Fix classification when terrain depth writes are enabled

Apps/Sandcastle/gallery/Classification Types.html

@@ -30,7 +30,6 @@
 var viewer = new Cesium.Viewer('cesiumContainer', {
     terrainProvider: Cesium.createWorldTerrain()
 });
-viewer.scene.globe.depthTestAgainstTerrain = false;
 
 var tileset = new Cesium.Cesium3DTileset({ url: Cesium.IonResource.fromAssetId(6074) });
 viewer.scene.primitives.add(tileset);

CHANGES.md

@@ -1,6 +1,12 @@
 Change Log
 ==========
 
+### 1.45 - 2019-02-01
+
+##### Fixes :wrench:
+* Fixed an issue where classification primitives with the `CESIUM_3D_TILE` classification type would render on terrain. [#6568](https://github.com/AnalyticalGraphicsInc/cesium/issues/6568)
+* Fixed an issue where 3D Tiles would show through the globe. [#6867](https://github.com/AnalyticalGraphicsInc/cesium/issues/6867)
+
 ### 1.53 - 2019-01-02
 
 ##### Fixes :wrench:

Source/Renderer/Pass.js

@@ -24,11 +24,10 @@ define([
         CESIUM_3D_TILE : 4,
         CESIUM_3D_TILE_CLASSIFICATION : 5,
         CESIUM_3D_TILE_CLASSIFICATION_IGNORE_SHOW : 6,
-        CLASSIFICATION : 7,
-        OPAQUE : 8,
-        TRANSLUCENT : 9,
-        OVERLAY : 10,
-        NUMBER_OF_PASSES : 11
+        OPAQUE : 7,
+        TRANSLUCENT : 8,
+        OVERLAY : 9,
+        NUMBER_OF_PASSES : 10
     };
 
     return freezeObject(Pass);

Source/Scene/Cesium3DTileBatchTable.js

@@ -31,6 +31,7 @@ define([
         './Cesium3DTileColorBlendMode',
         './CullFace',
         './getBinaryAccessor',
+        './StencilConstants',
         './StencilFunction',
         './StencilOperation'
     ], function(
@@ -66,6 +67,7 @@ define([
         Cesium3DTileColorBlendMode,
         CullFace,
         getBinaryAccessor,
+        StencilConstants,
         StencilFunction,
         StencilOperation) {
     'use strict';
@@ -1261,30 +1263,42 @@ define([
                 derivedCommands.originalCommand = deriveCommand(command);
                 command.dirty = false;
             }
+            var originalCommand = derivedCommands.originalCommand;
 
-            if (styleCommandsNeeded !== StyleCommandsNeeded.ALL_OPAQUE) {
+            if (styleCommandsNeeded !== StyleCommandsNeeded.ALL_OPAQUE && command.pass !== Pass.TRANSLUCENT) {
                 if (!defined(derivedCommands.translucent)) {
-                    derivedCommands.translucent = deriveTranslucentCommand(derivedCommands.originalCommand);
+                    derivedCommands.translucent = deriveTranslucentCommand(originalCommand);
                 }
             }
 
-            if (bivariateVisibilityTest) {
-                if (command.pass !== Pass.TRANSLUCENT && !finalResolution) {
-                    if (!defined(derivedCommands.zback)) {
-                        derivedCommands.zback = deriveZBackfaceCommand(frameState.context, derivedCommands.originalCommand);
-                    }
-                    tileset._backfaceCommands.push(derivedCommands.zback);
+            if (styleCommandsNeeded !== StyleCommandsNeeded.ALL_TRANSLUCENT && command.pass !== Pass.TRANSLUCENT) {
+                if (!defined(derivedCommands.opaque)) {
+                    derivedCommands.opaque = deriveOpaqueCommand(originalCommand);
                 }
-                if (!defined(derivedCommands.stencil) || tile._selectionDepth !== getLastSelectionDepth(derivedCommands.stencil)) {
-                    derivedCommands.stencil = deriveStencilCommand(derivedCommands.originalCommand, tile._selectionDepth);
+
+                if (bivariateVisibilityTest) {
+                    if (!finalResolution) {
+                        if (!defined(derivedCommands.zback)) {
+                            derivedCommands.zback = deriveZBackfaceCommand(frameState.context, originalCommand);
+                        }
+                        tileset._backfaceCommands.push(derivedCommands.zback);
+                    }
+                    if (!defined(derivedCommands.stencil) || (tile._selectionDepth !== getLastSelectionDepth(derivedCommands.stencil))) {
+                        if (command.renderState.depthMask) {
+                            derivedCommands.stencil = deriveStencilCommand(originalCommand, tile._selectionDepth);
+                        } else {
+                            // Ignore if tile does not write depth
+                            derivedCommands.stencil = derivedCommands.opaque;
+                        }
+                    }
                 }
             }
 
