center_scale_obj.js

"use strict";

// centers and scales all *.obj and saves results as *.2.obj
// can also keep 3d viewers from jittering

const fs = require('fs');
const readline = require('readline');
const path = require('path');
const OBJ_DIR = './downloaded_files/obj';

for (let i of fs.readdirSync(OBJ_DIR)) {
	i = path.resolve(OBJ_DIR, i);
	if (!fs.statSync(i).isDirectory()) continue;

	for (let j of fs.readdirSync(i)) {
		j = path.resolve(i, j);
		if (!/\.obj$/.test(j) || /\.2\.obj$/.test(j)) continue;
		if (!fs.statSync(j).isFile()) continue;

		scaleMoveObj(j, `${j.match(/(.*)\.obj$/)[1]}.2.obj`);
	}
}

const SCALE = 10;

function scaleMoveObj(file_in, file_out) {

	if (fs.existsSync(file_out)) {
		fs.unlinkSync(file_out);
	}

	const io = readline.createInterface({
		input: fs.createReadStream(file_in),
		terminal: false,
	});

	let min_x = Infinity, max_x = -Infinity;
	let min_y = Infinity, max_y = -Infinity;
	let min_z = Infinity, max_z = -Infinity;

	io.on('line', line => {
		if (!/^v /.test(line))
			return;
		let [x, y, z] = line.split(' ').slice(1).map(parseFloat);
		min_x = Math.min(x, min_x);
		min_y = Math.min(y, min_y);
		min_z = Math.min(z, min_z);
		max_x = Math.max(x, max_x);
		max_y = Math.max(y, max_y);
		max_z = Math.max(z, max_z);
	}).on('close', () => {
		const center_x = (max_x + min_x) / 2;
		const center_y = (max_y + min_y) / 2;
		const center_z = (max_z + min_z) / 2;
		const distance_x = Math.abs(max_x - min_x);
		const distance_y = Math.abs(max_y - min_y);
		const distance_z = Math.abs(max_z - min_z);
		const max_distance = Math.max(distance_x, distance_y, distance_z);

		const io = readline.createInterface({
			input: fs.createReadStream(file_in),
			output: fs.createWriteStream(file_out),
		});

		io.on('line', line => {
			if (!/^v /.test(line))
				return io.output.write(`${line}\n`);
			let [x, y, z] = line.split(' ').slice(1).map(parseFloat);
			x = (x - center_x) / max_distance * SCALE;
			y = (y - center_y) / max_distance * SCALE;
			z = (z - center_z) / max_distance * SCALE;
			io.output.write(`v ${x} ${y} ${z}\n`);
		}).on('close', () => {
			console.error(`done. saved as ${file_out}`);
		});
	});
}