ZhongMianAdmin/__test__/bim/js/io/GLTFExporter.js

import {
    BufferAttribute,
    ClampToEdgeWrapping,
    DoubleSide,
    InterpolateDiscrete,
    InterpolateLinear,
    LinearFilter,
    LinearMipmapLinearFilter,
    LinearMipmapNearestFilter,
    MathUtils,
    Matrix4,
    MirroredRepeatWrapping,
    NearestFilter,
    NearestMipmapLinearFilter,
    NearestMipmapNearestFilter,
    Object3D, // bimrocket
    Group, // bimrocket
    PropertyBinding,
    RGBAFormat,
    RepeatWrapping,
    Scene,
    Source,
    Vector3
} from '../lib/three.module.js'

class GLTFExporter {
    constructor() {
        this.pluginCallbacks = []

        this.register(function(writer) {
            return new GLTFLightExtension(writer)
        })

        this.register(function(writer) {
            return new GLTFMaterialsUnlitExtension(writer)
        })

        this.register(function(writer) {
            return new GLTFMaterialsPBRSpecularGlossiness(writer)
        })

        this.register(function(writer) {
            return new GLTFMaterialsTransmissionExtension(writer)
        })

        this.register(function(writer) {
            return new GLTFMaterialsVolumeExtension(writer)
        })

        this.register(function(writer) {
            return new GLTFMaterialsClearcoatExtension(writer)
        })
    }

    register(callback) {
        if (this.pluginCallbacks.indexOf(callback) === -1) {
            this.pluginCallbacks.push(callback)
        }

        return this
    }

    unregister(callback) {
        if (this.pluginCallbacks.indexOf(callback) !== -1) {
            this.pluginCallbacks.splice(this.pluginCallbacks.indexOf(callback), 1)
        }

        return this
    }

    /**
     * Parse scenes and generate GLTF output
     * @param  {Scene or [THREE.Scenes]} input   Scene or Array of THREE.Scenes
     * @param  {Function} onDone  Callback on completed
     * @param  {Function} onError  Callback on errors
     * @param  {Object} options options
     */
    parse(input, onDone, onError, options) {
        if (typeof onError === 'object') {
            console.warn('THREE.GLTFExporter: parse() expects options as the fourth argument now.')

            options = onError
        }

        const writer = new GLTFWriter()
        const plugins = []

        for (let i = 0, il = this.pluginCallbacks.length; i < il; i++) {
            plugins.push(this.pluginCallbacks[i](writer))
        }

        writer.setPlugins(plugins)
        writer.write(input, onDone, options).catch(onError)
    }

    parseAsync(input, options) {
        const scope = this

        return new Promise(function(resolve, reject) {
            scope.parse(input, resolve, reject, options)
        })
    }
}

//------------------------------------------------------------------------------
// Constants
//------------------------------------------------------------------------------

const WEBGL_CONSTANTS = {
    POINTS: 0x0000,
    LINES: 0x0001,
    LINE_LOOP: 0x0002,
    LINE_STRIP: 0x0003,
    TRIANGLES: 0x0004,
    TRIANGLE_STRIP: 0x0005,
    TRIANGLE_FAN: 0x0006,

    UNSIGNED_BYTE: 0x1401,
    UNSIGNED_SHORT: 0x1403,
    FLOAT: 0x1406,
    UNSIGNED_INT: 0x1405,
    ARRAY_BUFFER: 0x8892,
    ELEMENT_ARRAY_BUFFER: 0x8893,

    NEAREST: 0x2600,
    LINEAR: 0x2601,
    NEAREST_MIPMAP_NEAREST: 0x2700,
    LINEAR_MIPMAP_NEAREST: 0x2701,
    NEAREST_MIPMAP_LINEAR: 0x2702,
    LINEAR_MIPMAP_LINEAR: 0x2703,

    CLAMP_TO_EDGE: 33071,
    MIRRORED_REPEAT: 33648,
    REPEAT: 10497
}

const THREE_TO_WEBGL = {}

THREE_TO_WEBGL[NearestFilter] = WEBGL_CONSTANTS.NEAREST
THREE_TO_WEBGL[NearestMipmapNearestFilter] = WEBGL_CONSTANTS.NEAREST_MIPMAP_NEAREST
THREE_TO_WEBGL[NearestMipmapLinearFilter] = WEBGL_CONSTANTS.NEAREST_MIPMAP_LINEAR
THREE_TO_WEBGL[LinearFilter] = WEBGL_CONSTANTS.LINEAR
THREE_TO_WEBGL[LinearMipmapNearestFilter] = WEBGL_CONSTANTS.LINEAR_MIPMAP_NEAREST
THREE_TO_WEBGL[LinearMipmapLinearFilter] = WEBGL_CONSTANTS.LINEAR_MIPMAP_LINEAR

THREE_TO_WEBGL[ClampToEdgeWrapping] = WEBGL_CONSTANTS.CLAMP_TO_EDGE
THREE_TO_WEBGL[RepeatWrapping] = WEBGL_CONSTANTS.REPEAT
THREE_TO_WEBGL[MirroredRepeatWrapping] = WEBGL_CONSTANTS.MIRRORED_REPEAT

const PATH_PROPERTIES = {
    scale: 'scale',
    position: 'translation',
    quaternion: 'rotation',
    morphTargetInfluences: 'weights'
}

// GLB constants
// https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#glb-file-format-specification

const GLB_HEADER_BYTES = 12
const GLB_HEADER_MAGIC = 0x46546c67
const GLB_VERSION = 2

const GLB_CHUNK_PREFIX_BYTES = 8
const GLB_CHUNK_TYPE_JSON = 0x4e4f534a
const GLB_CHUNK_TYPE_BIN = 0x004e4942

//------------------------------------------------------------------------------
// Utility functions
//------------------------------------------------------------------------------

/**
 * Compare two arrays
 * @param  {Array} array1 Array 1 to compare
 * @param  {Array} array2 Array 2 to compare
 * @return {Boolean}        Returns true if both arrays are equal
 */
function equalArray(array1, array2) {
    return (
        array1.length === array2.length &&
        array1.every(function(element, index) {
            return element === array2[index]
        })
    )
}

/**
 * Converts a string to an ArrayBuffer.
 * @param  {string} text
 * @return {ArrayBuffer}
 */
function stringToArrayBuffer(text) {
    return new TextEncoder().encode(text).buffer
}

/**
 * Is identity matrix
 *
 * @param {Matrix4} matrix
 * @returns {Boolean} Returns true, if parameter is identity matrix
 */
function isIdentityMatrix(matrix) {
    return equalArray(matrix.elements, [1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1])
}

/**
 * Get the min and max vectors from the given attribute
 * @param  {BufferAttribute} attribute Attribute to find the min/max in range from start to start + count
 * @param  {Integer} start
 * @param  {Integer} count
 * @return {Object} Object containing the `min` and `max` values (As an array of attribute.itemSize components)
 */
function getMinMax(attribute, start, count) {
    const output = {
        min: new Array(attribute.itemSize).fill(Number.POSITIVE_INFINITY),
        max: new Array(attribute.itemSize).fill(Number.NEGATIVE_INFINITY)
    }

    for (let i = start; i < start + count; i++) {
        for (let a = 0; a < attribute.itemSize; a++) {
            let value

            if (attribute.itemSize > 4) {
                // no support for interleaved data for itemSize > 4

                value = attribute.array[i * attribute.itemSize + a]
            } else {
                if (a === 0) value = attribute.getX(i)
                else if (a === 1) value = attribute.getY(i)
                else if (a === 2) value = attribute.getZ(i)
                else if (a === 3) value = attribute.getW(i)
            }

            output.min[a] = Math.min(output.min[a], value)
            output.max[a] = Math.max(output.max[a], value)
        }
    }

    return output
}

/**
 * Get the required size + padding for a buffer, rounded to the next 4-byte boundary.
 * https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#data-alignment
 *
 * @param {Integer} bufferSize The size the original buffer.
 * @returns {Integer} new buffer size with required padding.
 *
 */
function getPaddedBufferSize(bufferSize) {
    return Math.ceil(bufferSize / 4) * 4
}

