Updates from review

Source/Renderer/AutomaticUniforms.js

@@ -1043,9 +1043,28 @@ var AutomaticUniforms = {
     },
   }),
 
+  /**
+   * An automatic GLSL uniform containing the height in meters of the
+   * eye (camera) above or below the ellipsoid.
+   *
+   * @alias czm_eyeHeight
+   * @namespace
+   * @glslUniform
+   *
+   * @see UniformState#eyeHeight
+   */
+  czm_eyeHeight: new AutomaticUniform({
+    size: 1,
+    datatype: WebGLConstants.FLOAT,
+    getValue: function (uniformState) {
+      return uniformState.eyeHeight;
+    },
+  }),
+
   /**
    * An automatic GLSL uniform containing height (<code>x</code>) and height squared (<code>y</code>)
-   *  of the eye (camera) in the 2D scene in meters.
+   * in meters of the eye (camera) above the 2D world plane. This uniform is only valid
+   * when the {@link SceneMode} is <code>SCENE2D</code>.
    *
    * @alias czm_eyeHeight2D
    * @namespace
@@ -1896,19 +1915,5 @@ var AutomaticUniforms = {
       return uniformState.ellipsoid.oneOverRadii;
     },
   }),
-
-  /**
-   * An automatic GLSL uniform that stores the camera's height above or below the ellipsoid.
-   *
-   * @alias czm_cameraHeight
-   * @glslUniform
-   */
-  czm_cameraHeight: new AutomaticUniform({
-    size: 1,
-    datatype: WebGLConstants.FLOAT,
-    getValue: function (uniformState) {
-      return uniformState.cameraHeight;
-    },
-  }),
 };
 export default AutomaticUniforms;

Source/Renderer/UniformState.js

@@ -141,8 +141,8 @@ function UniformState() {
   this._cameraDirection = new Cartesian3();
   this._cameraRight = new Cartesian3();
   this._cameraUp = new Cartesian3();
-  this._cameraHeight = 0.0;
   this._frustum2DWidth = 0.0;
+  this._eyeHeight = 0.0;
   this._eyeHeight2D = new Cartesian2();
   this._pixelRatio = 1.0;
   this._orthographicIn3D = false;
@@ -673,9 +673,20 @@ Object.defineProperties(UniformState.prototype, {
   },
 
   /**
-   * The the height (<code>x</code>) and the height squared (<code>y</code>)
-   * in meters of the camera above the 2D world plane. This uniform is only valid
-   * when the {@link SceneMode} equal to <code>SCENE2D</code>.
+   * The height in meters of the eye (camera) above or below the ellipsoid.
+   * @memberof UniformState.prototype
+   * @type {Number}
+   */
+  eyeHeight: {
+    get: function () {
+      return this._eyeHeight;
+    },
+  },
+
+  /**
+   * The height (<code>x</code>) and the height squared (<code>y</code>)
+   * in meters of the eye (camera) above the 2D world plane. This uniform is only valid
+   * when the {@link SceneMode} is <code>SCENE2D</code>.
    * @memberof UniformState.prototype
    * @type {Cartesian2}
    */
@@ -1011,18 +1022,6 @@ Object.defineProperties(UniformState.prototype, {
       return defaultValue(this._ellipsoid, Ellipsoid.WGS84);
     },
   },
-
-  /**
-   * The camera's height above or below the ellipsoid.
-   *
-   * @memberof UniformState.prototype
-   * @type {Number}
-   */
-  cameraHeight: {
-    get: function () {
-      return this._cameraHeight;
-    },
-  },
 });
 
 function setView(uniformState, matrix) {
@@ -1076,9 +1075,9 @@ function setCamera(uniformState, camera) {
 
   var positionCartographic = camera.positionCartographic;
   if (!defined(positionCartographic)) {
-    uniformState._cameraHeight = -uniformState._ellipsoid.maximumRadius;
+    uniformState._eyeHeight = -uniformState._ellipsoid.maximumRadius;
   } else {
-    uniformState._cameraHeight = positionCartographic.height;
+    uniformState._eyeHeight = positionCartographic.height;
   }
 
   uniformState._encodedCameraPositionMCDirty = true;

Source/Scene/processModelMaterialsCommon.js

@@ -642,7 +642,6 @@ function generateTechnique(
   if (hasNormals) {
     fragmentShader += "  vec3 normal = normalize(v_normal);\n";
     if (khrMaterialsCommon.doubleSided) {
-      // !gl_FrontFacing doesn't work as expected on Mac/Intel so use the more verbose form instead. See https://github.com/CesiumGS/cesium/pull/8494.
       fragmentShader += "  if (czm_backFacing())\n";
       fragmentShader += "  {\n";
       fragmentShader += "    normal = -normal;\n";

Source/Scene/processPbrMaterials.js

@@ -767,7 +767,6 @@ function generateTechnique(
       fragmentShader += "    vec3 n = ng;\n";
     }
     if (material.doubleSided) {
-      // !gl_FrontFacing doesn't work as expected on Mac/Intel so use the more verbose form instead. See https://github.com/CesiumGS/cesium/pull/8494.
       fragmentShader += "    if (czm_backFacing())\n";
       fragmentShader += "    {\n";
       fragmentShader += "        n = -n;\n";

Source/Shaders/GlobeFS.glsl

@@ -423,7 +423,7 @@ void main()
 #ifdef UNDERGROUND_COLOR
     if (czm_backFacing())
     {
-        float distanceFromEllipsoid = max(czm_cameraHeight, 0.0);
+        float distanceFromEllipsoid = max(czm_eyeHeight, 0.0);
         float distance = max(v_distance - distanceFromEllipsoid, 0.0);
         float blendAmount = interpolateByDistance(u_undergroundColorAlphaByDistance, distance);
         vec4 undergroundColor = vec4(u_undergroundColor.rgb, u_undergroundColor.a * blendAmount);

Specs/Renderer/AutomaticUniformSpec.js

@@ -1947,6 +1947,20 @@ describe(
       }).contextToRender();
     });
 
+    it("has czm_eyeHeight", function () {
+      var frameState = createFrameState(context, createMockCamera());
+      context.uniformState.update(frameState);
+
+      var fs =
+        "void main() { " +
+        "  gl_FragColor = vec4(czm_eyeHeight == 10.0); " +
+        "}";
+      expect({
+        context: context,
+        fragmentShader: fs,
+      }).contextToRender();
+    });
+
     it("has czm_eyeHeight2D == 0,0 in Scene3D", function () {
       var fs =
         "void main() { " +
@@ -2171,20 +2185,6 @@ describe(
         fragmentShader: fs,
       }).contextToRender();
     });
-
-    it("has czm_cameraHeight", function () {
-      var frameState = createFrameState(context, createMockCamera());
-      context.uniformState.update(frameState);
-
-      var fs =
-        "void main() { " +
-        "  gl_FragColor = vec4(czm_cameraHeight == 10.0); " +
-        "}";
-      expect({
-        context: context,
-        fragmentShader: fs,
-      }).contextToRender();
-    });
   },
   "WebGL"
 );