Edit docs related to depth buffers

packages/engine/Source/Scene/Camera.js

@@ -2521,10 +2521,8 @@ function rectangleCameraPosition3D(camera, rectangle, result, updateCamera) {
   const ellipsoid = camera._projection.ellipsoid;
   const cameraRF = updateCamera ? camera : defaultRF;
 
-  const north = rectangle.north;
-  const south = rectangle.south;
-  let east = rectangle.east;
-  const west = rectangle.west;
+  const { north, south, west } = rectangle;
+  let { east } = rectangle;
 
   // If we go across the International Date Line
   if (west > east) {

packages/engine/Source/Scene/GlobeDepth.js

@@ -14,6 +14,9 @@ import StencilFunction from "./StencilFunction.js";
 import StencilOperation from "./StencilOperation.js";
 
 /**
+ * @alias GlobeDepth
+ * @constructor
+ *
  * @private
  */
 function GlobeDepth() {

packages/engine/Source/Scene/PickDepth.js

@@ -5,6 +5,9 @@ import FramebufferManager from "../Renderer/FramebufferManager.js";
 import RenderState from "../Renderer/RenderState.js";
 
 /**
+ * @alias PickDepth
+ * @constructor
+ *
  * @private
  */
 function PickDepth() {
@@ -72,6 +75,16 @@ const packedDepthScale = new Cartesian4(
   1.0 / 16581375.0
 );
 
+/**
+ * Read the depth from the framebuffer at the given coordinate.
+ *
+ * @param {Context} context
+ * @param {number} x The x-coordinate at which to read the depth.
+ * @param {number} y The y-coordinate at which to read the depth.
+ * @returns {number} The depth read from the framebuffer.
+ *
+ * @private
+ */
 PickDepth.prototype.getDepth = function (context, x, y) {
   // If this function is called before the framebuffer is created, the depth is undefined.
   if (!defined(this.framebuffer)) {

packages/engine/Source/Scene/Picking.js

@@ -495,7 +495,7 @@ Picking.prototype.pickPositionWorldCoordinates = function (
     frustum = camera.frustum.clone(scratchOrthographicOffCenterFrustum);
   }
 
-  const frustumCommandsList = defaultView.frustumCommandsList;
+  const { frustumCommandsList } = defaultView;
   const numFrustums = frustumCommandsList.length;
   for (let i = 0; i < numFrustums; ++i) {
     const pickDepth = this.getPickDepth(scene, i);
@@ -855,15 +855,16 @@ function getRayIntersection(
   const object = view.pickFramebuffer.end(scratchRectangle);
 
   if (scene.context.depthTexture) {
-    const numFrustums = view.frustumCommandsList.length;
+    const { frustumCommandsList } = view;
+    const numFrustums = frustumCommandsList.length;
     for (let i = 0; i < numFrustums; ++i) {
       const pickDepth = picking.getPickDepth(scene, i);
       const depth = pickDepth.getDepth(context, 0, 0);
       if (!defined(depth)) {
         continue;
       }
       if (depth > 0.0 && depth < 1.0) {
-        const renderedFrustum = view.frustumCommandsList[i];
+        const renderedFrustum = frustumCommandsList[i];
         const near =
           renderedFrustum.near *
           (i !== 0 ? scene.opaqueFrustumNearOffset : 1.0);

packages/engine/Source/Scene/Scene.js

@@ -2484,8 +2484,6 @@ function executeCommands(scene, passState) {
     // Draw terrain classification
     if (!environmentState.renderTranslucentDepthForPick) {
       uniformState.updatePass(Pass.TERRAIN_CLASSIFICATION);
-      const commands = frustumCommands.commands[Pass.TERRAIN_CLASSIFICATION];
-      length = frustumCommands.indices[Pass.TERRAIN_CLASSIFICATION];
 
       if (globeTranslucent) {
         globeTranslucencyState.executeGlobeClassificationCommands(
@@ -2496,6 +2494,8 @@ function executeCommands(scene, passState) {
           passState
         );
       } else {
+        const commands = frustumCommands.commands[Pass.TERRAIN_CLASSIFICATION];
+        length = frustumCommands.indices[Pass.TERRAIN_CLASSIFICATION];
         for (let j = 0; j < length; ++j) {
           executeCommand(commands[j], scene, context, passState);
         }
@@ -3169,10 +3169,8 @@ function executeCommandsInViewport(
   passState,
   backgroundColor
 ) {
-  const environmentState = scene._environmentState;
   const view = scene._view;
-  const renderTranslucentDepthForPick =
-    environmentState.renderTranslucentDepthForPick;
+  const { renderTranslucentDepthForPick } = scene._environmentState;
 
