Align sketch with face

[Roy_043]

I am trying to align a sketch with the face of a wall, but have a hard time understanding the Axis and Rotation logic of the sketch. Are there any resources explaining this? Or perhaps some examples?

[jaisejames]

May be useful. Logic is same.

https://forum.freecadweb.org/viewtopic.php?f=22&t=27002

[vocx]

I am trying to align a sketch with the face of a wall, but have a hard time understanding the Axis and Rotation logic of the sketch.

Do you mean the properties that appear in the property editor?

The display is a bit strange to grasp because internally the rotation is handled through quaternions. The best you could do is use Part_Attachment to position the sketch on the face, and let the program automatically calculate the Axis and Angle, and all those values.

See also Placement, and Tutorial_custom_placing_of_windows_and_doors.

[Roy_043]

@jaisejames
Thanks I'll have a go with that example.

@vocx
My goal is to create a macro to automate the steps described in Tutorial_custom_placing_of_windows_and_doors.

[Roy_043]

Ultimately the example was too hard to understand for me. I have used a matrix solution instead:

Code: Select all

import FreeCAD as App
import FreeCADGui as Gui

def WinFix():

    errorMessage = "Selection error: Selection must contain exactly one window and one planar wall face\n"

    selLst = Gui.Selection.getSelectionEx()
    if len(selLst) != 2:
        App.Console.PrintMessage(errorMessage)
        return

    objGui = selLst[0]
    if objGui.Object.Proxy.__module__ == "ArchWindow":
        win    = objGui.Object
        walGui = selLst[1]
        wal    = walGui.Object
    else:
        win    = selLst[1].Object
        walGui = objGui
        wal    = walGui.Object

    if win.Proxy.__module__ != "ArchWindow":
        App.Console.PrintMessage(errorMessage)
        return

    if wal.Proxy.__module__ != "ArchWall":
        App.Console.PrintMessage(errorMessage)
        return

    if not walGui.HasSubObjects:
        App.Console.PrintMessage(errorMessage)
        return

    if len(walGui.SubObjects) != 1:
        App.Console.PrintMessage(errorMessage)
        return

    face = walGui.SubObjects[0]
    # if not type(face.Surface) is Part.Plane:
    if not face.Surface.isPlanar():
        App.Console.PrintMessage(errorMessage)
        return

    ske = win.Base
    if not ske.isDerivedFrom("Sketcher::SketchObject"):
        App.Console.PrintMessage(errorMessage)
        return

    Gui.Selection.clearSelection()

    # https://forum.freecadweb.org/viewtopic.php?t=420
    # Calculate u, v and w vectors and t (=translation) vector.
    w = face.normalAt(0, 0)
    v = App.Vector(0.0, 0.0, 1.0)
    u = v.cross(w)

    # c = face.CenterOfMass
    # t = App.Vector(c.x, c.y, ske.Placement.Base.z)

    b = face.BoundBox
    # Calculate 2 out of 4 possible bottom vectors:
    xA = App.Vector(b.XMax - b.XMin, b.YMax - b.YMin, 0.0).normalize() # BL to TR.
    xB = App.Vector(b.XMax - b.XMin, b.YMin - b.YMax, 0.0).normalize() # TL to BR.

    # Compare u vector with bottom vectors to position t at left edge of face (t.z calculated later):
    if u.isEqual(xA, 1e-6):
        t = App.Vector(b.XMin, b.YMin, 0)
    elif u.isEqual(xA.negative(), 1e-6):
        t = App.Vector(b.XMax, b.YMax, 0)
    elif u.isEqual(xB, 1e-6):
        t = App.Vector(b.XMin, b.YMax, 0)
    else:
        t = App.Vector(b.XMax, b.YMin, 0)

    m = App.Matrix(
    u.x, v.x, w.x, t.x,
    u.y, v.y, w.y, t.y,
    u.z, v.z, w.z, ske.Placement.Base.z + win.Placement.Base.z,
    0.0, 0.0, 0.0, 1.0)

    ske.Placement = App.Placement(m)
    win.Placement = App.Placement() # Reset win placement.
    win.Normal = w.negative()

    oldHosts = win.Hosts
    win.Hosts = [wal]

    # Avoid recomputing whole doc (works if there are no other windows in oldHosts):
    for host in oldHosts:
        host.touch() # Required!
        host.recompute(True)
    ske.recompute(True)
    win.recompute(True)
    wal.recompute(True)

    return

[vocx]

Ultimately the example was too hard to understand for me. I have used a matrix solution instead:

Neither Part nor Arch are used, so you should not import them.

[Roy_043]

Neither Part nor Arch are used, so you should not import them.

Thanks for checking. Fixed!

[vocx]

Thanks for checking. Fixed!

Also, please notice that standard indentation in Python is 4 spaces. Using two spaces makes the code crowded and a bit unreadable. Python relies on whitespace to be readable. I think I've read the standard in Ruby or one of those languages is 2, but that's too little in the opinion of Python.

[Roy_043]

Right, I am still in 'Lisp mode'.
Fixed that + added reset of window placement + tried to improve the recompute.