From 6fe3c28917e4d2009f9afd92a21fa9d30db77613 Mon Sep 17 00:00:00 2001
From: Kevin Ring <kevin@kotachrome.com>
Date: Mon, 2 Mar 2020 17:04:10 +1100
Subject: [PATCH 1/3] Use LEQUAL instead of LESS for depth testing models.

---
 Source/Scene/Model.js | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Source/Scene/Model.js b/Source/Scene/Model.js
index 9ed90e24741c..60588349425b 100644
--- a/Source/Scene/Model.js
+++ b/Source/Scene/Model.js
@@ -3010,7 +3010,8 @@ import ShadowMode from './ShadowMode.js';
                 enabled : enableCulling
             },
             depthTest : {
-                enabled : true
+                enabled : true,
+                func: WebGLConstants.LEQUAL
             },
             depthMask : !blendingEnabled,
             blending : {

From 248e3f51c5571f8fa8bb06d167fb3fbb3fd4f89d Mon Sep 17 00:00:00 2001
From: Kevin Ring <kevin@kotachrome.com>
Date: Mon, 2 Mar 2020 17:09:12 +1100
Subject: [PATCH 2/3] Update CHANGES.md.

---
 CHANGES.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CHANGES.md b/CHANGES.md
index f6cf17687bd9..ad2c70a63ded 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -5,6 +5,7 @@ Change Log
 
 ##### Breaking Changes :mega:
 * `Cesium3DTileset.skipLevelOfDetail` is now `false` by default. [#8631](https://github.com/CesiumGS/cesium/pull/8631)
+* glTF models are now rendered using the `LEQUALS` depth test function insead of `LESS`. This means that when geometry overlaps, the _later_ geometry will be visible above the earlier, where previously the opposite was true. We believe this is a more sensible default, and makes it easier to render e.g. outlined buildings with glTF.
 
 ##### Additions :tada:
 

From b32e4f3015a81859a989a0a6e15d535d8a5a7a29 Mon Sep 17 00:00:00 2001
From: Kevin Ring <kevin@kotachrome.com>
Date: Mon, 2 Mar 2020 17:25:02 +1100
Subject: [PATCH 3/3] Fix test failure.

---
 Source/Scene/Model.js    | 3 ++-
 Specs/Scene/ModelSpec.js | 4 +++-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/Source/Scene/Model.js b/Source/Scene/Model.js
index 60588349425b..977a32488770 100644
--- a/Source/Scene/Model.js
+++ b/Source/Scene/Model.js
@@ -57,6 +57,7 @@ import Axis from './Axis.js';
 import BlendingState from './BlendingState.js';
 import ClippingPlaneCollection from './ClippingPlaneCollection.js';
 import ColorBlendMode from './ColorBlendMode.js';
+import DepthFunction from './DepthFunction.js';
 import DracoLoader from './DracoLoader.js';
 import getClipAndStyleCode from './getClipAndStyleCode.js';
 import getClippingFunction from './getClippingFunction.js';
@@ -3011,7 +3012,7 @@ import ShadowMode from './ShadowMode.js';
             },
             depthTest : {
                 enabled : true,
-                func: WebGLConstants.LEQUAL
+                func: DepthFunction.LESS_OR_EQUAL
             },
             depthMask : !blendingEnabled,
             blending : {
diff --git a/Specs/Scene/ModelSpec.js b/Specs/Scene/ModelSpec.js
index 574658226ffa..a4e8c92bd67d 100644
--- a/Specs/Scene/ModelSpec.js
+++ b/Specs/Scene/ModelSpec.js
@@ -32,6 +32,7 @@ import { DracoLoader } from '../../Source/Cesium.js';
 import { HeightReference } from '../../Source/Cesium.js';
 import { Model } from '../../Source/Cesium.js';
 import { ModelAnimationLoop } from '../../Source/Cesium.js';
+import { DepthFunction } from '../../Source/Cesium.js';
 import createScene from '../createScene.js';
 import pollToPromise from '../pollToPromise.js';
 import { when } from '../../Source/Cesium.js';
@@ -522,7 +523,8 @@ describe('Scene/Model', function() {
                     enabled : true
                 },
                 depthTest : {
-                    enabled : true
+                    enabled : true,
+                    func : DepthFunction.LESS_OR_EQUAL
                 },
                 depthMask : true,
                 blending : {