ClassificationPrimitive.js

define([
        '../Core/ColorGeometryInstanceAttribute',
        '../Core/combine',
        '../Core/defaultValue',
        '../Core/defined',
        '../Core/defineProperties',
        '../Core/destroyObject',
        '../Core/DeveloperError',
        '../Core/GeometryInstance',
        '../Core/isArray',
        '../Renderer/DrawCommand',
        '../Renderer/Pass',
        '../Renderer/RenderState',
        '../Renderer/ShaderProgram',
        '../Renderer/ShaderSource',
        '../Shaders/ShadowVolumeFS',
        '../Shaders/ShadowVolumeAppearanceVS',
        '../ThirdParty/when',
        './BlendingState',
        './ClassificationType',
        './DepthFunction',
        './PerInstanceColorAppearance',
        './Primitive',
        './SceneMode',
        './ShadowVolumeAppearance',
        './StencilConstants',
        './StencilFunction',
        './StencilOperation'
    ], function(
        ColorGeometryInstanceAttribute,
        combine,
        defaultValue,
        defined,
        defineProperties,
        destroyObject,
        DeveloperError,
        GeometryInstance,
        isArray,
        DrawCommand,
        Pass,
        RenderState,
        ShaderProgram,
        ShaderSource,
        ShadowVolumeFS,
        ShadowVolumeAppearanceVS,
        when,
        BlendingState,
        ClassificationType,
        DepthFunction,
        PerInstanceColorAppearance,
        Primitive,
        SceneMode,
        ShadowVolumeAppearance,
        StencilConstants,
        StencilFunction,
        StencilOperation) {
    'use strict';

    var ClassificationPrimitiveReadOnlyInstanceAttributes = ['color'];

    /**
     * A classification primitive represents a volume enclosing geometry in the {@link Scene} to be highlighted.
     * <p>
     * A primitive combines geometry instances with an {@link Appearance} that describes the full shading, including
     * {@link Material} and {@link RenderState}.  Roughly, the geometry instance defines the structure and placement,
     * and the appearance defines the visual characteristics.  Decoupling geometry and appearance allows us to mix
     * and match most of them and add a new geometry or appearance independently of each other.
     * Only {@link PerInstanceColorAppearance} with the same color across all instances is supported at this time when using
     * ClassificationPrimitive directly.
     * For full {@link Appearance} support when classifying terrain or 3D Tiles use {@link GroundPrimitive} instead.
     * </p>
     * <p>
     * For correct rendering, this feature requires the EXT_frag_depth WebGL extension. For hardware that do not support this extension, there
     * will be rendering artifacts for some viewing angles.
     * </p>
     * <p>
     * Valid geometries are {@link BoxGeometry}, {@link CylinderGeometry}, {@link EllipsoidGeometry}, {@link PolylineVolumeGeometry}, and {@link SphereGeometry}.
     * </p>
     * <p>
     * Geometries that follow the surface of the ellipsoid, such as {@link CircleGeometry}, {@link CorridorGeometry}, {@link EllipseGeometry}, {@link PolygonGeometry}, and {@link RectangleGeometry},
     * are also valid if they are extruded volumes; otherwise, they will not be rendered.
     * </p>
     *
     * @alias ClassificationPrimitive
     * @constructor
     *
     * @param {Object} [options] Object with the following properties:
     * @param {Array|GeometryInstance} [options.geometryInstances] The geometry instances to render. This can either be a single instance or an array of length one.
     * @param {Appearance} [options.appearance] The appearance used to render the primitive. Defaults to PerInstanceColorAppearance when GeometryInstances have a color attribute.
     * @param {Boolean} [options.show=true] Determines if this primitive will be shown.
     * @param {Boolean} [options.vertexCacheOptimize=false] When <code>true</code>, geometry vertices are optimized for the pre and post-vertex-shader caches.
     * @param {Boolean} [options.interleave=false] When <code>true</code>, geometry vertex attributes are interleaved, which can slightly improve rendering performance but increases load time.
     * @param {Boolean} [options.compressVertices=true] When <code>true</code>, the geometry vertices are compressed, which will save memory.
     * @param {Boolean} [options.releaseGeometryInstances=true] When <code>true</code>, the primitive does not keep a reference to the input <code>geometryInstances</code> to save memory.
     * @param {Boolean} [options.allowPicking=true] When <code>true</code>, each geometry instance will only be pickable with {@link Scene#pick}.  When <code>false</code>, GPU memory is saved.
     * @param {Boolean} [options.asynchronous=true] Determines if the primitive will be created asynchronously or block until ready. If false initializeTerrainHeights() must be called first.
     * @param {ClassificationType} [options.classificationType=ClassificationType.BOTH] Determines whether terrain, 3D Tiles or both will be classified.
     * @param {Boolean} [options.debugShowBoundingVolume=false] For debugging only. Determines if this primitive's commands' bounding spheres are shown.
     * @param {Boolean} [options.debugShowShadowVolume=false] For debugging only. Determines if the shadow volume for each geometry in the primitive is drawn. Must be <code>true</code> on
     *                  creation for the volumes to be created before the geometry is released or options.releaseGeometryInstance must be <code>false</code>.
     *
     * @see Primitive
     * @see GroundPrimitive
     * @see GeometryInstance
     * @see Appearance
     */
    function ClassificationPrimitive(options) {
        options = defaultValue(options, defaultValue.EMPTY_OBJECT);
        var geometryInstances = options.geometryInstances;