/**
 * Returns a buffer aligned to 4-byte boundary.
 *
 * @param {ArrayBuffer} arrayBuffer Buffer to pad
 * @param {Integer} paddingByte (Optional)
 * @returns {ArrayBuffer} The same buffer if it's already aligned to 4-byte boundary or a new buffer
 */
function getPaddedArrayBuffer(arrayBuffer, paddingByte = 0) {
    const paddedLength = getPaddedBufferSize(arrayBuffer.byteLength)

    if (paddedLength !== arrayBuffer.byteLength) {
        const array = new Uint8Array(paddedLength)
        array.set(new Uint8Array(arrayBuffer))

        if (paddingByte !== 0) {
            for (let i = arrayBuffer.byteLength; i < paddedLength; i++) {
                array[i] = paddingByte
            }
        }

        return array.buffer
    }

    return arrayBuffer
}

let cachedCanvas = null

function getCanvas() {
    if (cachedCanvas) {
        return cachedCanvas
    }

    if (typeof OffscreenCanvas !== 'undefined') {
        cachedCanvas = new OffscreenCanvas(1, 1)
    } else {
        cachedCanvas = document.createElement('canvas')
    }

    return cachedCanvas
}

/**
 * Writer
 */
class GLTFWriter {
    constructor() {
        this.plugins = []

        this.options = {}
        this.pending = []
        this.buffers = []

        this.byteOffset = 0
        this.buffers = []
        this.nodeMap = new Map()
        this.skins = []
        this.extensionsUsed = {}

        this.uids = new Map()
        this.uid = 0

        this.json = {
            asset: {
                version: '2.0',
                generator: 'THREE.GLTFExporter'
            }
        }

        this.cache = {
            meshes: new Map(),
            attributes: new Map(),
            attributesNormalized: new Map(),
            materials: new Map(),
            textures: new Map(),
            images: new Map()
        }
    }

    setPlugins(plugins) {
        this.plugins = plugins
    }

    /**
     * Parse scenes and generate GLTF output
     * @param  {Scene or [THREE.Scenes]} input   Scene or Array of THREE.Scenes
     * @param  {Function} onDone  Callback on completed
     * @param  {Object} options options
     */
    async write(input, onDone, options) {
        this.options = Object.assign(
            {},
            {
                // default options
                binary: false,
                trs: false,
                onlyVisible: true,
                truncateDrawRange: true,
                embedImages: true,
                maxTextureSize: Infinity,
                animations: [],
                includeCustomExtensions: false
            },
            options
        )

        if (this.options.animations.length > 0) {
            // Only TRS properties, and not matrices, may be targeted by animation.
            this.options.trs = true
        }

        this.processInput(input)

        await Promise.all(this.pending)

        const writer = this
        const buffers = writer.buffers
        const json = writer.json
        options = writer.options
        const extensionsUsed = writer.extensionsUsed

        // Merge buffers.
        const blob = new Blob(buffers, { type: 'application/octet-stream' })

        // Declare extensions.
        const extensionsUsedList = Object.keys(extensionsUsed)

        if (extensionsUsedList.length > 0) json.extensionsUsed = extensionsUsedList

        // Update bytelength of the single buffer.
        if (json.buffers && json.buffers.length > 0) json.buffers[0].byteLength = blob.size

        if (options.binary === true) {
            // https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#glb-file-format-specification

            const reader = new FileReader()
            reader.readAsArrayBuffer(blob)
            reader.onloadend = function() {
                // Binary chunk.
                const binaryChunk = getPaddedArrayBuffer(reader.result)
                const binaryChunkPrefix = new DataView(new ArrayBuffer(GLB_CHUNK_PREFIX_BYTES))
                binaryChunkPrefix.setUint32(0, binaryChunk.byteLength, true)
                binaryChunkPrefix.setUint32(4, GLB_CHUNK_TYPE_BIN, true)

                // JSON chunk.
                const jsonChunk = getPaddedArrayBuffer(stringToArrayBuffer(JSON.stringify(json)), 0x20)
                const jsonChunkPrefix = new DataView(new ArrayBuffer(GLB_CHUNK_PREFIX_BYTES))
                jsonChunkPrefix.setUint32(0, jsonChunk.byteLength, true)
                jsonChunkPrefix.setUint32(4, GLB_CHUNK_TYPE_JSON, true)

                // GLB header.
                const header = new ArrayBuffer(GLB_HEADER_BYTES)
                const headerView = new DataView(header)
                headerView.setUint32(0, GLB_HEADER_MAGIC, true)
                headerView.setUint32(4, GLB_VERSION, true)
                const totalByteLength = GLB_HEADER_BYTES + jsonChunkPrefix.byteLength + jsonChunk.byteLength + binaryChunkPrefix.byteLength + binaryChunk.byteLength
                headerView.setUint32(8, totalByteLength, true)

                const glbBlob = new Blob([header, jsonChunkPrefix, jsonChunk, binaryChunkPrefix, binaryChunk], { type: 'application/octet-stream' })

                const glbReader = new FileReader()
                glbReader.readAsArrayBuffer(glbBlob)
                glbReader.onloadend = function() {
                    onDone(glbReader.result)
                }
            }
        } else {
            if (json.buffers && json.buffers.length > 0) {
                const reader = new FileReader()
                reader.readAsDataURL(blob)
                reader.onloadend = function() {
                    const base64data = reader.result
                    json.buffers[0].uri = base64data
                    onDone(json)
                }
            } else {
                onDone(json)
            }
        }
    }

    /**
     * Serializes a userData.
     *
     * @param {THREE.Object3D|THREE.Material} object
     * @param {Object} objectDef
     */
    serializeUserData(object, objectDef) {
        if (Object.keys(object.userData).length === 0) return

        const options = this.options
        const extensionsUsed = this.extensionsUsed

        try {
            const json = JSON.parse(JSON.stringify(object.userData))

            if (options.includeCustomExtensions && json.gltfExtensions) {
                if (objectDef.extensions === undefined) objectDef.extensions = {}

                for (const extensionName in json.gltfExtensions) {
                    objectDef.extensions[extensionName] = json.gltfExtensions[extensionName]
                    extensionsUsed[extensionName] = true
                }

                delete json.gltfExtensions
            }

            if (Object.keys(json).length > 0) objectDef.extras = json
        } catch (error) {
            console.warn("THREE.GLTFExporter: userData of '" + object.name + "' " + "won't be serialized because of JSON.stringify error - " + error.message)
        }
    }

    /**
     * Assign and return a temporal unique id for an object
     * especially which doesn't have .uuid
     * @param  {Object} object
     * @return {Integer}
     */
    getUID(object) {
        if (!this.uids.has(object)) this.uids.set(object, this.uid++)

        return this.uids.get(object)
    }

    /**
     * Checks if normal attribute values are normalized.
     *
     * @param {BufferAttribute} normal
     * @returns {Boolean}
     */
    isNormalizedNormalAttribute(normal) {
        const cache = this.cache

        if (cache.attributesNormalized.has(normal)) return false

        const v = new Vector3()

        for (let i = 0, il = normal.count; i < il; i++) {
            // 0.0005 is from glTF-validator
            if (Math.abs(v.fromBufferAttribute(normal, i).length() - 1.0) > 0.0005) return false
        }

        return true
    }

    /**
     * Creates normalized normal buffer attribute.
     *
     * @param {BufferAttribute} normal
     * @returns {BufferAttribute}
     *
     */
    createNormalizedNormalAttribute(normal) {
        const cache = this.cache

        if (cache.attributesNormalized.has(normal)) return cache.attributesNormalized.get(normal)

        const attribute = normal.clone()
        const v = new Vector3()

        for (let i = 0, il = attribute.count; i < il; i++) {
            v.fromBufferAttribute(attribute, i)

            if (v.x === 0 && v.y === 0 && v.z === 0) {
                // if values can't be normalized set (1, 0, 0)
                v.setX(1.0)
            } else {
                v.normalize()
            }

            attribute.setXYZ(i, v.x, v.y, v.z)
        }

        cache.attributesNormalized.set(normal, attribute)

        return attribute
    }

    /**
     * Applies a texture transform, if present, to the map definition. Requires
     * the KHR_texture_transform extension.
     *
     * @param {Object} mapDef
     * @param {THREE.Texture} texture
     */
    applyTextureTransform(mapDef, texture) {
        let didTransform = false
        const transformDef = {}

        if (texture.offset.x !== 0 || texture.offset.y !== 0) {
            transformDef.offset = texture.offset.toArray()
            didTransform = true
        }

        if (texture.rotation !== 0) {
            transformDef.rotation = texture.rotation
            didTransform = true
        }

        if (texture.repeat.x !== 1 || texture.repeat.y !== 1) {
            transformDef.scale = texture.repeat.toArray()
            didTransform = true
        }

        if (didTransform) {
            mapDef.extensions = mapDef.extensions || {}
            mapDef.extensions['KHR_texture_transform'] = transformDef
            this.extensionsUsed['KHR_texture_transform'] = true
        }
    }

    buildMetalRoughTexture(metalnessMap, roughnessMap) {
        if (metalnessMap === roughnessMap) return metalnessMap

        console.warn('THREE.GLTFExporter: Merged metalnessMap and roughnessMap textures.')