   if (!firstViewport) {
     scene.frameState.commandList.length = 0;
@@ -3355,21 +3353,21 @@ function updateDebugFrustumPlanes(scene) {
 
 function updateShadowMaps(scene) {
   const frameState = scene._frameState;
-  const shadowMaps = frameState.shadowMaps;
+  const { passes, shadowState, shadowMaps } = frameState;
   const length = shadowMaps.length;
 
   const shadowsEnabled =
     length > 0 &&
-    !frameState.passes.pick &&
-    !frameState.passes.pickVoxel &&
+    !passes.pick &&
+    !passes.pickVoxel &&
     scene.mode === SceneMode.SCENE3D;
-  if (shadowsEnabled !== frameState.shadowState.shadowsEnabled) {
+  if (shadowsEnabled !== shadowState.shadowsEnabled) {
     // Update derived commands when shadowsEnabled changes
-    ++frameState.shadowState.lastDirtyTime;
-    frameState.shadowState.shadowsEnabled = shadowsEnabled;
+    ++shadowState.lastDirtyTime;
+    shadowState.shadowsEnabled = shadowsEnabled;
   }
 
-  frameState.shadowState.lightShadowsEnabled = false;
+  shadowState.lightShadowsEnabled = false;
 
   if (!shadowsEnabled) {
     return;
@@ -3378,28 +3376,28 @@ function updateShadowMaps(scene) {
   // Check if the shadow maps are different than the shadow maps last frame.
   // If so, the derived commands need to be updated.
   for (let j = 0; j < length; ++j) {
-    if (shadowMaps[j] !== frameState.shadowState.shadowMaps[j]) {
-      ++frameState.shadowState.lastDirtyTime;
+    if (shadowMaps[j] !== shadowState.shadowMaps[j]) {
+      ++shadowState.lastDirtyTime;
       break;
     }
   }
 
-  frameState.shadowState.shadowMaps.length = 0;
-  frameState.shadowState.lightShadowMaps.length = 0;
+  shadowState.shadowMaps.length = 0;
+  shadowState.lightShadowMaps.length = 0;
 
   for (let i = 0; i < length; ++i) {
     const shadowMap = shadowMaps[i];
     shadowMap.update(frameState);
 
-    frameState.shadowState.shadowMaps.push(shadowMap);
+    shadowState.shadowMaps.push(shadowMap);
 
     if (shadowMap.fromLightSource) {
-      frameState.shadowState.lightShadowMaps.push(shadowMap);
-      frameState.shadowState.lightShadowsEnabled = true;
+      shadowState.lightShadowMaps.push(shadowMap);
+      shadowState.lightShadowsEnabled = true;
     }
 
     if (shadowMap.dirty) {
-      ++frameState.shadowState.lastDirtyTime;
+      ++shadowState.lastDirtyTime;
       shadowMap.dirty = false;
     }
   }

packages/engine/Source/Scene/View.js

@@ -28,6 +28,13 @@ function CommandExtent() {
 }
 
 /**
+ * @alias View
+ * @constructor
+ *
+ * @param {Scene} scene
+ * @param {Camera} camera
+ * @param {BoundingRectangle} viewport
+ *
  * @private
  */
 function View(scene, camera, viewport) {
@@ -62,6 +69,9 @@ function View(scene, camera, viewport) {
   this.translucentTileClassification = new TranslucentTileClassification(
     context
   );
+  /**
+   * @type {PickDepth[]}
+   */
   this.pickDepths = [];
   this.frustumCommandsList = [];
   this.debugFrustumStatistics = undefined;

packages/engine/Source/Shaders/Builtin/Functions/packDepth.glsl

@@ -1,11 +1,11 @@
 /**
- * Packs a depth value into a vec3 that can be represented by unsigned bytes.
+ * Packs a depth value into a vec4 that can be represented by unsigned bytes.
  *
  * @name czm_packDepth
  * @glslFunction
  *
  * @param {float} depth The floating-point depth.
- * @returns {vec3} The packed depth.
+ * @returns {vec4} The packed depth.
  */
 vec4 czm_packDepth(float depth)
 {