        /**
         * The geometry instance rendered with this primitive.  This may
         * be <code>undefined</code> if <code>options.releaseGeometryInstances</code>
         * is <code>true</code> when the primitive is constructed.
         * <p>
         * Changing this property after the primitive is rendered has no effect.
         * </p>
         * <p>
         * Because of the rendering technique used, all geometry instances must be the same color.
         * If there is an instance with a differing color, a <code>DeveloperError</code> will be thrown
         * on the first attempt to render.
         * </p>
         *
         * @readonly
         * @type {Array|GeometryInstance}
         *
         * @default undefined
         */
        this.geometryInstances = geometryInstances;
        /**
         * Determines if the primitive will be shown.  This affects all geometry
         * instances in the primitive.
         *
         * @type {Boolean}
         *
         * @default true
         */
        this.show = defaultValue(options.show, true);
        /**
         * Determines whether terrain, 3D Tiles or both will be classified.
         *
         * @type {ClassificationType}
         *
         * @default ClassificationType.BOTH
         */
        this.classificationType = defaultValue(options.classificationType, ClassificationType.BOTH);
        /**
         * This property is for debugging only; it is not for production use nor is it optimized.
         * <p>
         * Draws the bounding sphere for each draw command in the primitive.
         * </p>
         *
         * @type {Boolean}
         *
         * @default false
         */
        this.debugShowBoundingVolume = defaultValue(options.debugShowBoundingVolume, false);
        /**
         * This property is for debugging only; it is not for production use nor is it optimized.
         * <p>
         * Draws the shadow volume for each geometry in the primitive.
         * </p>
         *
         * @type {Boolean}
         *
         * @default false
         */
        this.debugShowShadowVolume = defaultValue(options.debugShowShadowVolume, false);
        this._debugShowShadowVolume = false;

        // These are used by GroundPrimitive to augment the shader and uniform map.
        this._extruded = defaultValue(options._extruded, false);
        this._uniformMap = options._uniformMap;

        this._sp = undefined;
        this._spStencil = undefined;
        this._spPick = undefined;
        this._spColor = undefined;

        this._spPick2D = undefined; // only derived if necessary
        this._spColor2D = undefined; // only derived if necessary

        this._rsStencilPreloadPass = undefined;
        this._rsStencilPreloadPass3DTiles = undefined;
        this._rsStencilDepthPass = undefined;
        this._rsStencilDepthPass3DTiles = undefined;
        this._rsColorPass = undefined;
        this._rsPickPass = undefined;

        this._commandsIgnoreShow = [];

        this._ready = false;
        this._readyPromise = when.defer();

        this._primitive = undefined;
        this._pickPrimitive = options._pickPrimitive;

        // Set in update
        this._hasSphericalExtentsAttribute = false;
        this._hasPlanarExtentsAttributes = false;
        this._hasPerColorAttribute = false;

        this.appearance = options.appearance;

        var readOnlyAttributes;
        if (defined(geometryInstances) && isArray(geometryInstances) && geometryInstances.length > 1) {
            readOnlyAttributes = ClassificationPrimitiveReadOnlyInstanceAttributes;
        }

        this._createBoundingVolumeFunction = options._createBoundingVolumeFunction;
        this._updateAndQueueCommandsFunction = options._updateAndQueueCommandsFunction;

        this._usePickOffsets = false;

        this._primitiveOptions = {
            geometryInstances : undefined,
            appearance : undefined,
            vertexCacheOptimize : defaultValue(options.vertexCacheOptimize, false),
            interleave : defaultValue(options.interleave, false),
            releaseGeometryInstances : defaultValue(options.releaseGeometryInstances, true),
            allowPicking : defaultValue(options.allowPicking, true),
            asynchronous : defaultValue(options.asynchronous, true),
            compressVertices : defaultValue(options.compressVertices, true),
            _readOnlyInstanceAttributes : readOnlyAttributes,
            _createBoundingVolumeFunction : undefined,
            _createRenderStatesFunction : undefined,
            _createShaderProgramFunction : undefined,
            _createCommandsFunction : undefined,
            _updateAndQueueCommandsFunction : undefined,
            _createPickOffsets : true
        };
    }

    defineProperties(ClassificationPrimitive.prototype, {
        /**
         * When <code>true</code>, geometry vertices are optimized for the pre and post-vertex-shader caches.
         *
         * @memberof ClassificationPrimitive.prototype
         *
         * @type {Boolean}
         * @readonly
         *
         * @default true
         */
        vertexCacheOptimize : {
            get : function() {
                return this._primitiveOptions.vertexCacheOptimize;
            }
        },

        /**
         * Determines if geometry vertex attributes are interleaved, which can slightly improve rendering performance.
         *
         * @memberof ClassificationPrimitive.prototype
         *
         * @type {Boolean}
         * @readonly
         *
         * @default false
         */
        interleave : {
            get : function() {
                return this._primitiveOptions.interleave;
            }
        },

        /**
         * When <code>true</code>, the primitive does not keep a reference to the input <code>geometryInstances</code> to save memory.
         *
         * @memberof ClassificationPrimitive.prototype
         *
         * @type {Boolean}
         * @readonly
         *
         * @default true
         */
        releaseGeometryInstances : {
            get : function() {
                return this._primitiveOptions.releaseGeometryInstances;
            }
        },

        /**
         * When <code>true</code>, each geometry instance will only be pickable with {@link Scene#pick}.  When <code>false</code>, GPU memory is saved.
         *
         * @memberof ClassificationPrimitive.prototype
         *
         * @type {Boolean}
         * @readonly
         *
         * @default true
         */
        allowPicking : {
            get : function() {
                return this._primitiveOptions.allowPicking;
            }
        },

        /**
         * Determines if the geometry instances will be created and batched on a web worker.
         *
         * @memberof ClassificationPrimitive.prototype
         *
         * @type {Boolean}
         * @readonly
         *
         * @default true
         */
        asynchronous : {
            get : function() {
                return this._primitiveOptions.asynchronous;
            }
        },

        /**
         * When <code>true</code>, geometry vertices are compressed, which will save memory.
         *
         * @memberof ClassificationPrimitive.prototype
         *
         * @type {Boolean}
         * @readonly
         *
         * @default true
         */
        compressVertices : {
            get : function() {
                return this._primitiveOptions.compressVertices;
            }
        },

        /**
         * Determines if the primitive is complete and ready to render.  If this property is
         * true, the primitive will be rendered the next time that {@link ClassificationPrimitive#update}
         * is called.
         *
         * @memberof ClassificationPrimitive.prototype
         *
         * @type {Boolean}
         * @readonly
         */
        ready : {
            get : function() {
                return this._ready;
            }
        },

        /**
         * Gets a promise that resolves when the primitive is ready to render.
         * @memberof ClassificationPrimitive.prototype
         * @type {Promise.<ClassificationPrimitive>}
         * @readonly
         */
        readyPromise : {
            get : function() {
                return this._readyPromise.promise;
            }
        },

