import bpy, bmesh, struct


def write_some_data(context, filepath, use_some_setting):
    f = open(filepath, "wb")
    
    bm = bmesh.new()
    bm.from_object(context.active_object, context.scene)
    bmesh.ops.triangulate(bm, faces = bm.faces)
    
    for face in bm.faces:
        for loop in face.loops:
            f.write(struct.pack("3f", loop.vert.co.x, loop.vert.co.z, -loop.vert.co.y))
    
    f.close()

    return {'FINISHED'}


# ExportHelper is a helper class, defines filename and
# invoke() function which calls the file selector.
from bpy_extras.io_utils import ExportHelper
from bpy.props import StringProperty, BoolProperty, EnumProperty
from bpy.types import Operator


class ExportSomeData(Operator, ExportHelper):
    """This appears in the tooltip of the operator and in the generated docs"""
    bl_idname = "export_trimesh.some_data"  # important since its how bpy.ops.import_test.some_data is constructed
    bl_label = "Export Triangle Mesh"

    # ExportHelper mixin class uses this
    filename_ext = ".phys"

    filter_glob = StringProperty(
            default="*.phys",
            options={'HIDDEN'},
            maxlen=255,  # Max internal buffer length, longer would be clamped.
            )

    # List of operator properties, the attributes will be assigned
    # to the class instance from the operator settings before calling.
    use_setting = BoolProperty(
            name="Example Boolean",
            description="Example Tooltip",
            default=True,
            )

    type = EnumProperty(
            name="Example Enum",
            description="Choose between two items",
            items=(('OPT_A', "First Option", "Description one"),
                   ('OPT_B', "Second Option", "Description two")),
            default='OPT_A',
            )

    def execute(self, context):
        return write_some_data(context, self.filepath, self.use_setting)


# Only needed if you want to add into a dynamic menu
def menu_func_export(self, context):
    self.layout.operator(ExportSomeData.bl_idname, text="Export Raw Triangle Mesh")


def register():
    bpy.utils.register_class(ExportSomeData)
    bpy.types.INFO_MT_file_export.append(menu_func_export)


def unregister():
    bpy.utils.unregister_class(ExportSomeData)
    bpy.types.INFO_MT_file_export.remove(menu_func_export)


if __name__ == "__main__":
    register()