Converting OBJ Files to glTF and GLB Files
Overview These are notes on how to convert OBJ files to glTF and GLB files.
Target Data The target is the “Ishibuchi Family Globe” from the “Kikuchi City / Digital Archive.”
https://adeac.jp/kikuchi-city/catalog/e0001
The OBJ file can be accessed from the following URL.
https://adeac.jp/viewitem/kikuchi-city/viewer/3d/dc-e0097/models/Kikuchi_Globe_180820.obj
Downloading the Target Data Download the library.
npm i axios Prepare the following file.
const axios = require('axios'); const fs = require('fs'); const path = require('path'); // Function to download a file from a specified URL async function downloadFile(url, outputPath) { const writer = fs.createWriteStream(outputPath); const response = await axios({ url, method: 'GET', responseType: 'stream', }); response.data.pipe(writer); return new Promise((resolve, reject) => { writer.on('finish', resolve); writer.on('error', reject); }); } // Load .obj file and download related files async function processObjFile(objUrl, outputDir) { try { // Download .obj file and get its content const objResponse = await axios.get(objUrl); const objContent = objResponse.data; // Save .obj file const objFileName = path.basename(objUrl); const objFilePath = path.join(outputDir, objFileName); fs.writeFileSync(objFilePath, objContent); console.log(`Downloaded OBJ file: ${objFilePath}`); // Search for .mtl file path const mtlMatch = objContent.match(/^mtllib\s+(.+)$/m); if (mtlMatch) { const mtlFileName = mtlMatch[1]; const mtlUrl = new URL(mtlFileName, objUrl).href; const mtlFilePath = path.join(outputDir, mtlFileName); // Download .mtl file await downloadFile(mtlUrl, mtlFilePath); console.log(`Downloaded MTL file: ${mtlFilePath}`); // Get .mtl file content and find related files const mtlContent = fs.readFileSync(mtlFilePath, 'utf-8'); const textureMatches = [...mtlContent.matchAll(/^map_Kd\s+(.+)$/gm)]; for (const match of textureMatches) { const textureFileName = match[1]; const textureUrl = new URL(textureFileName, objUrl).href; const textureFilePath = path.join(outputDir, path.basename(textureFileName)); // Download texture image await downloadFile(textureUrl, textureFilePath); console.log(`Downloaded texture file: ${textureFilePath}`); } } else { console.log('No MTL file referenced in the OBJ file.'); } } catch (error) { console.error(`Error processing OBJ file: ${error.message}`); } } // Usage example const objUrl = 'https://adeac.jp/viewitem/kikuchi-city/viewer/3d/dc-e0097/models/Kikuchi_Globe_180820.obj'; const outputDir = './downloads'; if (!fs.existsSync(outputDir)) { fs.mkdirSync(outputDir, { recursive: true }); } processObjFile(objUrl, outputDir); Execute it.
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December 30, 2024 · Updated: December 30, 2024 · 2 min · Nakamura