        /**
         * Returns true if the ClassificationPrimitive needs a separate shader and commands for 2D.
         * This is because texture coordinates on ClassificationPrimitives are computed differently,
         * and are used for culling when multiple GeometryInstances are batched in one ClassificationPrimitive.
         * @memberof ClassificationPrimitive.prototype
         * @type {Boolean}
         * @readonly
         * @private
         */
        _needs2DShader : {
            get : function() {
                return this._hasPlanarExtentsAttributes || this._hasSphericalExtentsAttribute;
            }
        }
    });

    /**
     * Determines if ClassificationPrimitive rendering is supported.
     *
     * @param {Scene} scene The scene.
     * @returns {Boolean} <code>true</code> if ClassificationPrimitives are supported; otherwise, returns <code>false</code>
     */
    ClassificationPrimitive.isSupported = function(scene) {
        return scene.context.stencilBuffer;
    };

    function getStencilPreloadRenderState(enableStencil, mask3DTiles) {
        var stencilFunction = mask3DTiles ? StencilFunction.EQUAL : StencilFunction.ALWAYS;
        return {
            colorMask : {
                red : false,
                green : false,
                blue : false,
                alpha : false
            },
            stencilTest : {
                enabled : enableStencil,
                frontFunction : stencilFunction,
                frontOperation : {
                    fail : StencilOperation.KEEP,
                    zFail : StencilOperation.DECREMENT_WRAP,
                    zPass : StencilOperation.DECREMENT_WRAP
                },
                backFunction : stencilFunction,
                backOperation : {
                    fail : StencilOperation.KEEP,
                    zFail : StencilOperation.INCREMENT_WRAP,
                    zPass : StencilOperation.INCREMENT_WRAP
                },
                reference : StencilConstants.CESIUM_3D_TILE_MASK,
                mask : StencilConstants.CESIUM_3D_TILE_MASK
            },
            stencilMask : StencilConstants.CLASSIFICATION_MASK,
            depthTest : {
                enabled : false
            },
            depthMask : false
        };
    }

    function getStencilDepthRenderState(enableStencil, mask3DTiles) {
        var stencilFunction = mask3DTiles ? StencilFunction.EQUAL : StencilFunction.ALWAYS;
        return {
            colorMask : {
                red : false,
                green : false,
                blue : false,
                alpha : false
            },
            stencilTest : {
                enabled : enableStencil,
                frontFunction : stencilFunction,
                frontOperation : {
                    fail : StencilOperation.KEEP,
                    zFail : StencilOperation.KEEP,
                    zPass : StencilOperation.INCREMENT_WRAP
                },
                backFunction : stencilFunction,
                backOperation : {
                    fail : StencilOperation.KEEP,
                    zFail : StencilOperation.KEEP,
                    zPass : StencilOperation.DECREMENT_WRAP
                },
                reference : StencilConstants.CESIUM_3D_TILE_MASK,
                mask : StencilConstants.CESIUM_3D_TILE_MASK
            },
            stencilMask : StencilConstants.CLASSIFICATION_MASK,
            depthTest : {
                enabled : true,
                func : DepthFunction.LESS_OR_EQUAL
            },
            depthMask : false
        };
    }

    function getColorRenderState(enableStencil) {
        return {
            stencilTest : {
                enabled : enableStencil,
                frontFunction : StencilFunction.NOT_EQUAL,
                frontOperation : {
                    fail : StencilOperation.KEEP,
                    zFail : StencilOperation.KEEP,
                    zPass : StencilOperation.DECREMENT_WRAP
                },
                backFunction : StencilFunction.NOT_EQUAL,
                backOperation : {
                    fail : StencilOperation.KEEP,
                    zFail : StencilOperation.KEEP,
                    zPass : StencilOperation.DECREMENT_WRAP
                },
                reference : 0,
                mask : StencilConstants.CLASSIFICATION_MASK
            },
            stencilMask : StencilConstants.CLASSIFICATION_MASK,
            depthTest : {
                enabled : false
            },
            depthMask : false,
            blending : BlendingState.ALPHA_BLEND
        };
    }

    var pickRenderState = {
        stencilTest : {
            enabled : true,
            frontFunction : StencilFunction.NOT_EQUAL,
            frontOperation : {
                fail : StencilOperation.KEEP,
                zFail : StencilOperation.KEEP,
                zPass : StencilOperation.DECREMENT_WRAP
            },
            backFunction : StencilFunction.NOT_EQUAL,
            backOperation : {
                fail : StencilOperation.KEEP,
                zFail : StencilOperation.KEEP,
                zPass : StencilOperation.DECREMENT_WRAP
            },
            reference : 0,
            mask : StencilConstants.CLASSIFICATION_MASK
        },
        stencilMask : StencilConstants.CLASSIFICATION_MASK,
        depthTest : {
            enabled : false
        },
        depthMask : false
    };

    function createRenderStates(classificationPrimitive, context, appearance, twoPasses) {
        if (defined(classificationPrimitive._rsStencilPreloadPass)) {
            return;
        }
        var stencilEnabled = !classificationPrimitive.debugShowShadowVolume;

        classificationPrimitive._rsStencilPreloadPass = RenderState.fromCache(getStencilPreloadRenderState(stencilEnabled, false));
        classificationPrimitive._rsStencilPreloadPass3DTiles = RenderState.fromCache(getStencilPreloadRenderState(stencilEnabled, true));
        classificationPrimitive._rsStencilDepthPass = RenderState.fromCache(getStencilDepthRenderState(stencilEnabled, false));
        classificationPrimitive._rsStencilDepthPass3DTiles = RenderState.fromCache(getStencilDepthRenderState(stencilEnabled, true));
        classificationPrimitive._rsColorPass = RenderState.fromCache(getColorRenderState(stencilEnabled, false));
        classificationPrimitive._rsPickPass = RenderState.fromCache(pickRenderState);
    }

    function modifyForEncodedNormals(primitive, vertexShaderSource) {
        if (!primitive.compressVertices) {
            return vertexShaderSource;
        }

        if (vertexShaderSource.search(/attribute\s+vec3\s+extrudeDirection;/g) !== -1) {
            var attributeName = 'compressedAttributes';