        // bimrocket: replace ?. operator
        const metalness = metalnessMap ? metalnessMap.image : undefined
        const roughness = roughnessMap ? roughnessMap.image : undefined

        const width = Math.max(metalness ? metalness.width || 0 : undefined, roughness ? roughness.width || 0 : undefined)
        const height = Math.max(metalness ? metalness.height || 0 : undefined, roughness ? roughness.height || 0 : undefined)

        const canvas = getCanvas()
        canvas.width = width
        canvas.height = height

        const context = canvas.getContext('2d')
        context.fillStyle = '#00ffff'
        context.fillRect(0, 0, width, height)

        const composite = context.getImageData(0, 0, width, height)

        if (metalness) {
            context.drawImage(metalness, 0, 0, width, height)

            const data = context.getImageData(0, 0, width, height).data

            for (let i = 2; i < data.length; i += 4) {
                composite.data[i] = data[i]
            }
        }

        if (roughness) {
            context.drawImage(roughness, 0, 0, width, height)

            const data = context.getImageData(0, 0, width, height).data

            for (let i = 1; i < data.length; i += 4) {
                composite.data[i] = data[i]
            }
        }

        context.putImageData(composite, 0, 0)

        //

        const reference = metalnessMap || roughnessMap

        const texture = reference.clone()

        texture.source = new Source(canvas)

        return texture
    }

    /**
     * Process a buffer to append to the default one.
     * @param  {ArrayBuffer} buffer
     * @return {Integer}
     */
    processBuffer(buffer) {
        const json = this.json
        const buffers = this.buffers

        if (!json.buffers) json.buffers = [{ byteLength: 0 }]

        // All buffers are merged before export.
        buffers.push(buffer)

        return 0
    }

    /**
     * Process and generate a BufferView
     * @param  {BufferAttribute} attribute
     * @param  {number} componentType
     * @param  {number} start
     * @param  {number} count
     * @param  {number} target (Optional) Target usage of the BufferView
     * @return {Object}
     */
    processBufferView(attribute, componentType, start, count, target) {
        const json = this.json

        if (!json.bufferViews) json.bufferViews = []

        // Create a new dataview and dump the attribute's array into it

        let componentSize

        if (componentType === WEBGL_CONSTANTS.UNSIGNED_BYTE) {
            componentSize = 1
        } else if (componentType === WEBGL_CONSTANTS.UNSIGNED_SHORT) {
            componentSize = 2
        } else {
            componentSize = 4
        }

        const byteLength = getPaddedBufferSize(count * attribute.itemSize * componentSize)
        const dataView = new DataView(new ArrayBuffer(byteLength))
        let offset = 0

        for (let i = start; i < start + count; i++) {
            for (let a = 0; a < attribute.itemSize; a++) {
                let value

                if (attribute.itemSize > 4) {
                    // no support for interleaved data for itemSize > 4

                    value = attribute.array[i * attribute.itemSize + a]
                } else {
                    if (a === 0) value = attribute.getX(i)
                    else if (a === 1) value = attribute.getY(i)
                    else if (a === 2) value = attribute.getZ(i)
                    else if (a === 3) value = attribute.getW(i)
                }

                if (componentType === WEBGL_CONSTANTS.FLOAT) {
                    dataView.setFloat32(offset, value, true)
                } else if (componentType === WEBGL_CONSTANTS.UNSIGNED_INT) {
                    dataView.setUint32(offset, value, true)
                } else if (componentType === WEBGL_CONSTANTS.UNSIGNED_SHORT) {
                    dataView.setUint16(offset, value, true)
                } else if (componentType === WEBGL_CONSTANTS.UNSIGNED_BYTE) {
                    dataView.setUint8(offset, value)
                }

                offset += componentSize
            }
        }

        const bufferViewDef = {
            buffer: this.processBuffer(dataView.buffer),
            byteOffset: this.byteOffset,
            byteLength: byteLength
        }

        if (target !== undefined) bufferViewDef.target = target

        if (target === WEBGL_CONSTANTS.ARRAY_BUFFER) {
            // Only define byteStride for vertex attributes.
            bufferViewDef.byteStride = attribute.itemSize * componentSize
        }

        this.byteOffset += byteLength

        json.bufferViews.push(bufferViewDef)

        // @TODO Merge bufferViews where possible.
        const output = {
            id: json.bufferViews.length - 1,
            byteLength: 0
        }

        return output
    }

    /**
     * Process and generate a BufferView from an image Blob.
     * @param {Blob} blob
     * @return {Promise<Integer>}
     */
    processBufferViewImage(blob) {
        const writer = this
        const json = writer.json

        if (!json.bufferViews) json.bufferViews = []

        return new Promise(function(resolve) {
            const reader = new FileReader()
            reader.readAsArrayBuffer(blob)
            reader.onloadend = function() {
                const buffer = getPaddedArrayBuffer(reader.result)

                const bufferViewDef = {
                    buffer: writer.processBuffer(buffer),
                    byteOffset: writer.byteOffset,
                    byteLength: buffer.byteLength
                }

                writer.byteOffset += buffer.byteLength
                resolve(json.bufferViews.push(bufferViewDef) - 1)
            }
        })
    }

    /**
     * Process attribute to generate an accessor
     * @param  {BufferAttribute} attribute Attribute to process
     * @param  {THREE.BufferGeometry} geometry (Optional) Geometry used for truncated draw range
     * @param  {Integer} start (Optional)
     * @param  {Integer} count (Optional)
     * @return {Integer|null} Index of the processed accessor on the "accessors" array
     */
    processAccessor(attribute, geometry, start, count) {
        const options = this.options
        const json = this.json

        const types = {
            1: 'SCALAR',
            2: 'VEC2',
            3: 'VEC3',
            4: 'VEC4',
            16: 'MAT4'
        }

        let componentType

        // Detect the component type of the attribute array (float, uint or ushort)
        if (attribute.array.constructor === Float32Array) {
            componentType = WEBGL_CONSTANTS.FLOAT
        } else if (attribute.array.constructor === Uint32Array) {
            componentType = WEBGL_CONSTANTS.UNSIGNED_INT
        } else if (attribute.array.constructor === Uint16Array) {
            componentType = WEBGL_CONSTANTS.UNSIGNED_SHORT
        } else if (attribute.array.constructor === Uint8Array) {
            componentType = WEBGL_CONSTANTS.UNSIGNED_BYTE
        } else {
            throw new Error('THREE.GLTFExporter: Unsupported bufferAttribute component type.')
        }

        if (start === undefined) start = 0
        if (count === undefined) count = attribute.count

