TDEdgeIntersection.FCMacro

"""
This Macro is intended to be used in the TechDraw Workbench,
to find the intersection point of two Edges inside a DrawViewPart.

Select two Egdes and run the Macro. The cosmetic vertex will be created
at the intersection point.
"""

__Name__ = 'TDEdgeIntersection'
__Comment__ = 'Inserts a cosmetic vertex at the position where two lines intersect'
__Author__ = 'Sebastian Bachmann'
__Version__ = '1.0'
__Date__ = '2020-05-07'
__License__ = 'MIT'
__Web__ = 'https://github.com/reox/FreeCAD_Macros'
__Wiki__ = ''
__Icon__ = 'icons/EdgeIntersection.svg'
__Help__ = 'Select two straight lines and run the macro'
__Status__ = 'Stable'
__Requires__ = '>=0.19.20943; py3 only'
__Communication__ = 'https://github.com/reox/FreeCAD_Macros/issues'


# Copyright (c) 2019, Sebastian Bachmann <hello@reox.at>
#
# Permission is hereby granted, free of charge, to any person obtaining a copy of
# this software and associated documentation files (the "Software"), to deal in
# the Software without restriction, including without limitation the rights to
# use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
# the Software, and to permit persons to whom the Software is furnished to do so,
# subject to the following conditions:
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
# FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
# COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
# IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.


import numpy as np
from PySide.QtGui import QMessageBox
from PySide import QtCore


def msg(title, message):
    diag = QMessageBox(QMessageBox.Warning, title, message)
    diag.setWindowModality(QtCore.Qt.ApplicationModal)
    diag.exec_()


def find_intersection():
    """
    Finds the intersection point of two edges
    And creates a cosmetic vertex there
    """
    # Get the current view:
    cur_view = Gui.Selection.getSelectionEx()[0].Object

    if not cur_view.isDerivedFrom("TechDraw::DrawViewPart"):
        msg("Wrong Selection", "Must select Edges of DrawViewPart!")
        return

    # Get the names of the selected edges:
    elem = Gui.Selection.getSelectionEx()[0].SubElementNames

    if not all(map(lambda x: x.startswith('Edge'), elem)) or len(elem) != 2:
        msg("Wrong Selection", "You have not selected two edges!")
        return

    try:
        indices = map(lambda x: int(x.replace('Edge', '')), elem)
    except ValueError as e:
        msg("Something is wrong", "Can not parse Edge indices: {}".format(e))
        return

    (p, q), (r, s) = list(map(lambda i: (i[0].Point, i[1].Point), map(lambda a:
        cur_view.getEdgeByIndex(a).Vertexes, indices)))

    # Want to solve: p + t(q - p) = r + v(s - r)
    # t and v are costants, p,q,r,s are vectors
    a = np.array([[q.x - p.x, -s.x + r.x], [q.y - p.y, -s.y + r.y]])
    b = np.array([r.x - p.x, r.y - p.y])
    try:
        t, v = np.linalg.solve(a, b)
    except np.linalg.LinAlgError:
        # usually singular matrix -> det(a) = 0 -> parallel lines
        msg("Singular Matrix", "The lines are probably parallel, no intersection possible!")
    else:
        x = p.x + t * (q.x - p.x)
        y = r.y + v * (s.y - r.y)
        res = FreeCAD.Vector(x, y, 0)

        # Add the Vertex
        cur_view.makeCosmeticVertex(res)

    # Recompute
    App.activeDocument().recompute(None,True,True)


if __name__ == "__main__":
    find_intersection()