            //only shadow volumes use extrudeDirection, and shadow volumes use vertexFormat: POSITION_ONLY so we don't need to check other attributes
            var attributeDecl = 'attribute vec2 ' + attributeName + ';';

            var globalDecl = 'vec3 extrudeDirection;\n';
            var decode = '    extrudeDirection = czm_octDecode(' + attributeName + ', 65535.0);\n';

            var modifiedVS = vertexShaderSource;
            modifiedVS = modifiedVS.replace(/attribute\s+vec3\s+extrudeDirection;/g, '');
            modifiedVS = ShaderSource.replaceMain(modifiedVS, 'czm_non_compressed_main');
            var compressedMain =
                'void main() \n' +
                '{ \n' +
                decode +
                '    czm_non_compressed_main(); \n' +
                '}';

            return [attributeDecl, globalDecl, modifiedVS, compressedMain].join('\n');
        }
    }

    function createShaderProgram(classificationPrimitive, frameState) {
        var context = frameState.context;
        var primitive = classificationPrimitive._primitive;
        var vs = ShadowVolumeAppearanceVS;
        vs = classificationPrimitive._primitive._batchTable.getVertexShaderCallback()(vs);
        vs = Primitive._appendDistanceDisplayConditionToShader(primitive, vs);
        vs = Primitive._modifyShaderPosition(classificationPrimitive, vs, frameState.scene3DOnly);
        vs = Primitive._updateColorAttribute(primitive, vs);

        var planarExtents = classificationPrimitive._hasPlanarExtentsAttributes;
        var cullFragmentsUsingExtents = planarExtents || classificationPrimitive._hasSphericalExtentsAttribute;

        if (classificationPrimitive._extruded) {
            vs = modifyForEncodedNormals(primitive, vs);
        }

        var extrudedDefine = classificationPrimitive._extruded ? 'EXTRUDED_GEOMETRY' : '';
        // Tesselation on ClassificationPrimitives tends to be low,
        // which causes problems when interpolating log depth from vertices.
        // So force computing and writing logarithmic depth in the fragment shader.
        // Re-enable at far distances to avoid z-fighting.
        var disableGlPositionLogDepth = 'ENABLE_GL_POSITION_LOG_DEPTH_AT_HEIGHT';

        var vsSource = new ShaderSource({
            defines : [extrudedDefine, disableGlPositionLogDepth],
            sources : [vs]
        });
        var fsSource = new ShaderSource({
            sources : [ShadowVolumeFS]
        });
        var attributeLocations = classificationPrimitive._primitive._attributeLocations;

        var shadowVolumeAppearance = new ShadowVolumeAppearance(cullFragmentsUsingExtents, planarExtents, classificationPrimitive.appearance);

        classificationPrimitive._spStencil = ShaderProgram.replaceCache({
            context : context,
            shaderProgram : classificationPrimitive._spStencil,
            vertexShaderSource : vsSource,
            fragmentShaderSource : fsSource,
            attributeLocations : attributeLocations
        });

        if (classificationPrimitive._primitive.allowPicking) {
            var vsPick = ShaderSource.createPickVertexShaderSource(vs);
            vsPick = Primitive._appendShowToShader(primitive, vsPick);
            vsPick = Primitive._updatePickColorAttribute(vsPick);

            var pickFS3D = shadowVolumeAppearance.createPickFragmentShader(false);
            var pickVS3D = shadowVolumeAppearance.createPickVertexShader([extrudedDefine, disableGlPositionLogDepth], vsPick, false, frameState.mapProjection);

            classificationPrimitive._spPick = ShaderProgram.replaceCache({
                context : context,
                shaderProgram : classificationPrimitive._spPick,
                vertexShaderSource : pickVS3D,
                fragmentShaderSource : pickFS3D,
                attributeLocations : attributeLocations
            });

            // Derive a 2D pick shader if the primitive uses texture coordinate-based fragment culling,
            // since texture coordinates are computed differently in 2D.
            if (cullFragmentsUsingExtents) {
                var pickProgram2D = context.shaderCache.getDerivedShaderProgram(classificationPrimitive._spPick, '2dPick');
                if (!defined(pickProgram2D)) {
                    var pickFS2D = shadowVolumeAppearance.createPickFragmentShader(true);
                    var pickVS2D = shadowVolumeAppearance.createPickVertexShader([extrudedDefine, disableGlPositionLogDepth], vsPick, true, frameState.mapProjection);

                    pickProgram2D = context.shaderCache.createDerivedShaderProgram(classificationPrimitive._spPick, '2dPick', {
                        vertexShaderSource : pickVS2D,
                        fragmentShaderSource : pickFS2D,
                        attributeLocations : attributeLocations
                    });
                }
                classificationPrimitive._spPick2D = pickProgram2D;
            }
        } else {
            classificationPrimitive._spPick = ShaderProgram.fromCache({
                context : context,
                vertexShaderSource : vsSource,
                fragmentShaderSource : fsSource,
                attributeLocations : attributeLocations
            });
        }

        vs = Primitive._appendShowToShader(primitive, vs);
        vsSource = new ShaderSource({
            defines : [extrudedDefine, disableGlPositionLogDepth],
            sources : [vs]
        });

        classificationPrimitive._sp = ShaderProgram.replaceCache({
            context : context,
            shaderProgram : classificationPrimitive._sp,
            vertexShaderSource : vsSource,
            fragmentShaderSource : fsSource,
            attributeLocations : attributeLocations
        });

        // Create a fragment shader that computes only required material hookups using screen space techniques
        var fsColorSource = shadowVolumeAppearance.createFragmentShader(false);
        var vsColorSource = shadowVolumeAppearance.createVertexShader([extrudedDefine, disableGlPositionLogDepth], vs, false, frameState.mapProjection);

        classificationPrimitive._spColor = ShaderProgram.replaceCache({
            context : context,
            shaderProgram : classificationPrimitive._spColor,
            vertexShaderSource : vsColorSource,
            fragmentShaderSource : fsColorSource,
            attributeLocations : attributeLocations
        });