        // @TODO Indexed buffer geometry with drawRange not supported yet
        if (options.truncateDrawRange && geometry !== undefined && geometry.index === null) {
            const end = start + count
            const end2 = geometry.drawRange.count === Infinity ? attribute.count : geometry.drawRange.start + geometry.drawRange.count

            start = Math.max(start, geometry.drawRange.start)
            count = Math.min(end, end2) - start

            if (count < 0) count = 0
        }

        // Skip creating an accessor if the attribute doesn't have data to export
        if (count === 0) return null

        const minMax = getMinMax(attribute, start, count)
        let bufferViewTarget

        // If geometry isn't provided, don't infer the target usage of the bufferView. For
        // animation samplers, target must not be set.
        if (geometry !== undefined) {
            bufferViewTarget = attribute === geometry.index ? WEBGL_CONSTANTS.ELEMENT_ARRAY_BUFFER : WEBGL_CONSTANTS.ARRAY_BUFFER
        }

        const bufferView = this.processBufferView(attribute, componentType, start, count, bufferViewTarget)

        const accessorDef = {
            bufferView: bufferView.id,
            byteOffset: bufferView.byteOffset,
            componentType: componentType,
            count: count,
            max: minMax.max,
            min: minMax.min,
            type: types[attribute.itemSize]
        }

        if (attribute.normalized === true) accessorDef.normalized = true
        if (!json.accessors) json.accessors = []

        return json.accessors.push(accessorDef) - 1
    }

    /**
     * Process image
     * @param  {Image} image to process
     * @param  {Integer} format of the image (RGBAFormat)
     * @param  {Boolean} flipY before writing out the image
     * @param  {String} mimeType export format
     * @return {Integer}     Index of the processed texture in the "images" array
     */
    processImage(image, format, flipY, mimeType = 'image/png') {
        const writer = this
        const cache = writer.cache
        const json = writer.json
        const options = writer.options
        const pending = writer.pending

        if (!cache.images.has(image)) cache.images.set(image, {})

        const cachedImages = cache.images.get(image)

        const key = mimeType + ':flipY/' + flipY.toString()

        if (cachedImages[key] !== undefined) return cachedImages[key]

        if (!json.images) json.images = []

        const imageDef = { mimeType: mimeType }

        if (options.embedImages) {
            const canvas = getCanvas()

            canvas.width = Math.min(image.width, options.maxTextureSize)
            canvas.height = Math.min(image.height, options.maxTextureSize)

            const ctx = canvas.getContext('2d')

            if (flipY === true) {
                ctx.translate(0, canvas.height)
                ctx.scale(1, -1)
            }

            if (image.data !== undefined) {
                // THREE.DataTexture

                if (format !== RGBAFormat) {
                    console.error('GLTFExporter: Only RGBAFormat is supported.')
                }

                if (image.width > options.maxTextureSize || image.height > options.maxTextureSize) {
                    console.warn('GLTFExporter: Image size is bigger than maxTextureSize', image)
                }

                const data = new Uint8ClampedArray(image.height * image.width * 4)

                for (let i = 0; i < data.length; i += 4) {
                    data[i + 0] = image.data[i + 0]
                    data[i + 1] = image.data[i + 1]
                    data[i + 2] = image.data[i + 2]
                    data[i + 3] = image.data[i + 3]
                }

                ctx.putImageData(new ImageData(data, image.width, image.height), 0, 0)
            } else {
                ctx.drawImage(image, 0, 0, canvas.width, canvas.height)
            }

            if (options.binary === true) {
                let toBlobPromise

                if (canvas.toBlob !== undefined) {
                    toBlobPromise = new Promise(resolve => canvas.toBlob(resolve, mimeType))
                } else {
                    toBlobPromise = canvas.convertToBlob({ type: mimeType })
                }

                pending.push(
                    toBlobPromise.then(blob =>
                        writer.processBufferViewImage(blob).then(bufferViewIndex => {
                            imageDef.bufferView = bufferViewIndex
                        })
                    )
                )
            } else {
                imageDef.uri = canvas.toDataURL(mimeType)
            }
        } else {
            imageDef.uri = image.src
        }

        const index = json.images.push(imageDef) - 1
        cachedImages[key] = index
        return index
    }

    /**
     * Process sampler
     * @param  {Texture} map Texture to process
     * @return {Integer}     Index of the processed texture in the "samplers" array
     */
    processSampler(map) {
        const json = this.json

        if (!json.samplers) json.samplers = []

        const samplerDef = {
            magFilter: THREE_TO_WEBGL[map.magFilter],
            minFilter: THREE_TO_WEBGL[map.minFilter],
            wrapS: THREE_TO_WEBGL[map.wrapS],
            wrapT: THREE_TO_WEBGL[map.wrapT]
        }

        return json.samplers.push(samplerDef) - 1
    }

    /**
     * Process texture
     * @param  {Texture} map Map to process
     * @return {Integer} Index of the processed texture in the "textures" array
     */
    processTexture(map) {
        const cache = this.cache
        const json = this.json

        if (cache.textures.has(map)) return cache.textures.get(map)

        if (!json.textures) json.textures = []

        let mimeType = map.userData.mimeType

        if (mimeType === 'image/webp') mimeType = 'image/png'

        const textureDef = {
            sampler: this.processSampler(map),
            source: this.processImage(map.image, map.format, map.flipY, mimeType)
        }

        if (map.name) textureDef.name = map.name

        this._invokeAll(function(ext) {
            ext.writeTexture && ext.writeTexture(map, textureDef)
        })

        const index = json.textures.push(textureDef) - 1
        cache.textures.set(map, index)
        return index
    }

    /**
     * Process material
     * @param  {THREE.Material} material Material to process
     * @return {Integer|null} Index of the processed material in the "materials" array
     */
    processMaterial(material) {
        const cache = this.cache
        const json = this.json

        if (cache.materials.has(material)) return cache.materials.get(material)

        if (material.isShaderMaterial) {
            console.warn('GLTFExporter: THREE.ShaderMaterial not supported.')
            return null
        }

        if (!json.materials) json.materials = []

        // @QUESTION Should we avoid including any attribute that has the default value?
        const materialDef = { pbrMetallicRoughness: {} }

        if (material.isMeshStandardMaterial !== true && material.isMeshBasicMaterial !== true) {
            console.warn('GLTFExporter: Use MeshStandardMaterial or MeshBasicMaterial for best results.')
        }

        // pbrMetallicRoughness.baseColorFactor
        const color = material.color.toArray().concat([material.opacity])

        if (!equalArray(color, [1, 1, 1, 1])) {
            materialDef.pbrMetallicRoughness.baseColorFactor = color
        }

        if (material.isMeshStandardMaterial) {
            materialDef.pbrMetallicRoughness.metallicFactor = material.metalness
            materialDef.pbrMetallicRoughness.roughnessFactor = material.roughness
        } else {
            materialDef.pbrMetallicRoughness.metallicFactor = 0.5
            materialDef.pbrMetallicRoughness.roughnessFactor = 0.5
        }

        // pbrMetallicRoughness.metallicRoughnessTexture
        if (material.metalnessMap || material.roughnessMap) {
            const metalRoughTexture = this.buildMetalRoughTexture(material.metalnessMap, material.roughnessMap)

            const metalRoughMapDef = { index: this.processTexture(metalRoughTexture) }
            this.applyTextureTransform(metalRoughMapDef, metalRoughTexture)
            materialDef.pbrMetallicRoughness.metallicRoughnessTexture = metalRoughMapDef
        }

        // pbrMetallicRoughness.baseColorTexture or pbrSpecularGlossiness diffuseTexture
        if (material.map) {
            const baseColorMapDef = { index: this.processTexture(material.map) }
            this.applyTextureTransform(baseColorMapDef, material.map)
            materialDef.pbrMetallicRoughness.baseColorTexture = baseColorMapDef
        }

        if (material.emissive) {
            // note: emissive components are limited to stay within the 0 - 1 range to accommodate glTF spec. see #21849 and #22000.
            const emissive = material.emissive.clone().multiplyScalar(material.emissiveIntensity)
            const maxEmissiveComponent = Math.max(emissive.r, emissive.g, emissive.b)

            if (maxEmissiveComponent > 1) {
                emissive.multiplyScalar(1 / maxEmissiveComponent)

                console.warn('THREE.GLTFExporter: Some emissive components exceed 1; emissive has been limited')
            }

            if (maxEmissiveComponent > 0) {
                materialDef.emissiveFactor = emissive.toArray()
            }

            // emissiveTexture
            if (material.emissiveMap) {
                const emissiveMapDef = { index: this.processTexture(material.emissiveMap) }
                this.applyTextureTransform(emissiveMapDef, material.emissiveMap)
                materialDef.emissiveTexture = emissiveMapDef
            }
        }

