From 3686c4c093d4a16beb158149af3c3e5aed559222 Mon Sep 17 00:00:00 2001
From: David Collins <paul@paulcollinssoftware.com>
Date: Sat, 5 Aug 2017 10:21:37 -0700
Subject: [PATCH] Repaired atmosphere layer clipping - Adjusted Web WorldWind's
 far clip distance computation to match that of WorldWind Android. - The
 resultant distance correctly captures the distance between the globe's
 horizon and the atmosphere's horizon. - Brought the Atmosphere example's
 canvas size into convention with the other examples.

---
 examples/Atmosphere.html  |  2 +-
 src/navigate/Navigator.js | 11 +++++++----
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/examples/Atmosphere.html b/examples/Atmosphere.html
index f087198c..4b3de40f 100644
--- a/examples/Atmosphere.html
+++ b/examples/Atmosphere.html
@@ -42,7 +42,7 @@
             </div>
         </div>
         <div class="col-sm-9" id="globe">
-            <canvas id="canvasOne" width="1000" height="1000" style="background-color: #000000">
+            <canvas id="canvasOne" width="1000" height="1000" style="width: 100%; height: auto; background-color: black;">
                 Your browser does not support HTML5 Canvas.
             </canvas>
         </div>
diff --git a/src/navigate/Navigator.js b/src/navigate/Navigator.js
index bb4e4831..013c7971 100644
--- a/src/navigate/Navigator.js
+++ b/src/navigate/Navigator.js
@@ -102,16 +102,19 @@ define([
                 globeRadius = WWMath.max(globe.equatorialRadius, globe.polarRadius),
                 eyePoint = modelviewMatrix.extractEyePoint(new Vec3(0, 0, 0)),
                 eyePos = globe.computePositionFromPoint(eyePoint[0], eyePoint[1], eyePoint[2], new Position(0, 0, 0)),
+                eyeHorizon = WWMath.horizonDistanceForGlobeRadius(globeRadius, eyePos.altitude),
+                atmosphereHorizon = WWMath.horizonDistanceForGlobeRadius(globeRadius, 160000),
                 viewport = this.worldWindow.viewport,
                 viewDepthBits = this.worldWindow.depthBits,
                 distanceToSurface,
                 maxNearDistance,
                 projectionMatrix = Matrix.fromIdentity();
 
-            // Compute the far clip distance based on the current eye altitude. This must be done after computing the
-            // modelview matrix and before computing the near clip distance. The far clip distance depends on the
-            // modelview matrix, and the near clip distance depends on the far clip distance.
-            this.farDistance = WWMath.horizonDistanceForGlobeRadius(globeRadius, eyePos.altitude);
+            // Set the far clip distance to the smallest value that does not clip the atmosphere.
+            // TODO adjust the clip plane distances based on the navigator's orientation - shorter distances when the
+            // TODO horizon is not in view
+            // TODO parameterize the object altitude for horizon distance
+            this.farDistance = eyeHorizon + atmosphereHorizon;
             if (this.farDistance < 1e3)
                 this.farDistance = 1e3;