-            var opaqueCommand = bivariateVisibilityTest ? derivedCommands.stencil : derivedCommands.originalCommand;
+            var opaqueCommand = bivariateVisibilityTest ? derivedCommands.stencil : derivedCommands.opaque;
             var translucentCommand = derivedCommands.translucent;
 
             // If the command was originally opaque:
-            //    * If the styling applied to the tile is all opaque, use the original command
+            //    * If the styling applied to the tile is all opaque, use the opaque command
             //      (with one additional uniform needed for the shader).
             //    * If the styling is all translucent, use new (cached) derived commands (front
             //      and back faces) with a translucent render state.
@@ -1308,7 +1322,7 @@ define([
                 // as of now, a style can't change an originally translucent feature to
                 // opaque since the style's alpha is modulated, not a replacement.  When
                 // this changes, we need to derive new opaque commands here.
-                commandList[i] = opaqueCommand;
+                commandList[i] = originalCommand;
             }
         }
     };
@@ -1348,6 +1362,12 @@ define([
         return derivedCommand;
     }
 
+    function deriveOpaqueCommand(command) {
+        var derivedCommand = DrawCommand.shallowClone(command);
+        derivedCommand.renderState = getOpaqueRenderState(command.renderState);
+        return derivedCommand;
+    }
+
     function getDisableLogDepthFragmentShaderProgram(context, shaderProgram) {
         var shader = context.shaderCache.getDerivedShaderProgram(shaderProgram, 'zBackfaceLogDepth');
         if (!defined(shader)) {
@@ -1385,6 +1405,10 @@ define([
             factor : 5.0,
             units : 5.0
         };
+        // Set the 3D Tiles bit
+        rs.stencilTest = StencilConstants.setCesium3DTileBit();
+        rs.stencilMask = StencilConstants.CESIUM_3D_TILE_MASK;
+
         derivedCommand.renderState = RenderState.fromCache(rs);
         derivedCommand.castShadows = false;
         derivedCommand.receiveShadows = false;
@@ -1395,27 +1419,27 @@ define([
     }
 
     function deriveStencilCommand(command, reference) {
-        var derivedCommand = command;
-        if (command.renderState.depthMask) { // ignore if tile does not write depth (ex. translucent)
-            // Tiles only draw if their selection depth is >= the tile drawn already. They write their
-            // selection depth to the stencil buffer to prevent ancestor tiles from drawing on top
-            derivedCommand = DrawCommand.shallowClone(command);
-            var rs = clone(derivedCommand.renderState, true);
-            // Stencil test is masked to the most significant 4 bits so the reference is shifted.
-            // This is to prevent clearing the stencil before classification which needs the least significant
-            // bits for increment/decrement operations.
-            rs.stencilTest.enabled = true;
-            rs.stencilTest.mask = 0xF0;
-            rs.stencilTest.reference = reference << 4;
-            rs.stencilTest.frontFunction = StencilFunction.GREATER_OR_EQUAL;
-            rs.stencilTest.frontOperation.zPass = StencilOperation.REPLACE;
-            derivedCommand.renderState = RenderState.fromCache(rs);
-        }
+        // Tiles only draw if their selection depth is >= the tile drawn already. They write their
+        // selection depth to the stencil buffer to prevent ancestor tiles from drawing on top
+        var derivedCommand = DrawCommand.shallowClone(command);
+        var rs = clone(derivedCommand.renderState, true);
+        // Stencil test is masked to the most significant 3 bits so the reference is shifted. Writes 0 for the terrain bit
+        rs.stencilTest.enabled = true;
+        rs.stencilTest.mask = StencilConstants.SKIP_LOD_MASK;
+        rs.stencilTest.reference = StencilConstants.CESIUM_3D_TILE_MASK | (reference << StencilConstants.SKIP_LOD_BIT_SHIFT);
+        rs.stencilTest.frontFunction = StencilFunction.GREATER_OR_EQUAL;
+        rs.stencilTest.frontOperation.zPass = StencilOperation.REPLACE;
+        rs.stencilTest.backFunction = StencilFunction.GREATER_OR_EQUAL;
+        rs.stencilTest.backOperation.zPass = StencilOperation.REPLACE;
+        rs.stencilMask = StencilConstants.CESIUM_3D_TILE_MASK | StencilConstants.SKIP_LOD_MASK;
+        derivedCommand.renderState = RenderState.fromCache(rs);
         return derivedCommand;
     }
 
