globe;
     });

src/util/WWMath.js

@@ -600,26 +600,6 @@ define([
                 yAxisResult.normalize();
             },
 
-            /**
-             * Computes the distance to a globe's horizon from a viewer at a given altitude.
-             *
-             * Only the globe's ellipsoid is considered; terrain height is not incorporated. This returns zero if the radius is zero
-             * or if the altitude is less than or equal to zero.
-             *
-             * @param {Number} radius The globe's radius, in meters.
-             * @param {Number} altitude The viewer's altitude above the globe, in meters.
-             * @returns {Number} The distance to the horizon, in model coordinates.
-             * @throws {ArgumentError} If the specified globe radius is negative.
-             */
-            horizonDistanceForGlobeRadius: function (radius, altitude) {
-                if (radius < 0) {
-                    throw new ArgumentError(Logger.logMessage(Logger.LEVEL_SEVERE, "WWMath",
-                        "horizontalDistanceForGlobeRadius", "The specified globe radius is negative."));
-                }
-
-                return (radius > 0 && altitude > 0) ? Math.sqrt(altitude * (2 * radius + altitude)) : 0;
-            },
-
             /**
              * Computes the near clip distance that corresponds to a specified far clip distance and resolution at the far clip
              * plane.