@loaders.gl/i3s
Version:
i3s .
98 lines (97 loc) • 3.44 kB
JavaScript
// loaders.gl
// SPDX-License-Identifier: MIT
// Copyright (c) vis.gl contributors
import { STRING_ATTRIBUTE_TYPE, OBJECT_ID_ATTRIBUTE_TYPE, FLOAT_64_TYPE, INT_16_ATTRIBUTE_TYPE } from "./constants.js";
/**
* Get particular tile and creates attribute object inside.
* @param arrayBuffer
* @param {Object} options
* @returns {Promise<object>}
*/
export function parseI3STileAttribute(arrayBuffer, options) {
const { attributeName, attributeType } = options;
if (!attributeName) {
return {};
}
return {
[attributeName]: attributeType ? parseAttribute(attributeType, arrayBuffer) : null
};
}
/**
* Parse attributes based on attribute type.
* @param {String} attributeType
* @param arrayBuffer
* @returns
*/
function parseAttribute(attributeType, arrayBuffer) {
switch (attributeType) {
case STRING_ATTRIBUTE_TYPE:
return parseStringsAttribute(arrayBuffer);
case OBJECT_ID_ATTRIBUTE_TYPE:
return parseShortNumberAttribute(arrayBuffer);
case FLOAT_64_TYPE:
return parseFloatAttribute(arrayBuffer);
case INT_16_ATTRIBUTE_TYPE:
return parseInt16ShortNumberAttribute(arrayBuffer);
default:
return parseShortNumberAttribute(arrayBuffer);
}
}
/**
* Parse short number attribute.
* Short Integer spec - https://github.com/Esri/i3s-spec/blob/master/docs/1.7/attributeStorageInfo.cmn.md
* @param arrayBuffer
* @returns
*/
function parseShortNumberAttribute(arrayBuffer) {
const countOffset = 4;
return new Uint32Array(arrayBuffer, countOffset);
}
/**
* Parse Int16 short number attribute.
* Parsing of such data is not documented. Added to handle Building Scene Layer Tileset attributes data.
* @param arrayBuffer
* @returns
*/
function parseInt16ShortNumberAttribute(arrayBuffer) {
const countOffset = 4;
return new Int16Array(arrayBuffer, countOffset);
}
/**
* Parse float attribute.
* Double Spec - https://github.com/Esri/i3s-spec/blob/master/docs/1.7/attributeStorageInfo.cmn.md
* @param arrayBuffer
* @returns
*/
function parseFloatAttribute(arrayBuffer) {
const countOffset = 8;
return new Float64Array(arrayBuffer, countOffset);
}
/**
* Parse string attribute.
* String spec - https://github.com/Esri/i3s-spec/blob/master/docs/1.7/attributeStorageInfo.cmn.md
* @param arrayBuffer
* @returns list of strings
*/
function parseStringsAttribute(arrayBuffer) {
const stringsCountOffset = 0;
const dataOffset = 8;
const bytesPerStringSize = 4;
const stringsArray = [];
try {
// Use DataView to avoid multiple of 4 error on Uint32Array constructor
const stringsCount = new DataView(arrayBuffer, stringsCountOffset, bytesPerStringSize).getUint32(stringsCountOffset, true);
const stringSizes = new Uint32Array(arrayBuffer, dataOffset, stringsCount);
let stringOffset = dataOffset + stringsCount * bytesPerStringSize;
for (const stringByteSize of stringSizes) {
const textDecoder = new TextDecoder('utf-8');
const stringAttribute = new Uint8Array(arrayBuffer, stringOffset, stringByteSize);
stringsArray.push(textDecoder.decode(stringAttribute));
stringOffset += stringByteSize;
}
}
catch (error) {
console.error('Parse string attribute error: ', error.message); // eslint-disable-line
}
return stringsArray;
}