        // Derive a 2D shader if the primitive uses texture coordinate-based fragment culling,
        // since texture coordinates are computed differently in 2D.
        // Any material that uses texture coordinates will also equip texture coordinate-based fragment culling.
        if (cullFragmentsUsingExtents) {
            var colorProgram2D = context.shaderCache.getDerivedShaderProgram(classificationPrimitive._spColor, '2dColor');
            if (!defined(colorProgram2D)) {
                var fsColorSource2D = shadowVolumeAppearance.createFragmentShader(true);
                var vsColorSource2D = shadowVolumeAppearance.createVertexShader([extrudedDefine, disableGlPositionLogDepth], vs, true, frameState.mapProjection);

                colorProgram2D = context.shaderCache.createDerivedShaderProgram(classificationPrimitive._spColor, '2dColor', {
                    vertexShaderSource : vsColorSource2D,
                    fragmentShaderSource : fsColorSource2D,
                    attributeLocations : attributeLocations
                });
            }
            classificationPrimitive._spColor2D = colorProgram2D;
        }
    }

    function createColorCommands(classificationPrimitive, colorCommands) {
        var primitive = classificationPrimitive._primitive;
        var length = primitive._va.length * 3; // each geometry (pack of vertex attributes) needs 3 commands: front/back stencils and fill
        colorCommands.length = length;

        var i;
        var command;
        var derivedCommand;
        var vaIndex = 0;
        var uniformMap = primitive._batchTable.getUniformMapCallback()(classificationPrimitive._uniformMap);

        var needs2DShader = classificationPrimitive._needs2DShader;

        for (i = 0; i < length; i += 3) {
            var vertexArray = primitive._va[vaIndex++];

            // Stencil preload command
            command = colorCommands[i];
            if (!defined(command)) {
                command = colorCommands[i] = new DrawCommand({
                    owner : classificationPrimitive,
                    primitiveType : primitive._primitiveType
                });
            }

            command.vertexArray = vertexArray;
            command.renderState = classificationPrimitive._rsStencilPreloadPass;
            command.shaderProgram = classificationPrimitive._sp;
            command.uniformMap = uniformMap;
            command.pass = Pass.TERRAIN_CLASSIFICATION;

            derivedCommand = DrawCommand.shallowClone(command, command.derivedCommands.tileset);
            derivedCommand.renderState = classificationPrimitive._rsStencilPreloadPass3DTiles;
            derivedCommand.pass = Pass.CESIUM_3D_TILE_CLASSIFICATION;
            command.derivedCommands.tileset = derivedCommand;

            // Stencil depth command
            command = colorCommands[i + 1];
            if (!defined(command)) {
                command = colorCommands[i + 1] = new DrawCommand({
                    owner : classificationPrimitive,
                    primitiveType : primitive._primitiveType
                });
            }

            command.vertexArray = vertexArray;
            command.renderState = classificationPrimitive._rsStencilDepthPass;
            command.shaderProgram = classificationPrimitive._sp;
            command.uniformMap = uniformMap;
            command.pass = Pass.TERRAIN_CLASSIFICATION;

            derivedCommand = DrawCommand.shallowClone(command, command.derivedCommands.tileset);
            derivedCommand.renderState = classificationPrimitive._rsStencilDepthPass3DTiles;
            derivedCommand.pass = Pass.CESIUM_3D_TILE_CLASSIFICATION;
            command.derivedCommands.tileset = derivedCommand;

            // Color command
            command = colorCommands[i + 2];
            if (!defined(command)) {
                command = colorCommands[i + 2] = new DrawCommand({
                    owner : classificationPrimitive,
                    primitiveType : primitive._primitiveType
                });
            }

            command.vertexArray = vertexArray;
            command.renderState = classificationPrimitive._rsColorPass;
            command.shaderProgram = classificationPrimitive._spColor;
            command.pass = Pass.TERRAIN_CLASSIFICATION;

            var appearance = classificationPrimitive.appearance;
            var material = appearance.material;
            if (defined(material)) {
                uniformMap = combine(uniformMap, material._uniforms);
            }

            command.uniformMap = uniformMap;

            derivedCommand = DrawCommand.shallowClone(command, command.derivedCommands.tileset);
            derivedCommand.pass = Pass.CESIUM_3D_TILE_CLASSIFICATION;
            command.derivedCommands.tileset = derivedCommand;

            // Derive for 2D if texture coordinates are ever computed
            if (needs2DShader) {
                // First derive from the terrain command
                var derived2DCommand = DrawCommand.shallowClone(command, command.derivedCommands.appearance2D);
                derived2DCommand.shaderProgram = classificationPrimitive._spColor2D;
                command.derivedCommands.appearance2D = derived2DCommand;

                // Then derive from the 3D Tiles command
                derived2DCommand = DrawCommand.shallowClone(derivedCommand, derivedCommand.derivedCommands.appearance2D);
                derived2DCommand.shaderProgram = classificationPrimitive._spColor2D;
                derived2DCommand.pass = Pass.CESIUM_3D_TILE_CLASSIFICATION;
                derivedCommand.derivedCommands.appearance2D = derived2DCommand;
            }
        }

        var commandsIgnoreShow = classificationPrimitive._commandsIgnoreShow;
        var spStencil = classificationPrimitive._spStencil;

        var commandIndex = 0;
        length = commandsIgnoreShow.length = length / 3 * 2;

        for (var j = 0; j < length; j += 2) {
            var commandIgnoreShow = commandsIgnoreShow[j] = DrawCommand.shallowClone(colorCommands[commandIndex], commandsIgnoreShow[j]);
            commandIgnoreShow.shaderProgram = spStencil;
            commandIgnoreShow.pass = Pass.CESIUM_3D_TILE_CLASSIFICATION_IGNORE_SHOW;

            commandIgnoreShow = commandsIgnoreShow[j + 1] = DrawCommand.shallowClone(colorCommands[commandIndex + 1], commandsIgnoreShow[j + 1]);
            commandIgnoreShow.shaderProgram = spStencil;
            commandIgnoreShow.pass = Pass.CESIUM_3D_TILE_CLASSIFICATION_IGNORE_SHOW;

            commandIndex += 3;
        }
    }

    function createPickCommands(classificationPrimitive, pickCommands) {
        var usePickOffsets = classificationPrimitive._usePickOffsets;

        var primitive = classificationPrimitive._primitive;
        var length = primitive._va.length * 3; // each geometry (pack of vertex attributes) needs 3 commands: front/back stencils and fill

