From 0d33965c38910fdd3db09d3975ae1da5f52801e5 Mon Sep 17 00:00:00 2001
From: Sean Lilley <lilleyse@gmail.com>
Date: Fri, 20 Sep 2019 15:23:48 -0400
Subject: [PATCH] Lower depth plane below marianna trench

---
 Source/Scene/DepthPlane.js | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/Source/Scene/DepthPlane.js b/Source/Scene/DepthPlane.js
index ebb85625175..c66d7af8b65 100644
--- a/Source/Scene/DepthPlane.js
+++ b/Source/Scene/DepthPlane.js
@@ -1,4 +1,5 @@
 define([
+        '../Core/ApproximateTerrainHeights',
         '../Core/BoundingSphere',
         '../Core/Cartesian3',
         '../Core/ComponentDatatype',
@@ -18,6 +19,7 @@ define([
         '../Shaders/DepthPlaneVS',
         './SceneMode'
     ], function(
+        ApproximateTerrainHeights,
         BoundingSphere,
         Cartesian3,
         ComponentDatatype,
@@ -51,15 +53,23 @@ define([
     }
 
     var depthQuadScratch = FeatureDetection.supportsTypedArrays() ? new Float32Array(12) : [];
+    var scratchRadii = new Cartesian3();
     var scratchCartesian1 = new Cartesian3();
     var scratchCartesian2 = new Cartesian3();
     var scratchCartesian3 = new Cartesian3();
     var scratchCartesian4 = new Cartesian3();
 
     function computeDepthQuad(ellipsoid, frameState) {
-        var radii = ellipsoid.radii;
+        var radii = Cartesian3.clone(ellipsoid.radii, scratchRadii);
         var p = frameState.camera.positionWC;
 
+        // This effectively pushes the depth plane farther from the camera so that the depth plane does not render
+        // above primitives in the scene.
+        var radiusOffset = -ApproximateTerrainHeights._defaultMinTerrainHeight;
+        radii.x -= radiusOffset;
+        radii.y -= radiusOffset;
+        radii.z -= radiusOffset;
+
         // Find the corresponding position in the scaled space of the ellipsoid.
         var q = Cartesian3.multiplyComponents(ellipsoid.oneOverRadii, p, scratchCartesian1);