     function getLastSelectionDepth(stencilCommand) {
-        return stencilCommand.renderState.stencilTest.reference >>> 4;
+        // Isolate the selection depth from the stencil reference.
+        var reference = stencilCommand.renderState.stencilTest.reference;
+        return (reference & StencilConstants.SKIP_LOD_MASK) >>> StencilConstants.SKIP_LOD_BIT_SHIFT;
     }
 
     function getTranslucentRenderState(renderState) {
@@ -1428,6 +1452,14 @@ define([
         return RenderState.fromCache(rs);
     }
 
+    function getOpaqueRenderState(renderState) {
+        var rs = clone(renderState, true);
+        rs.stencilTest = StencilConstants.setCesium3DTileBit();
+        rs.stencilMask = StencilConstants.CESIUM_3D_TILE_MASK;
+
+        return RenderState.fromCache(rs);
+    }
+
     ///////////////////////////////////////////////////////////////////////////
 
     function createTexture(batchTable, context, bytes) {

Source/Scene/Cesium3DTileset.js

@@ -22,6 +22,7 @@ define([
         '../Core/Transforms',
         '../Renderer/ClearCommand',
         '../Renderer/Pass',
+        '../Renderer/RenderState',
         '../ThirdParty/when',
         './Axis',
         './Cesium3DTile',
@@ -40,6 +41,7 @@ define([
         './PointCloudShading',
         './SceneMode',
         './ShadowMode',
+        './StencilConstants',
         './TileBoundingRegion',
         './TileBoundingSphere',
         './TileOrientedBoundingBox'
@@ -67,6 +69,7 @@ define([
         Transforms,
         ClearCommand,
         Pass,
+        RenderState,
         when,
         Axis,
         Cesium3DTile,
@@ -85,6 +88,7 @@ define([
         PointCloudShading,
         SceneMode,
         ShadowMode,
+        StencilConstants,
         TileBoundingRegion,
         TileBoundingSphere,
         TileOrientedBoundingBox) {
@@ -195,6 +199,7 @@ define([
 
         this._hasMixedContent = false;
 
+        this._stencilClearCommand = undefined;
         this._backfaceCommands = new ManagedArray();
 
         this._maximumScreenSpaceError = defaultValue(options.maximumScreenSpaceError, 16);
@@ -1703,11 +1708,6 @@ define([
         tileset._tileDebugLabels.update(frameState);
     }
 
-    var stencilClearCommand = new ClearCommand({
-        stencil : 0,
-        pass : Pass.CESIUM_3D_TILE
-    });
-
     function updateTiles(tileset, frameState) {
         tileset._styleEngine.applyStyle(tileset, frameState);
 
@@ -1729,7 +1729,16 @@ define([
         tileset._backfaceCommands.length = 0;
 
         if (bivariateVisibilityTest) {
-            commandList.push(stencilClearCommand);
+            if (!defined(tileset._stencilClearCommand)) {
+                tileset._stencilClearCommand = new ClearCommand({
+                    stencil : 0,
+                    pass : Pass.CESIUM_3D_TILE,
+                    renderState : RenderState.fromCache({
+                        stencilMask : StencilConstants.SKIP_LOD_MASK
+                    })
+                });
+            }
+            commandList.push(tileset._stencilClearCommand);
         }
 
         var lengthBeforeUpdate = commandList.length;

Source/Scene/Cesium3DTilesetTraversal.js

@@ -526,12 +526,8 @@ define([
      * the children's z-depth and the ancestor's z-depth. We cannot rely on Z because we want the child to appear on top
      * of ancestor regardless of true depth. The stencil tests used require children to be drawn first.
      *
-     * NOTE: this will no longer work when there is a chain of selected tiles that is longer than the size of the
-     * stencil buffer (usually 8 bits). In other words, the subset of the tree containing only selected tiles must be
-     * no deeper than 255. It is very, very unlikely this will cause a problem.
-     *
-     * NOTE: when the scene has inverted classification enabled, the stencil buffer will be masked to 4 bits. So, the
-     * selected tiles must be no deeper than 15. This is still very unlikely.
+     * NOTE: 3D Tiles uses 3 bits from the stencil buffer meaning this will not work when there is a chain of
+     * selected tiles that is deeper than 7. This is not very likely.
      */
     function traverseAndSelect(tileset, root, frameState) {
         var stack = selectionTraversal.stack;