        // Fallback for batching same-color geometry instances
        var pickOffsets;
        var pickIndex = 0;
        var pickOffset;
        if (usePickOffsets) {
            pickOffsets = primitive._pickOffsets;
            length = pickOffsets.length * 3;
        }

        pickCommands.length = length;

        var j;
        var command;
        var derivedCommand;
        var vaIndex = 0;
        var uniformMap = primitive._batchTable.getUniformMapCallback()(classificationPrimitive._uniformMap);

        var needs2DShader = classificationPrimitive._needs2DShader;

        for (j = 0; j < length; j += 3) {
            var vertexArray = primitive._va[vaIndex++];
            if (usePickOffsets) {
                pickOffset = pickOffsets[pickIndex++];
                vertexArray = primitive._va[pickOffset.index];
            }

            // Stencil preload command
            command = pickCommands[j];
            if (!defined(command)) {
                command = pickCommands[j] = new DrawCommand({
                    owner : classificationPrimitive,
                    primitiveType : primitive._primitiveType,
                    pickOnly : true
                });
            }

            command.vertexArray = vertexArray;
            command.renderState = classificationPrimitive._rsStencilPreloadPass;
            command.shaderProgram = classificationPrimitive._sp;
            command.uniformMap = uniformMap;
            command.pass = Pass.TERRAIN_CLASSIFICATION;
            if (usePickOffsets) {
                command.offset = pickOffset.offset;
                command.count = pickOffset.count;
            }

            // Derive for 3D Tiles classification
            derivedCommand = DrawCommand.shallowClone(command, command.derivedCommands.tileset);
            derivedCommand.renderState = classificationPrimitive._rsStencilPreloadPass3DTiles;
            derivedCommand.pass = Pass.CESIUM_3D_TILE_CLASSIFICATION;
            command.derivedCommands.tileset = derivedCommand;

            // Stencil depth command
            command = pickCommands[j + 1];
            if (!defined(command)) {
                command = pickCommands[j + 1] = new DrawCommand({
                    owner : classificationPrimitive,
                    primitiveType : primitive._primitiveType,
                    pickOnly : true
                });
            }

            command.vertexArray = vertexArray;
            command.renderState = classificationPrimitive._rsStencilDepthPass;
            command.shaderProgram = classificationPrimitive._sp;
            command.uniformMap = uniformMap;
            command.pass = Pass.TERRAIN_CLASSIFICATION;
            if (usePickOffsets) {
                command.offset = pickOffset.offset;
                command.count = pickOffset.count;
            }

            // Derive for 3D Tiles classification
            derivedCommand = DrawCommand.shallowClone(command, command.derivedCommands.tileset);
            derivedCommand.renderState = classificationPrimitive._rsStencilDepthPass3DTiles;
            derivedCommand.pass = Pass.CESIUM_3D_TILE_CLASSIFICATION;
            command.derivedCommands.tileset = derivedCommand;

            // Pick color command
            command = pickCommands[j + 2];
            if (!defined(command)) {
                command = pickCommands[j + 2] = new DrawCommand({
                    owner : classificationPrimitive,
                    primitiveType : primitive._primitiveType,
                    pickOnly : true
                });
            }

            command.vertexArray = vertexArray;
            command.renderState = classificationPrimitive._rsPickPass;
            command.shaderProgram = classificationPrimitive._spPick;
            command.uniformMap = uniformMap;
            command.pass = Pass.TERRAIN_CLASSIFICATION;
            if (usePickOffsets) {
                command.offset = pickOffset.offset;
                command.count = pickOffset.count;
            }

            derivedCommand = DrawCommand.shallowClone(command, command.derivedCommands.tileset);
            derivedCommand.pass = Pass.CESIUM_3D_TILE_CLASSIFICATION;
            command.derivedCommands.tileset = derivedCommand;

            // Derive for 2D if texture coordinates are ever computed
            if (needs2DShader) {
                // First derive from the terrain command
                var derived2DCommand = DrawCommand.shallowClone(command, command.derivedCommands.pick2D);
                derived2DCommand.shaderProgram = classificationPrimitive._spPick2D;
                command.derivedCommands.pick2D = derived2DCommand;

                // Then derive from the 3D Tiles command
                derived2DCommand = DrawCommand.shallowClone(derivedCommand, derivedCommand.derivedCommands.pick2D);
                derived2DCommand.shaderProgram = classificationPrimitive._spPick2D;
                derived2DCommand.pass = Pass.CESIUM_3D_TILE_CLASSIFICATION;
                derivedCommand.derivedCommands.pick2D = derived2DCommand;
            }
        }
    }

    function createCommands(classificationPrimitive, appearance, material, translucent, twoPasses, colorCommands, pickCommands) {
        createColorCommands(classificationPrimitive, colorCommands);
        createPickCommands(classificationPrimitive, pickCommands);
    }

    function boundingVolumeIndex(commandIndex, length) {
        return Math.floor((commandIndex % length) / 3);
    }

    function updateAndQueueRenderCommand(command, frameState, modelMatrix, cull, boundingVolume, debugShowBoundingVolume) {
        command.modelMatrix = modelMatrix;
        command.boundingVolume = boundingVolume;
        command.cull = cull;
        command.debugShowBoundingVolume = debugShowBoundingVolume;

        frameState.commandList.push(command);
    }

    function updateAndQueuePickCommand(command, frameState, modelMatrix, cull, boundingVolume) {
        command.modelMatrix = modelMatrix;
        command.boundingVolume = boundingVolume;
        command.cull = cull;

        frameState.commandList.push(command);
    }

    function updateAndQueueCommands(classificationPrimitive, frameState, colorCommands, pickCommands, modelMatrix, cull, debugShowBoundingVolume, twoPasses) {
        var primitive = classificationPrimitive._primitive;
        Primitive._updateBoundingVolumes(primitive, frameState, modelMatrix);

        var boundingVolumes;
        if (frameState.mode === SceneMode.SCENE3D) {
            boundingVolumes = primitive._boundingSphereWC;
        } else if (frameState.mode === SceneMode.COLUMBUS_VIEW) {
            boundingVolumes = primitive._boundingSphereCV;
        } else if (frameState.mode === SceneMode.SCENE2D && defined(primitive._boundingSphere2D)) {
            boundingVolumes = primitive._boundingSphere2D;
        } else if (defined(primitive._boundingSphereMorph)) {
            boundingVolumes = primitive._boundingSphereMorph;
        }

        var classificationType = classificationPrimitive.classificationType;
        var queueTerrainCommands = (classificationType !== ClassificationType.CESIUM_3D_TILE);
        var queue3DTilesCommands = (classificationType !== ClassificationType.TERRAIN);

