Add obj + mtl + atlas recreator (not implement)

[mrqsdf]

I add class for future implementation of create atlas with recreate obj file

exemple code for refactor :

public class ObjAtlasExample {

    public static void main(String[] args) throws Exception {
        long startTotal = System.currentTimeMillis();

        // Dossier d'entrée (où se trouvent les .obj, .mtl, textures)
        Path inputDir = Path.of("models_in");
        // Dossier de sortie (où seront écrits les nouveaux .obj/.mtl/atlas)
        Path outputDir = Path.of("models_out");

        if (!Files.exists(inputDir) || !Files.isDirectory(inputDir)) {
            System.err.println("[ERROR] Input directory does not exist or is not a directory: " + inputDir);
            return;
        }

        // Prépare les outils une seule fois
        ObjParser objParser = new ObjParser();
        TextureAtlasBuilder atlasBuilder = new TextureAtlasBuilder();
        ObjAtlasRewriter rewriter = new ObjAtlasRewriter();
        ObjWriter objWriter = new ObjWriter();
        MtlWriter mtlWriter = new MtlWriter();

        // Liste tous les .obj dans le dossier d'entrée (récursif)
        List<Path> objFiles;
        try (Stream<Path> stream = Files.walk(inputDir)) {
            objFiles = stream
                    .filter(Files::isRegularFile)
                    .filter(p -> p.toString().toLowerCase(Locale.ROOT).endsWith(".obj"))
                    .toList();
        }

        if (objFiles.isEmpty()) {
            System.out.println("[INFO] No OBJ files found in: " + inputDir);
        } else {
            System.out.println("[INFO] Found " + objFiles.size() + " OBJ file(s) to process.");
        }

        for (Path objPath : objFiles) {
            long startFile = System.currentTimeMillis();
            System.out.println("--------------------------------------------------");
            System.out.println("[INFO] Processing OBJ: " + objPath);

            try {
                // 1) Parse original OBJ + MTL
                ObjModel originalModel = objParser.parse(objPath);

                // Dossier où se trouvent le .obj et les textures d'origine
                Path objParent = objPath.getParent();
                if (objParent == null) {
                    objParent = inputDir;
                }

                // 2) Déterminer les chemins de sortie en conservant la structure relative
                Path relative = inputDir.relativize(objPath); // e.g. "subdir/model.obj"
                String baseName = stripExtension(relative.getFileName().toString());

                Path outputObjDir = outputDir.resolve(relative).getParent();
                if (outputObjDir == null) {
                    outputObjDir = outputDir;
                }
                Files.createDirectories(outputObjDir);

                Path outputObjPath = outputObjDir.resolve(baseName + "_atlas.obj");
                Path outputMtlPath = outputObjDir.resolve(baseName + "_atlas.mtl");
                Path outputAtlasPath = outputObjDir.resolve(baseName + "_atlas_diffuse.png");

                // 3) Build atlas from all map_Kd textures
                TextureAtlas atlas = atlasBuilder.buildAtlas(originalModel, objParent, outputAtlasPath);

                // 4) Rewrite UVs & materials for atlas
                ObjModel atlasModel = rewriter.rewriteModelForAtlas(originalModel, atlas);

                // 5) Write new OBJ/MTL
                objWriter.write(atlasModel, outputObjPath, outputMtlPath.getFileName().toString());
                mtlWriter.write(atlasModel.materials(), outputMtlPath);

                long endFile = System.currentTimeMillis();
                System.out.println("[OK]  Output OBJ : " + outputObjPath);
                System.out.println("[OK]  Output MTL : " + outputMtlPath);
                System.out.println("[OK]  Output PNG : " + outputAtlasPath);
                System.out.println("[OK]  Time taken : " + (endFile - startFile) + " ms");
            } catch (Exception e) {
                long endFile = System.currentTimeMillis();
                System.err.println("[ERROR] Failed to process " + objPath + " (" + (endFile - startFile) + " ms)");
                e.printStackTrace(System.err);
            }
        }

        long endTotal = System.currentTimeMillis();
        System.out.println("==================================================");
        System.out.println("[DONE] Batch finished in " + (endTotal - startTotal) + " ms");
    }

    private static String stripExtension(String name) {
        int dot = name.lastIndexOf('.');
        return (dot >= 0) ? name.substring(0, dot) : name;
    }
}