core_geometry_recognize_feature.py

##Copyright 2017-2019 Thomas Paviot (tpaviot@gmail.com)
##
##This file is part of pythonOCC.
##
##pythonOCC is free software: you can redistribute it and/or modify
##it under the terms of the GNU Lesser General Public License as published by
##the Free Software Foundation, either version 3 of the License, or
##(at your option) any later version.
##
##pythonOCC is distributed in the hope that it will be useful,
##but WITHOUT ANY WARRANTY; without even the implied warranty of
##MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
##GNU Lesser General Public License for more details.
##
##You should have received a copy of the GNU Lesser General Public License
##along with pythonOCC.  If not, see <http://www.gnu.org/licenses/>.

""" Loads a STEP file and identify geometrical nature of each face
(cylindrical face, planar etc.)
See github issue https://github.com/tpaviot/pythonocc-core/issues/470
Two options in this example:
1. Click any planar or cylindrical face from the 3d window. They will
be identified as known surfaces, their properties displayed in the
console
2. A batch mode : click the menu button. All the faces will be traversed
and analyzed
"""

from __future__ import print_function

import sys

from OCC.Core.GeomAbs import GeomAbs_Plane, GeomAbs_Cylinder, GeomAbs_BSplineSurface
from OCC.Core.BRepAdaptor import BRepAdaptor_Surface
from OCC.Core.TopoDS import TopoDS_Face
from OCC.Display.SimpleGui import init_display
from OCC.Extend.DataExchange import read_step_file
from OCC.Extend.TopologyUtils import TopologyExplorer


def recognize_face(a_face):
    """Takes a TopoDS shape and tries to identify its nature
    whether it is a plane a cylinder a torus etc.
    if a plane, returns the normal
    if a cylinder, returns the radius
    """
    if type(a_face) is not TopoDS_Face:
        print("Please hit the 'G' key to switch to face selection mode")
        return False
    surf = BRepAdaptor_Surface(a_face, True)
    surf_type = surf.GetType()
    if surf_type == GeomAbs_Plane:
        print("Identified Plane Geometry")
        # look for the properties of the plane
        # first get the related gp_Pln
        gp_pln = surf.Plane()
        location = gp_pln.Location()  # a point of the plane
        normal = gp_pln.Axis().Direction()  # the plane normal
        # then export location and normal to the console output
        print(
            "--> Location (global coordinates)",
            location.X(),
            location.Y(),
            location.Z(),
        )
        print("--> Normal (global coordinates)", normal.X(), normal.Y(), normal.Z())
    elif surf_type == GeomAbs_Cylinder:
        print("Identified Cylinder Geometry")
        # look for the properties of the cylinder
        # first get the related gp_Cyl
        gp_cyl = surf.Cylinder()
        location = gp_cyl.Location()  # a point of the axis
        axis = gp_cyl.Axis().Direction()  # the cylinder axis
        # then export location and normal to the console output
        print(
            "--> Location (global coordinates)",
            location.X(),
            location.Y(),
            location.Z(),
        )
        print("--> Axis (global coordinates)", axis.X(), axis.Y(), axis.Z())
    elif surf_type == GeomAbs_BSplineSurface:
        print("Identified BSplineSurface Geometry")
        # gp_bsrf = surf.Surface()
        # degree = gp_bsrf.NbUKnots()
        # TODO use a model that provided BSplineSurfaces, as1_pe_203.stp only contains
        # planes and cylinders
    else:
        # TODO there are plenty other type that can be checked
        # see documentation for the BRepAdaptor class
        # https://www.opencascade.com/doc/occt-6.9.1/refman/html/class_b_rep_adaptor___surface.html
        print(surf_type, "recognition not implemented")


def recognize_clicked(shp, *kwargs):
    """This is the function called every time
    a face is clicked in the 3d view
    """
    for shape in shp:  # this should be a TopoDS_Face TODO check it is
        print("Face selected: ", shape)
        recognize_face(shape)


def recognize_batch(event=None):
    """Menu item : process all the faces of a single shape"""
    # loop over faces only
    for face in TopologyExplorer(shp).faces():
        # call the recognition function
        recognize_face(face)


def exit(event=None):
    sys.exit()


if __name__ == "__main__":
    display, start_display, add_menu, add_function_to_menu = init_display()
    display.SetSelectionModeFace()  # switch to Face selection mode
    display.register_select_callback(recognize_clicked)
    # first loads the STEP file and display
    shp = read_step_file("../assets/models/as1_pe_203.stp")
    display.DisplayShape(shp, update=True)
    add_menu("recognition")
    add_function_to_menu("recognition", recognize_batch)
    start_display()