        var passes = frameState.passes;

        var i;
        var boundingVolume;
        var command;

        if (passes.render) {
            var colorLength = colorCommands.length;
            for (i = 0; i < colorLength; ++i) {
                boundingVolume = boundingVolumes[boundingVolumeIndex(i, colorLength)];
                if (queueTerrainCommands) {
                    command = colorCommands[i];
                    updateAndQueueRenderCommand(command, frameState, modelMatrix, cull, boundingVolume, debugShowBoundingVolume);
                }
                if (queue3DTilesCommands) {
                    command = colorCommands[i].derivedCommands.tileset;
                    updateAndQueueRenderCommand(command, frameState, modelMatrix, cull, boundingVolume, debugShowBoundingVolume);
                }
            }

            if (frameState.invertClassification) {
                var ignoreShowCommands = classificationPrimitive._commandsIgnoreShow;
                var ignoreShowCommandsLength = ignoreShowCommands.length;
                for (i = 0; i < ignoreShowCommandsLength; ++i) {
                    boundingVolume = boundingVolumes[Math.floor(i / 2)];
                    command = ignoreShowCommands[i];
                    updateAndQueueRenderCommand(command, frameState, modelMatrix, cull, boundingVolume, debugShowBoundingVolume);
                }
            }
        }

        if (passes.pick) {
            var pickLength = pickCommands.length;
            var pickOffsets = primitive._pickOffsets;
            for (i = 0; i < pickLength; ++i) {
                var pickOffset = pickOffsets[boundingVolumeIndex(i, pickLength)];
                boundingVolume = boundingVolumes[pickOffset.index];
                if (queueTerrainCommands) {
                    command = pickCommands[i];
                    updateAndQueuePickCommand(command, frameState, modelMatrix, cull, boundingVolume);
                }
                if (queue3DTilesCommands) {
                    command = pickCommands[i].derivedCommands.tileset;
                    updateAndQueuePickCommand(command, frameState, modelMatrix, cull, boundingVolume);
                }
            }
        }
    }

    /**
     * Called when {@link Viewer} or {@link CesiumWidget} render the scene to
     * get the draw commands needed to render this primitive.
     * <p>
     * Do not call this function directly.  This is documented just to
     * list the exceptions that may be propagated when the scene is rendered:
     * </p>
     *
     * @exception {DeveloperError} All instance geometries must have the same primitiveType.
     * @exception {DeveloperError} Appearance and material have a uniform with the same name.
     * @exception {DeveloperError} Not all of the geometry instances have the same color attribute.
     */
    ClassificationPrimitive.prototype.update = function(frameState) {
        if (!defined(this._primitive) && !defined(this.geometryInstances)) {
            return;
        }

        var appearance = this.appearance;
        if (defined(appearance) && defined(appearance.material)) {
            appearance.material.update(frameState.context);
        }

        var that = this;
        var primitiveOptions = this._primitiveOptions;

        if (!defined(this._primitive)) {
            var instances = isArray(this.geometryInstances) ? this.geometryInstances : [this.geometryInstances];
            var length = instances.length;

            var i;
            var instance;
            var attributes;

            var hasPerColorAttribute = false;
            var allColorsSame = true;
            var firstColor;
            var hasSphericalExtentsAttribute = false;
            var hasPlanarExtentsAttributes = false;

            if (length > 0) {
                attributes = instances[0].attributes;
                // Not expecting these to be set by users, should only be set via GroundPrimitive.
                // So don't check for mismatch.
                hasSphericalExtentsAttribute = ShadowVolumeAppearance.hasAttributesForSphericalExtents(attributes);
                hasPlanarExtentsAttributes = ShadowVolumeAppearance.hasAttributesForTextureCoordinatePlanes(attributes);
                firstColor = attributes.color;
            }

            for (i = 0; i < length; i++) {
                instance = instances[i];
                var color = instance.attributes.color;
                if (defined(color)) {
                    hasPerColorAttribute = true;
                }
                //>>includeStart('debug', pragmas.debug);
                else if (hasPerColorAttribute) {
                    throw new DeveloperError('All GeometryInstances must have color attributes to use per-instance color.');
                }
                //>>includeEnd('debug');

                allColorsSame = allColorsSame && defined(color) && ColorGeometryInstanceAttribute.equals(firstColor, color);
            }

            // If no attributes exist for computing spherical extents or fragment culling,
            // throw if the colors aren't all the same.
            if (!allColorsSame && !hasSphericalExtentsAttribute && !hasPlanarExtentsAttributes) {
                throw new DeveloperError('All GeometryInstances must have the same color attribute except via GroundPrimitives');
            }

            // default to a color appearance
            if (hasPerColorAttribute && !defined(appearance)) {
                appearance = new PerInstanceColorAppearance({
                    flat : true
                });
                this.appearance = appearance;
            }

            //>>includeStart('debug', pragmas.debug);
            if (!hasPerColorAttribute && appearance instanceof PerInstanceColorAppearance) {
                throw new DeveloperError('PerInstanceColorAppearance requires color GeometryInstanceAttributes on all GeometryInstances');
            }
            if (defined(appearance.material) && !hasSphericalExtentsAttribute && !hasPlanarExtentsAttributes) {
                throw new DeveloperError('Materials on ClassificationPrimitives are not supported except via GroundPrimitives');
            }
            //>>includeEnd('debug');

            this._usePickOffsets = !hasSphericalExtentsAttribute && !hasPlanarExtentsAttributes;
            this._hasSphericalExtentsAttribute = hasSphericalExtentsAttribute;
            this._hasPlanarExtentsAttributes = hasPlanarExtentsAttributes;
            this._hasPerColorAttribute = hasPerColorAttribute;

            var geometryInstances = new Array(length);
            for (i = 0; i < length; ++i) {
                instance = instances[i];
                geometryInstances[i] = new GeometryInstance({
                    geometry : instance.geometry,
                    attributes : instance.attributes,
                    modelMatrix : instance.modelMatrix,
                    id : instance.id,
                    pickPrimitive : defaultValue(this._pickPrimitive, that)
                });
            }

            primitiveOptions.appearance = appearance;
            primitiveOptions.geometryInstances = geometryInstances;