        // normalTexture
        if (material.normalMap) {
            const normalMapDef = { index: this.processTexture(material.normalMap) }

            if (material.normalScale && material.normalScale.x !== 1) {
                // glTF normal scale is univariate. Ignore `y`, which may be flipped.
                // Context: https://github.com/mrdoob/three.js/issues/11438#issuecomment-507003995
                normalMapDef.scale = material.normalScale.x
            }

            this.applyTextureTransform(normalMapDef, material.normalMap)
            materialDef.normalTexture = normalMapDef
        }

        // occlusionTexture
        if (material.aoMap) {
            const occlusionMapDef = {
                index: this.processTexture(material.aoMap),
                texCoord: 1
            }

            if (material.aoMapIntensity !== 1.0) {
                occlusionMapDef.strength = material.aoMapIntensity
            }

            this.applyTextureTransform(occlusionMapDef, material.aoMap)
            materialDef.occlusionTexture = occlusionMapDef
        }

        // alphaMode
        if (material.transparent) {
            materialDef.alphaMode = 'BLEND'
        } else {
            if (material.alphaTest > 0.0) {
                materialDef.alphaMode = 'MASK'
                materialDef.alphaCutoff = material.alphaTest
            }
        }

        // doubleSided
        if (material.side === DoubleSide) materialDef.doubleSided = true
        if (material.name !== '') materialDef.name = material.name

        this.serializeUserData(material, materialDef)

        this._invokeAll(function(ext) {
            ext.writeMaterial && ext.writeMaterial(material, materialDef)
        })

        const index = json.materials.push(materialDef) - 1
        cache.materials.set(material, index)
        return index
    }

    /**
     * Process mesh
     * @param  {THREE.Mesh} mesh Mesh to process
     * @return {Integer|null} Index of the processed mesh in the "meshes" array
     */
    processMesh(mesh) {
        const cache = this.cache
        const json = this.json

        const meshCacheKeyParts = [mesh.geometry.uuid]

        if (Array.isArray(mesh.material)) {
            for (let i = 0, l = mesh.material.length; i < l; i++) {
                meshCacheKeyParts.push(mesh.material[i].uuid)
            }
        } else {
            meshCacheKeyParts.push(mesh.material.uuid)
        }

        const meshCacheKey = meshCacheKeyParts.join(':')

        if (cache.meshes.has(meshCacheKey)) return cache.meshes.get(meshCacheKey)

        const geometry = mesh.geometry
        let mode

        // Use the correct mode
        if (mesh.isLineSegments) {
            mode = WEBGL_CONSTANTS.LINES
        } else if (mesh.isLineLoop) {
            mode = WEBGL_CONSTANTS.LINE_LOOP
        } else if (mesh.isLine) {
            mode = WEBGL_CONSTANTS.LINE_STRIP
        } else if (mesh.isPoints) {
            mode = WEBGL_CONSTANTS.POINTS
        } else {
            mode = mesh.material.wireframe ? WEBGL_CONSTANTS.LINES : WEBGL_CONSTANTS.TRIANGLES
        }

        if (geometry.isBufferGeometry !== true) {
            throw new Error('THREE.GLTFExporter: Geometry is not of type THREE.BufferGeometry.')
        }

        const meshDef = {}
        const attributes = {}
        const primitives = []
        const targets = []

        // Conversion between attributes names in threejs and gltf spec
        const nameConversion = {
            uv: 'TEXCOORD_0',
            uv2: 'TEXCOORD_1',
            color: 'COLOR_0',
            skinWeight: 'WEIGHTS_0',
            skinIndex: 'JOINTS_0'
        }

        const originalNormal = geometry.getAttribute('normal')

        if (originalNormal !== undefined && !this.isNormalizedNormalAttribute(originalNormal)) {
            console.warn('THREE.GLTFExporter: Creating normalized normal attribute from the non-normalized one.')

            geometry.setAttribute('normal', this.createNormalizedNormalAttribute(originalNormal))
        }

        // @QUESTION Detect if .vertexColors = true?
        // For every attribute create an accessor
        let modifiedAttribute = null

        for (let attributeName in geometry.attributes) {
            // Ignore morph target attributes, which are exported later.
            if (attributeName.slice(0, 5) === 'morph') continue

            const attribute = geometry.attributes[attributeName]
            attributeName = nameConversion[attributeName] || attributeName.toUpperCase()

            // Prefix all geometry attributes except the ones specifically
            // listed in the spec; non-spec attributes are considered custom.
            const validVertexAttributes = /^(POSITION|NORMAL|TANGENT|TEXCOORD_\d+|COLOR_\d+|JOINTS_\d+|WEIGHTS_\d+)$/

            if (!validVertexAttributes.test(attributeName)) attributeName = '_' + attributeName

            if (cache.attributes.has(this.getUID(attribute))) {
                attributes[attributeName] = cache.attributes.get(this.getUID(attribute))
                continue
            }

            // JOINTS_0 must be UNSIGNED_BYTE or UNSIGNED_SHORT.
            modifiedAttribute = null
            const array = attribute.array

            if (attributeName === 'JOINTS_0' && !(array instanceof Uint16Array) && !(array instanceof Uint8Array)) {
                console.warn('GLTFExporter: Attribute "skinIndex" converted to type UNSIGNED_SHORT.')
                modifiedAttribute = new BufferAttribute(new Uint16Array(array), attribute.itemSize, attribute.normalized)
            }

            const accessor = this.processAccessor(modifiedAttribute || attribute, geometry)

            if (accessor !== null) {
                attributes[attributeName] = accessor
                cache.attributes.set(this.getUID(attribute), accessor)
            }
        }

        if (originalNormal !== undefined) geometry.setAttribute('normal', originalNormal)

        // Skip if no exportable attributes found
        if (Object.keys(attributes).length === 0) return null

        // Morph targets
        if (mesh.morphTargetInfluences !== undefined && mesh.morphTargetInfluences.length > 0) {
            const weights = []
            const targetNames = []
            const reverseDictionary = {}

            if (mesh.morphTargetDictionary !== undefined) {
                for (const key in mesh.morphTargetDictionary) {
                    reverseDictionary[mesh.morphTargetDictionary[key]] = key
                }
            }

            for (let i = 0; i < mesh.morphTargetInfluences.length; ++i) {
                const target = {}
                let warned = false

                for (const attributeName in geometry.morphAttributes) {
                    // glTF 2.0 morph supports only POSITION/NORMAL/TANGENT.
                    // Three.js doesn't support TANGENT yet.

                    if (attributeName !== 'position' && attributeName !== 'normal') {
                        if (!warned) {
                            console.warn('GLTFExporter: Only POSITION and NORMAL morph are supported.')
                            warned = true
                        }

                        continue
                    }

                    const attribute = geometry.morphAttributes[attributeName][i]
                    const gltfAttributeName = attributeName.toUpperCase()

                    // Three.js morph attribute has absolute values while the one of glTF has relative values.
                    //
                    // glTF 2.0 Specification:
                    // https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#morph-targets

                    const baseAttribute = geometry.attributes[attributeName]

                    if (cache.attributes.has(this.getUID(attribute))) {
                        target[gltfAttributeName] = cache.attributes.get(this.getUID(attribute))
                        continue
                    }

                    // Clones attribute not to override
                    const relativeAttribute = attribute.clone()

                    if (!geometry.morphTargetsRelative) {
                        for (let j = 0, jl = attribute.count; j < jl; j++) {
                            relativeAttribute.setXYZ(j, attribute.getX(j) - baseAttribute.getX(j), attribute.getY(j) - baseAttribute.getY(j), attribute.getZ(j) - baseAttribute.getZ(j))
                        }
                    }

                    target[gltfAttributeName] = this.processAccessor(relativeAttribute, geometry)
                    cache.attributes.set(this.getUID(baseAttribute), target[gltfAttributeName])
                }

                targets.push(target)

                weights.push(mesh.morphTargetInfluences[i])

                if (mesh.morphTargetDictionary !== undefined) targetNames.push(reverseDictionary[i])
            }

            meshDef.weights = weights

            if (targetNames.length > 0) {
                meshDef.extras = {}
                meshDef.extras.targetNames = targetNames
            }
        }

        const isMultiMaterial = Array.isArray(mesh.material)

        if (isMultiMaterial && geometry.groups.length === 0) return null

        const materials = isMultiMaterial ? mesh.material : [mesh.material]
        const groups = isMultiMaterial ? geometry.groups : [{ materialIndex: 0, start: undefined, count: undefined }]

