Reduce an .obj file to its key components for structure evaluation

conciseObj.js

var inputPath = @"c:\temp\example.obj";
var outputPath = @"c:\temp\results.txt";

var reader = new System.IO.StreamReader(inputPath);
var output = System.IO.File.CreateText(outputPath);
        
var v = 0;
var vn = 0;
var f = 0;
string line;

while ((line = reader.ReadLine()) != null)
{
	var type = line.Substring(0, 2).Trim();
	
	switch(type) {
	
	case "g":
		v = 0;
		vn = 0;
		f = 0;
		break;
	case "v":
	
		v++;
		
		if (v > 3) line = null;
		break;
		
	case "vn":
		vn++;
		
		if (vn > 3) line = null;
		break;
	case "f":
		f++;
		
		if (f > 1) line = null;
		break;
	case "us":
		f = 0;
		break;
	}
	
	if (line != null)
	{
		output.WriteLine(line);
	}
}

output.Close();