            if (defined(this._createBoundingVolumeFunction)) {
                primitiveOptions._createBoundingVolumeFunction = function(frameState, geometry) {
                    that._createBoundingVolumeFunction(frameState, geometry);
                };
            }

            primitiveOptions._createRenderStatesFunction = function(primitive, context, appearance, twoPasses) {
                createRenderStates(that, context);
            };
            primitiveOptions._createShaderProgramFunction = function(primitive, frameState, appearance) {
                createShaderProgram(that, frameState);
            };
            primitiveOptions._createCommandsFunction = function(primitive, appearance, material, translucent, twoPasses, colorCommands, pickCommands) {
                createCommands(that, undefined, undefined, true, false, colorCommands, pickCommands);
            };

            if (defined(this._updateAndQueueCommandsFunction)) {
                primitiveOptions._updateAndQueueCommandsFunction = function(primitive, frameState, colorCommands, pickCommands, modelMatrix, cull, debugShowBoundingVolume, twoPasses) {
                    that._updateAndQueueCommandsFunction(primitive, frameState, colorCommands, pickCommands, modelMatrix, cull, debugShowBoundingVolume, twoPasses);
                };
            } else {
                primitiveOptions._updateAndQueueCommandsFunction = function(primitive, frameState, colorCommands, pickCommands, modelMatrix, cull, debugShowBoundingVolume, twoPasses) {
                    updateAndQueueCommands(that, frameState, colorCommands, pickCommands, modelMatrix, cull, debugShowBoundingVolume, twoPasses);
                };
            }

            this._primitive = new Primitive(primitiveOptions);
            this._primitive.readyPromise.then(function(primitive) {
                that._ready = true;

                if (that.releaseGeometryInstances) {
                    that.geometryInstances = undefined;
                }

                var error = primitive._error;
                if (!defined(error)) {
                    that._readyPromise.resolve(that);
                } else {
                    that._readyPromise.reject(error);
                }
            });
        }

        if (this.debugShowShadowVolume && !this._debugShowShadowVolume && this._ready) {
            this._debugShowShadowVolume = true;
            this._rsStencilPreloadPass = RenderState.fromCache(getStencilPreloadRenderState(false, false));
            this._rsStencilPreloadPass3DTiles = RenderState.fromCache(getStencilPreloadRenderState(false, true));
            this._rsStencilDepthPass = RenderState.fromCache(getStencilDepthRenderState(false, false));
            this._rsStencilDepthPass3DTiles = RenderState.fromCache(getStencilDepthRenderState(false, true));
            this._rsColorPass = RenderState.fromCache(getColorRenderState(false));
        } else if (!this.debugShowShadowVolume && this._debugShowShadowVolume) {
            this._debugShowShadowVolume = false;
            this._rsStencilPreloadPass = RenderState.fromCache(getStencilPreloadRenderState(true, false));
            this._rsStencilPreloadPass3DTiles = RenderState.fromCache(getStencilPreloadRenderState(true, true));
            this._rsStencilDepthPass = RenderState.fromCache(getStencilDepthRenderState(true, false));
            this._rsStencilDepthPass3DTiles = RenderState.fromCache(getStencilDepthRenderState(true, true));
            this._rsColorPass = RenderState.fromCache(getColorRenderState(true));
        }
        // Update primitive appearance
        if (this._primitive.appearance !== appearance) {
            //>>includeStart('debug', pragmas.debug);
            // Check if the appearance is supported by the geometry attributes
            if (!this._hasSphericalExtentsAttribute && !this._hasPlanarExtentsAttributes && defined(appearance.material)) {
                throw new DeveloperError('Materials on ClassificationPrimitives are not supported except via GroundPrimitive');
            }
            if (!this._hasPerColorAttribute && appearance instanceof PerInstanceColorAppearance) {
                throw new DeveloperError('PerInstanceColorAppearance requires color GeometryInstanceAttribute');
            }
            //>>includeEnd('debug');
            this._primitive.appearance = appearance;
        }

        this._primitive.show = this.show;
        this._primitive.debugShowBoundingVolume = this.debugShowBoundingVolume;
        this._primitive.update(frameState);
    };

    /**
     * Returns the modifiable per-instance attributes for a {@link GeometryInstance}.
     *
     * @param {*} id The id of the {@link GeometryInstance}.
     * @returns {Object} The typed array in the attribute's format or undefined if the is no instance with id.
     *
     * @exception {DeveloperError} must call update before calling getGeometryInstanceAttributes.
     *
     * @example
     * var attributes = primitive.getGeometryInstanceAttributes('an id');
     * attributes.color = Cesium.ColorGeometryInstanceAttribute.toValue(Cesium.Color.AQUA);
     * attributes.show = Cesium.ShowGeometryInstanceAttribute.toValue(true);
     */
    ClassificationPrimitive.prototype.getGeometryInstanceAttributes = function(id) {
        //>>includeStart('debug', pragmas.debug);
        if (!defined(this._primitive)) {
            throw new DeveloperError('must call update before calling getGeometryInstanceAttributes');
        }
        //>>includeEnd('debug');
        return this._primitive.getGeometryInstanceAttributes(id);
    };

    /**
     * Returns true if this object was destroyed; otherwise, false.
     * <p>
     * If this object was destroyed, it should not be used; calling any function other than
     * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
     * </p>
     *
     * @returns {Boolean} <code>true</code> if this object was destroyed; otherwise, <code>false</code>.
     *
     * @see ClassificationPrimitive#destroy
     */
    ClassificationPrimitive.prototype.isDestroyed = function() {
        return false;
    };

    /**
     * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
     * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
     * <p>
     * Once an object is destroyed, it should not be used; calling any function other than
     * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
     * assign the return value (<code>undefined</code>) to the object as done in the example.
     * </p>
     *
     * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
     *
     * @example
     * e = e && e.destroy();
     *
     * @see ClassificationPrimitive#isDestroyed
     */
    ClassificationPrimitive.prototype.destroy = function() {
        this._primitive = this._primitive && this._primitive.destroy();
        this._sp = this._sp && this._sp.destroy();
        this._spPick = this._spPick && this._spPick.destroy();
        this._spColor = this._spColor && this._spColor.destroy();

        // Derived programs, destroyed above if they existed.
        this._spPick2D = undefined;
        this._spColor2D = undefined;
        return destroyObject(this);
    };

    return ClassificationPrimitive;
});