        for (let i = 0, il = groups.length; i < il; i++) {
            const primitive = {
                mode: mode,
                attributes: attributes
            }

            this.serializeUserData(geometry, primitive)

            if (targets.length > 0) primitive.targets = targets

            if (geometry.index !== null) {
                let cacheKey = this.getUID(geometry.index)

                if (groups[i].start !== undefined || groups[i].count !== undefined) {
                    cacheKey += ':' + groups[i].start + ':' + groups[i].count
                }

                if (cache.attributes.has(cacheKey)) {
                    primitive.indices = cache.attributes.get(cacheKey)
                } else {
                    primitive.indices = this.processAccessor(geometry.index, geometry, groups[i].start, groups[i].count)
                    cache.attributes.set(cacheKey, primitive.indices)
                }

                if (primitive.indices === null) delete primitive.indices
            }

            const material = this.processMaterial(materials[groups[i].materialIndex])

            if (material !== null) primitive.material = material

            primitives.push(primitive)
        }

        meshDef.primitives = primitives

        if (!json.meshes) json.meshes = []

        this._invokeAll(function(ext) {
            ext.writeMesh && ext.writeMesh(mesh, meshDef)
        })

        const index = json.meshes.push(meshDef) - 1
        cache.meshes.set(meshCacheKey, index)
        return index
    }

    /**
     * Process camera
     * @param  {THREE.Camera} camera Camera to process
     * @return {Integer}      Index of the processed mesh in the "camera" array
     */
    processCamera(camera) {
        const json = this.json

        if (!json.cameras) json.cameras = []

        const isOrtho = camera.isOrthographicCamera

        const cameraDef = {
            type: isOrtho ? 'orthographic' : 'perspective'
        }

        if (isOrtho) {
            cameraDef.orthographic = {
                xmag: camera.right * 2,
                ymag: camera.top * 2,
                zfar: camera.far <= 0 ? 0.001 : camera.far,
                znear: camera.near < 0 ? 0 : camera.near
            }
        } else {
            cameraDef.perspective = {
                aspectRatio: camera.aspect,
                yfov: MathUtils.degToRad(camera.fov),
                zfar: camera.far <= 0 ? 0.001 : camera.far,
                znear: camera.near < 0 ? 0 : camera.near
            }
        }

        // Question: Is saving "type" as name intentional?
        if (camera.name !== '') cameraDef.name = camera.type

        return json.cameras.push(cameraDef) - 1
    }

    /**
     * Creates glTF animation entry from AnimationClip object.
     *
     * Status:
     * - Only properties listed in PATH_PROPERTIES may be animated.
     *
     * @param {THREE.AnimationClip} clip
     * @param {THREE.Object3D} root
     * @return {number|null}
     */
    processAnimation(clip, root) {
        const json = this.json
        const nodeMap = this.nodeMap

        if (!json.animations) json.animations = []

        clip = GLTFExporter.Utils.mergeMorphTargetTracks(clip.clone(), root)

        const tracks = clip.tracks
        const channels = []
        const samplers = []

        for (let i = 0; i < tracks.length; ++i) {
            const track = tracks[i]
            const trackBinding = PropertyBinding.parseTrackName(track.name)
            let trackNode = PropertyBinding.findNode(root, trackBinding.nodeName)
            const trackProperty = PATH_PROPERTIES[trackBinding.propertyName]

            if (trackBinding.objectName === 'bones') {
                if (trackNode.isSkinnedMesh === true) {
                    trackNode = trackNode.skeleton.getBoneByName(trackBinding.objectIndex)
                } else {
                    trackNode = undefined
                }
            }

            if (!trackNode || !trackProperty) {
                console.warn('THREE.GLTFExporter: Could not export animation track "%s".', track.name)
                return null
            }

            const inputItemSize = 1
            let outputItemSize = track.values.length / track.times.length

            if (trackProperty === PATH_PROPERTIES.morphTargetInfluences) {
                outputItemSize /= trackNode.morphTargetInfluences.length
            }

            let interpolation

            // @TODO export CubicInterpolant(InterpolateSmooth) as CUBICSPLINE

            // Detecting glTF cubic spline interpolant by checking factory method's special property
            // GLTFCubicSplineInterpolant is a custom interpolant and track doesn't return
            // valid value from .getInterpolation().
            if (track.createInterpolant.isInterpolantFactoryMethodGLTFCubicSpline === true) {
                interpolation = 'CUBICSPLINE'

                // itemSize of CUBICSPLINE keyframe is 9
                // (VEC3 * 3: inTangent, splineVertex, and outTangent)
                // but needs to be stored as VEC3 so dividing by 3 here.
                outputItemSize /= 3
            } else if (track.getInterpolation() === InterpolateDiscrete) {
                interpolation = 'STEP'
            } else {
                interpolation = 'LINEAR'
            }

            samplers.push({
                input: this.processAccessor(new BufferAttribute(track.times, inputItemSize)),
                output: this.processAccessor(new BufferAttribute(track.values, outputItemSize)),
                interpolation: interpolation
            })

            channels.push({
                sampler: samplers.length - 1,
                target: {
                    node: nodeMap.get(trackNode),
                    path: trackProperty
                }
            })
        }

        json.animations.push({
            name: clip.name || 'clip_' + json.animations.length,
            samplers: samplers,
            channels: channels
        })

        return json.animations.length - 1
    }

    /**
     * @param {THREE.Object3D} object
     * @return {number|null}
     */
    processSkin(object) {
        const json = this.json
        const nodeMap = this.nodeMap

        const node = json.nodes[nodeMap.get(object)]

        const skeleton = object.skeleton

        if (skeleton === undefined) return null

        const rootJoint = object.skeleton.bones[0]

        if (rootJoint === undefined) return null

        const joints = []
        const inverseBindMatrices = new Float32Array(skeleton.bones.length * 16)
        const temporaryBoneInverse = new Matrix4()

        for (let i = 0; i < skeleton.bones.length; ++i) {
            joints.push(nodeMap.get(skeleton.bones[i]))
            temporaryBoneInverse.copy(skeleton.boneInverses[i])
            temporaryBoneInverse.multiply(object.bindMatrix).toArray(inverseBindMatrices, i * 16)
        }

        if (json.skins === undefined) json.skins = []

        json.skins.push({
            inverseBindMatrices: this.processAccessor(new BufferAttribute(inverseBindMatrices, 16)),
            joints: joints,
            skeleton: nodeMap.get(rootJoint)
        })

        const skinIndex = (node.skin = json.skins.length - 1)

        return skinIndex
    }

    /**
     * Process Object3D node
     * @param  {THREE.Object3D} node Object3D to processNode
     * @return {Integer} Index of the node in the nodes list
     */
    processNode(object) {
        const json = this.json
        const options = this.options
        const nodeMap = this.nodeMap

        if (!json.nodes) json.nodes = []

        const nodeDef = {}

        if (options.trs) {
            const rotation = object.quaternion.toArray()
            const position = object.position.toArray()
            const scale = object.scale.toArray()

            if (!equalArray(rotation, [0, 0, 0, 1])) {
                nodeDef.rotation = rotation
            }

            if (!equalArray(position, [0, 0, 0])) {
                nodeDef.translation = position
            }

            if (!equalArray(scale, [1, 1, 1])) {
                nodeDef.scale = scale
            }
        } else {
            if (object.matrixAutoUpdate) {
                object.updateMatrix()
            }

            if (isIdentityMatrix(object.matrix) === false) {
                nodeDef.matrix = object.matrix.elements
            }
        }

        // We don't export empty strings name because it represents no-name in Three.js.
        if (object.name !== '') nodeDef.name = String(object.name)

        this.serializeUserData(object, nodeDef)

        if (object.isMesh || object.isLine || object.isPoints) {
            const meshIndex = this.processMesh(object)

            if (meshIndex !== null) nodeDef.mesh = meshIndex
        } else if (object.isCamera) {
            nodeDef.camera = this.processCamera(object)
        }

        if (object.isSkinnedMesh) this.skins.push(object)

        if (object.children.length > 0) {
            const children = []

            for (let i = 0, l = object.children.length; i < l; i++) {
                const child = object.children[i]

                if (child.visible || options.onlyVisible === false) {
                    const nodeIndex = this.processNode(child)

                    if (nodeIndex !== null) children.push(nodeIndex)
                }
            }

            if (children.length > 0) nodeDef.children = children
        }

        this._invokeAll(function(ext) {
            ext.writeNode && ext.writeNode(object, nodeDef)
        })

        const nodeIndex = json.nodes.push(nodeDef) - 1
        nodeMap.set(object, nodeIndex)
        return nodeIndex
    }

