[1.12.2] Render .obj and .mtl file

public class LongSword extends ItemSword {
    public LongSword(String name, ToolMaterial material) {
        super(material);
        setRegistryName(name);
        setUnlocalizedName(name);
        setCreativeTab(Main.LevWeapon);
    }
}

public class ItemsRegister {
  
    public static ToolMaterial LongSwordMaterial = EnumHelper.addToolMaterial("LongSwordMaterial", 2, 256, 50.0F, 2.0F, 12);
  
    public static ItemSword long_sword = new LongSword("long_sword", LongSwordMaterial);
  
    public static void register() {
        setRegister(long_sword);
    }
  
    @SideOnly(Side.CLIENT)
    public static void registerRender() {
        setRender(long_sword);
    }
  
    private static void setRegister(Item item) {
        ForgeRegistries.ITEMS.register(item);
    }
  
    @SideOnly(Side.CLIENT)
    private static void setRender(Item item) {
        Minecraft.getMinecraft().getRenderItem().getItemModelMesher().register(item, 0, new ModelResourceLocation(item.getRegistryName(), "inventory"));

    }
}

public class ClientProxy extends CommonProxy {

    public void registerModel(Item item) {
        ModelLoader.setCustomModelResourceLocation(item, 0, new ModelResourceLocation(item.getRegistryName(), "inventory"));
    }

    @Override
    public void preInit(FMLPreInitializationEvent event) {
        OBJLoader.INSTANCE.addDomain(Main.MODID);
        registerModel(ItemsRegister.long_sword);
        super.preInit(event);
    }

    @Override
    public void init(FMLInitializationEvent event) {
        ItemsRegister.registerRender();
        super.init(event);
    }

    @Override
    public void postInit(FMLPostInitializationEvent event) {
        super.postInit(event);
    }
}

{
  "forge_marker": 1,
  "defaults": {
    "model": "leviathan:long_sword.obj"
  },
  "variants": {
    "inventory": [
      {
        "transform": {
          "thirdperson_lefthand": {
            "rotation": [ { "x": -90 }, { "y": 0 }, { "z": 0 } ],
            "translation": [ 0, -0.1, 0.1 ],
            "scale": 1.00
          },
          "thirdperson_righthand": {
            "rotation": [ { "x": -90 }, { "y": 0 }, { "z": 0 } ],
            "translation": [ 0, -0.1, 0.1 ],
            "scale": 1.00
          },
          "gui": {
            "rotation": [ { "x": -90 }, { "y": 0 }, { "z": -0 } ],
            "translation": [ -0.2, -0.2, 0 ],
            "scale": 1.00
          },
          "firstperson_righthand": {
            "rotation": [ { "x": -90 }, { "y": 0 }, { "z": 0 } ],
            "translation": [ 0, -0.1, 0 ],
            "scale": 1.00
          },
          "firstperson_lefthand": {
            "rotation": [ { "x": -90 }, { "y": 0 }, { "z": 0 } ],
            "translation": [ 0, -0.1, 0 ],
            "scale": 1.00
          },
          "ground": {
            "rotation": [ { "x": -90 }, { "y": 0 }, { "z": 0 } ],
            "scale": 1.00
          }
        }
      }
    ]
  }
}

newmtl Garda
Ns 96.078431
Ka 1.000000 1.000000 1.000000
Kd 0.640000 0.640000 0.640000
Ks 0.000000 0.000000 0.000000
Ke 0.000000 0.000000 0.000000
Ni 1.000000
d 1.000000
illum 1
map_Bump leviathan:textures/items/models/nmap_long_sword
map_Ka leviathan:textures/items/models/aomap_long_sword
map_Kd leviathan:textures/items/models/cycmap_long_sword

newmtl Leswie
Ns 96.078431
Ka 1.000000 1.000000 1.000000
Kd 0.640000 0.640000 0.640000
Ks 0.000000 0.000000 0.000000
Ke 0.000000 0.000000 0.000000
Ni 1.000000
d 1.000000
illum 1
map_Bump leviathan:textures/items/models/nmap_long_sword
map_Ka leviathan:textures/items/models/aomap_long_sword
map_Kd leviathan:textures/items/models/cycmap_long_sword

newmtl Ruka
Ns 96.078431
Ka 1.000000 1.000000 1.000000
Kd 0.640000 0.640000 0.640000
Ks 0.500000 0.500000 0.500000
Ke 0.000000 0.000000 0.000000
Ni 1.000000
d 1.000000
illum 2