    /**
     * Process Scene
     * @param  {Scene} node Scene to process
     */
    processScene(scene) {
        const json = this.json
        const options = this.options

        if (!json.scenes) {
            json.scenes = []
            json.scene = 0
        }

        const sceneDef = {}

        if (scene.name !== '') sceneDef.name = scene.name

        json.scenes.push(sceneDef)

        const nodes = []

        for (let i = 0, l = scene.children.length; i < l; i++) {
            const child = scene.children[i]

            if (child.visible || options.onlyVisible === false) {
                // bimrocket, save matrix
                let matrix = child.matrix
                // bimrocket, rotate object -90 deg
                child.matrix = new Matrix4().makeRotationX(-Math.PI / 2).multiply(matrix)

                const nodeIndex = this.processNode(child)

                // bimrocket, restore matrix
                child.matrix = matrix

                if (nodeIndex !== null) nodes.push(nodeIndex)
            }
        }

        if (nodes.length > 0) sceneDef.nodes = nodes

        this.serializeUserData(scene, sceneDef)
    }

    /**
     * Creates a Scene to hold a list of objects and parse it
     * @param  {Array} objects List of objects to process
     */
    processObjects(objects) {
        const scene = new Scene()
        scene.name = 'AuxScene'

        for (let i = 0; i < objects.length; i++) {
            // We push directly to children instead of calling `add` to prevent
            // modify the .parent and break its original scene and hierarchy
            scene.children.push(objects[i])
        }

        this.processScene(scene)
    }

    /**
     * @param {THREE.Object3D|Array<THREE.Object3D>} input
     */
    processInput(input) {
        const options = this.options

        input = input instanceof Array ? input : [input]

        this._invokeAll(function(ext) {
            ext.beforeParse && ext.beforeParse(input)
        })

        const objectsWithoutScene = []

        for (let i = 0; i < input.length; i++) {
            if (
                input[i] instanceof Scene ||
                // bimrocket
                (input[i] instanceof Group && input.length === 1)
            ) {
                this.processScene(input[i])
            } else {
                objectsWithoutScene.push(input[i])
            }
        }

        if (objectsWithoutScene.length > 0) this.processObjects(objectsWithoutScene)

        for (let i = 0; i < this.skins.length; ++i) {
            this.processSkin(this.skins[i])
        }

        for (let i = 0; i < options.animations.length; ++i) {
            this.processAnimation(options.animations[i], input[0])
        }

        this._invokeAll(function(ext) {
            ext.afterParse && ext.afterParse(input)
        })
    }

    _invokeAll(func) {
        for (let i = 0, il = this.plugins.length; i < il; i++) {
            func(this.plugins[i])
        }
    }
}

/**
 * Punctual Lights Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_lights_punctual
 */
class GLTFLightExtension {
    constructor(writer) {
        this.writer = writer
        this.name = 'KHR_lights_punctual'
    }

    writeNode(light, nodeDef) {
        if (!light.isLight) return

        if (!light.isDirectionalLight && !light.isPointLight && !light.isSpotLight) {
            console.warn('THREE.GLTFExporter: Only directional, point, and spot lights are supported.', light)
            return
        }

        const writer = this.writer
        const json = writer.json
        const extensionsUsed = writer.extensionsUsed

        const lightDef = {}

        if (light.name) lightDef.name = light.name

        lightDef.color = light.color.toArray()

        lightDef.intensity = light.intensity

        if (light.isDirectionalLight) {
            lightDef.type = 'directional'
        } else if (light.isPointLight) {
            lightDef.type = 'point'

            if (light.distance > 0) lightDef.range = light.distance
        } else if (light.isSpotLight) {
            lightDef.type = 'spot'

            if (light.distance > 0) lightDef.range = light.distance

            lightDef.spot = {}
            lightDef.spot.innerConeAngle = (light.penumbra - 1.0) * light.angle * -1.0
            lightDef.spot.outerConeAngle = light.angle
        }

        if (light.decay !== undefined && light.decay !== 2) {
            console.warn('THREE.GLTFExporter: Light decay may be lost. glTF is physically-based, ' + 'and expects light.decay=2.')
        }

        if (light.target && (light.target.parent !== light || light.target.position.x !== 0 || light.target.position.y !== 0 || light.target.position.z !== -1)) {
            console.warn('THREE.GLTFExporter: Light direction may be lost. For best results, ' + 'make light.target a child of the light with position 0,0,-1.')
        }

        if (!extensionsUsed[this.name]) {
            json.extensions = json.extensions || {}
            json.extensions[this.name] = { lights: [] }
            extensionsUsed[this.name] = true
        }

        const lights = json.extensions[this.name].lights
        lights.push(lightDef)

        nodeDef.extensions = nodeDef.extensions || {}
        nodeDef.extensions[this.name] = { light: lights.length - 1 }
    }
}

/**
 * Unlit Materials Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_unlit
 */
class GLTFMaterialsUnlitExtension {
    constructor(writer) {
        this.writer = writer
        this.name = 'KHR_materials_unlit'
    }

    writeMaterial(material, materialDef) {
        if (!material.isMeshBasicMaterial) return

        const writer = this.writer
        const extensionsUsed = writer.extensionsUsed

        materialDef.extensions = materialDef.extensions || {}
        materialDef.extensions[this.name] = {}

        extensionsUsed[this.name] = true

        materialDef.pbrMetallicRoughness.metallicFactor = 0.0
        materialDef.pbrMetallicRoughness.roughnessFactor = 0.9
    }
}

/**
 * Specular-Glossiness Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Archived/KHR_materials_pbrSpecularGlossiness
 */
class GLTFMaterialsPBRSpecularGlossiness {
    constructor(writer) {
        this.writer = writer
        this.name = 'KHR_materials_pbrSpecularGlossiness'
    }

    writeMaterial(material, materialDef) {
        if (!material.isGLTFSpecularGlossinessMaterial) return

        const writer = this.writer
        const extensionsUsed = writer.extensionsUsed

        const extensionDef = {}

        if (materialDef.pbrMetallicRoughness.baseColorFactor) {
            extensionDef.diffuseFactor = materialDef.pbrMetallicRoughness.baseColorFactor
        }

        const specularFactor = [1, 1, 1]
        material.specular.toArray(specularFactor, 0)
        extensionDef.specularFactor = specularFactor
        extensionDef.glossinessFactor = material.glossiness

        if (materialDef.pbrMetallicRoughness.baseColorTexture) {
            extensionDef.diffuseTexture = materialDef.pbrMetallicRoughness.baseColorTexture
        }

        if (material.specularMap) {
            const specularMapDef = { index: writer.processTexture(material.specularMap) }
            writer.applyTextureTransform(specularMapDef, material.specularMap)
            extensionDef.specularGlossinessTexture = specularMapDef
        }

        materialDef.extensions = materialDef.extensions || {}
        materialDef.extensions[this.name] = extensionDef
        extensionsUsed[this.name] = true
    }
}

/**
 * Clearcoat Materials Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_clearcoat
 */
class GLTFMaterialsClearcoatExtension {
    constructor(writer) {
        this.writer = writer
        this.name = 'KHR_materials_clearcoat'
    }

    writeMaterial(material, materialDef) {
        if (!material.isMeshPhysicalMaterial) return

        const writer = this.writer
        const extensionsUsed = writer.extensionsUsed

        const extensionDef = {}

        extensionDef.clearcoatFactor = material.clearcoat

        if (material.clearcoatMap) {
            const clearcoatMapDef = { index: writer.processTexture(material.clearcoatMap) }
            writer.applyTextureTransform(clearcoatMapDef, material.clearcoatMap)
            extensionDef.clearcoatTexture = clearcoatMapDef
        }

        extensionDef.clearcoatRoughnessFactor = material.clearcoatRoughness

        if (material.clearcoatRoughnessMap) {
            const clearcoatRoughnessMapDef = { index: writer.processTexture(material.clearcoatRoughnessMap) }
            writer.applyTextureTransform(clearcoatRoughnessMapDef, material.clearcoatRoughnessMap)
            extensionDef.clearcoatRoughnessTexture = clearcoatRoughnessMapDef
        }

        if (material.clearcoatNormalMap) {
            const clearcoatNormalMapDef = { index: writer.processTexture(material.clearcoatNormalMap) }
            writer.applyTextureTransform(clearcoatNormalMapDef, material.clearcoatNormalMap)
            extensionDef.clearcoatNormalTexture = clearcoatNormalMapDef
        }

        materialDef.extensions = materialDef.extensions || {}
        materialDef.extensions[this.name] = extensionDef

        extensionsUsed[this.name] = true
    }
}

/**
 * Transmission Materials Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_transmission
 */
class GLTFMaterialsTransmissionExtension {
    constructor(writer) {
        this.writer = writer
        this.name = 'KHR_materials_transmission'
    }

    writeMaterial(material, materialDef) {
        if (!material.isMeshPhysicalMaterial || material.transmission === 0) return

        const writer = this.writer
        const extensionsUsed = writer.extensionsUsed

        const extensionDef = {}

        extensionDef.transmissionFactor = material.transmission

        if (material.transmissionMap) {
            const transmissionMapDef = { index: writer.processTexture(material.transmissionMap) }
            writer.applyTextureTransform(transmissionMapDef, material.transmissionMap)
            extensionDef.transmissionTexture = transmissionMapDef
        }

        materialDef.extensions = materialDef.extensions || {}
        materialDef.extensions[this.name] = extensionDef

        extensionsUsed[this.name] = true
    }
}

/**
 * Materials Volume Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_volume
 */
class GLTFMaterialsVolumeExtension {
    constructor(writer) {
        this.writer = writer
        this.name = 'KHR_materials_volume'
    }

    writeMaterial(material, materialDef) {
        if (!material.isMeshPhysicalMaterial || material.transmission === 0) return

        const writer = this.writer
        const extensionsUsed = writer.extensionsUsed

        const extensionDef = {}

        extensionDef.thicknessFactor = material.thickness

        if (material.thicknessMap) {
            const thicknessMapDef = { index: writer.processTexture(material.thicknessMap) }
            writer.applyTextureTransform(thicknessMapDef, material.thicknessMap)
            extensionDef.thicknessTexture = thicknessMapDef
        }

        extensionDef.attenuationDistance = material.attenuationDistance
        extensionDef.attenuationColor = material.attenuationColor.toArray()

        materialDef.extensions = materialDef.extensions || {}
        materialDef.extensions[this.name] = extensionDef

        extensionsUsed[this.name] = true
    }
}

/**
 * Static utility functions
 */
GLTFExporter.Utils = {
    insertKeyframe: function(track, time) {
        const tolerance = 0.001 // 1ms
        const valueSize = track.getValueSize()

        const times = new track.TimeBufferType(track.times.length + 1)
        const values = new track.ValueBufferType(track.values.length + valueSize)
        const interpolant = track.createInterpolant(new track.ValueBufferType(valueSize))

        let index

        if (track.times.length === 0) {
            times[0] = time

            for (let i = 0; i < valueSize; i++) {
                values[i] = 0
            }

            index = 0
        } else if (time < track.times[0]) {
            if (Math.abs(track.times[0] - time) < tolerance) return 0

            times[0] = time
            times.set(track.times, 1)

            values.set(interpolant.evaluate(time), 0)
            values.set(track.values, valueSize)

            index = 0
        } else if (time > track.times[track.times.length - 1]) {
            if (Math.abs(track.times[track.times.length - 1] - time) < tolerance) {
                return track.times.length - 1
            }

            times[times.length - 1] = time
            times.set(track.times, 0)

            values.set(track.values, 0)
            values.set(interpolant.evaluate(time), track.values.length)

            index = times.length - 1
        } else {
            for (let i = 0; i < track.times.length; i++) {
                if (Math.abs(track.times[i] - time) < tolerance) return i

                if (track.times[i] < time && track.times[i + 1] > time) {
                    times.set(track.times.slice(0, i + 1), 0)
                    times[i + 1] = time
                    times.set(track.times.slice(i + 1), i + 2)

                    values.set(track.values.slice(0, (i + 1) * valueSize), 0)
                    values.set(interpolant.evaluate(time), (i + 1) * valueSize)
                    values.set(track.values.slice((i + 1) * valueSize), (i + 2) * valueSize)

                    index = i + 1

                    break
                }
            }
        }

        track.times = times
        track.values = values

        return index
    },

    mergeMorphTargetTracks: function(clip, root) {
        const tracks = []
        const mergedTracks = {}
        const sourceTracks = clip.tracks

        for (let i = 0; i < sourceTracks.length; ++i) {
            let sourceTrack = sourceTracks[i]
            const sourceTrackBinding = PropertyBinding.parseTrackName(sourceTrack.name)
            const sourceTrackNode = PropertyBinding.findNode(root, sourceTrackBinding.nodeName)

            if (sourceTrackBinding.propertyName !== 'morphTargetInfluences' || sourceTrackBinding.propertyIndex === undefined) {
                // Tracks that don't affect morph targets, or that affect all morph targets together, can be left as-is.
                tracks.push(sourceTrack)
                continue
            }

            if (sourceTrack.createInterpolant !== sourceTrack.InterpolantFactoryMethodDiscrete && sourceTrack.createInterpolant !== sourceTrack.InterpolantFactoryMethodLinear) {
                if (sourceTrack.createInterpolant.isInterpolantFactoryMethodGLTFCubicSpline) {
                    // This should never happen, because glTF morph target animations
                    // affect all targets already.
                    throw new Error('THREE.GLTFExporter: Cannot merge tracks with glTF CUBICSPLINE interpolation.')
                }

                console.warn('THREE.GLTFExporter: Morph target interpolation mode not yet supported. Using LINEAR instead.')

                sourceTrack = sourceTrack.clone()
                sourceTrack.setInterpolation(InterpolateLinear)
            }

            const targetCount = sourceTrackNode.morphTargetInfluences.length
            const targetIndex = sourceTrackNode.morphTargetDictionary[sourceTrackBinding.propertyIndex]

            if (targetIndex === undefined) {
                throw new Error('THREE.GLTFExporter: Morph target name not found: ' + sourceTrackBinding.propertyIndex)
            }

            let mergedTrack

            // If this is the first time we've seen this object, create a new
            // track to store merged keyframe data for each morph target.
            if (mergedTracks[sourceTrackNode.uuid] === undefined) {
                mergedTrack = sourceTrack.clone()

                const values = new mergedTrack.ValueBufferType(targetCount * mergedTrack.times.length)

                for (let j = 0; j < mergedTrack.times.length; j++) {
                    values[j * targetCount + targetIndex] = mergedTrack.values[j]
                }

                // We need to take into consideration the intended target node
                // of our original un-merged morphTarget animation.
                mergedTrack.name = (sourceTrackBinding.nodeName || '') + '.morphTargetInfluences'
                mergedTrack.values = values

                mergedTracks[sourceTrackNode.uuid] = mergedTrack
                tracks.push(mergedTrack)

                continue
            }

            const sourceInterpolant = sourceTrack.createInterpolant(new sourceTrack.ValueBufferType(1))

            mergedTrack = mergedTracks[sourceTrackNode.uuid]

            // For every existing keyframe of the merged track, write a (possibly
            // interpolated) value from the source track.
            for (let j = 0; j < mergedTrack.times.length; j++) {
                mergedTrack.values[j * targetCount + targetIndex] = sourceInterpolant.evaluate(mergedTrack.times[j])
            }

            // For every existing keyframe of the source track, write a (possibly
            // new) keyframe to the merged track. Values from the previous loop may
            // be written again, but keyframes are de-duplicated.
            for (let j = 0; j < sourceTrack.times.length; j++) {
                const keyframeIndex = this.insertKeyframe(mergedTrack, sourceTrack.times[j])
                mergedTrack.values[keyframeIndex * targetCount + targetIndex] = sourceTrack.values[j]
            }
        }

        clip.tracks = tracks

        return clip
    }
}

export { GLTFExporter }