Macro Shake Sketch

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Macro Shake Sketch.png Macro Shake Sketch

Description
Shake a sketch in order to discover its unconstrained parts. Enter edit mode for a sketch and launch the macro. The macro will add a random noise on all sketch points. The sketch is then solved, constrained parts will retain their position, free parts will move (But be careful working on a copy of your file because the macro "dismantles all" to display and you may start over). Install through addon manager broken, please see macro wiki page for instruction.

Macro version: 1.2
Last modified: 2021-10-22
FreeCAD version: All
Download: ToolBar Icon
Author: Gaël Ecorchard, heda
Author
Gaël Ecorchard, heda
Download
ToolBar Icon
Links
Macro Version
1.2
Date last modified
2021-10-22
FreeCAD Version(s)
All
Default shortcut
None
See also
None

Description

Shake a sketch in order to discover its unconstrained parts. Enter edit mode for a sketch and launch the macro. The macro will add a random noise on all sketch points. The sketch is then solved, constrained parts will retain their position, free parts will move.

But be careful working on a copy of your file because the macro "dismantles all" to display and you may start over.

Install

Visible in Addon manager, but install is broken. For now only option is to manually install, but you have to take the code from "view source" from this wiki. The full code is there, but it does not render on the wiki.

Script

ToolBar Icon Macro Shake Sketch.png

Macro Shake_Sketch.py

# -*- coding: utf-8 -*-

# FreeCAD macro to shake a sketch in order to discover its unconstrained parts.
#
# A Gaussian noise is introduced in all sketch points and the sketch is then
# solved.
# Beware that the sketch can look different because some constraints have
# several solutions. In this case, just undo.
#
# This file is released under the MIT License.
# Author: Gaël Ecorchard v1.0 & v1.1
# Author: heda v1.2
# Version:
# - 1.2: 2021-10-22
#       * made macro runnable for current versions of fc
#       * added Part.LineSegment
#       * added start info & result dialogue
#       * hides constraints during shake
#       * added simple debug printing
# - 1.1: 2014-10-31
#       * correct import for Part
# - 1.0: 2014-08
#       * first release

# Amplitude of the point displacements.
# The standard deviation of the Gaussian noise is the largest sketch dimension
# multiplied by this factor.
__version__ = '1.2'
displacement_amplitude = 0.1
debug_print = False
title = 'Sketch Shaker Macro (ver: {})'.format(__version__)

# End of configuration.

from random import gauss

from PySide.QtGui import QMessageBox

import FreeCADGui as Gui
from FreeCAD import Base
import Part

print('Running {}'.format(title))

# For each sketch geometry type, map a list of points to move.
g_geom_points = {
    Base.Vector: [1],
    Part.Line: [1, 2],  # first point, last point
    Part.LineSegment: [1, 2],  # first point, last point
    Part.Circle: [0, 3],  # curve, center
    Part.ArcOfCircle: [1, 2, 3],  # first point, last point, center
} # moves bsplines and conics via lines and circles, no op for Part.Points


def dprint(msg, *args):
    if debug_print:
        if args:
            print(msg.format(*args))
        else:
            print(msg)

class BoundingBox:
    xmin = xmax = ymin = ymax = None

    def enlarge_x(self, x):
        if self.xmin is None:
            self.xmin = self.xmax = x
        elif self.xmin > x:
            self.xmin = x
        elif self.xmax < x:
            self.xmax = x

    def enlarge_y(self, y):
        if self.ymin is None:
            self.ymin = self.ymax = y
        elif self.ymin > y:
            self.ymin = y
        elif self.ymax < y:
            self.ymax = y

    def enlarge_point(self, point):
        self.enlarge_x(point.x)
        self.enlarge_y(point.y)

    def enlarge_line(self, line):
        self.enlarge_x(line.StartPoint.x)
        self.enlarge_x(line.EndPoint.x)
        self.enlarge_y(line.StartPoint.y)
        self.enlarge_y(line.EndPoint.y)

    def enlarge_circle(self, circle):
        self.enlarge_x(circle.Center.x - circle.Radius)
        self.enlarge_x(circle.Center.x + circle.Radius)
        self.enlarge_y(circle.Center.y - circle.Radius)
        self.enlarge_y(circle.Center.y + circle.Radius)

    def enlarge_arc_of_circle(self, arc):
        # TODO: correctly compute the arc extrema (cf. toShape().BoundBox)
        self.enlarge_x(arc.Center.x)
        self.enlarge_y(arc.Center.y)


def get_sketch_dims(sketch):
    bbox = BoundingBox()
    for geom in sketch.Geometry:
        if isinstance(geom, Base.Vector):
            bbox.enlarge_point(geom)
        elif isinstance(geom, (Part.Line, Part.LineSegment)):
            bbox.enlarge_line(geom)
        elif isinstance(geom, Part.Circle):
            bbox.enlarge_circle(geom)
        elif isinstance(geom, Part.ArcOfCircle):
            bbox.enlarge_arc_of_circle(geom)
    if None in (bbox.xmin, bbox.ymin):
        dprint('sketch bbox not found')
        return 0, 0
    else:
        dprint('sketch bbox found')
        return bbox.xmax - bbox.xmin, bbox.ymax - bbox.ymin


def add_noise(point, sigma):
    """Add a Gaussian noise with standard deviation sigma"""
    dprint('  x0:{:>9.3f}  y0:{:>9.3f}', point.x, point.y)
    point.x = gauss(point.x, sigma)
    point.y = gauss(point.y, sigma)
    dprint('  xt:{:>9.3f}  yt:{:>9.3f}', point.x, point.y)


def move_points(sketch, geom_index, sigma):
    point_indexes = g_geom_points.get(type(sketch.Geometry[i]), [])
    # Direct access to sketch.Geometry[index] does not work. This would,
    # however prevent repeated recompute.
    # not checked validity of comment for v1.2
    moved = False
    for point_index in point_indexes:
        dprint('---- geo idx [{:>3} ] -- pt idx [{:>3} ] ----',
               geom_index, point_index)
        point = sketch.getPoint(geom_index, point_index)
        add_noise(point, sigma)
        try:
            sketch.movePoint(geom_index, point_index, point)
        except ValueError as e:
            dprint(repr(e))
        new_pos = sketch.getPoint(geom_index, point_index)
        test = point.isEqual(new_pos, 0)
        dprint('  did it move? {}', test)
        if test: moved = True
    return moved

def toggle_constraints(sketch, toggle):
    for cid in toggle:
        sketch.toggleVirtualSpace(cid)
    

view_provider = Gui.activeDocument().getInEdit()

shake_it = False
if not view_provider:
    msg = 'A sketch needs to be in edit to be shaken.'
    print(msg)
    _ = QMessageBox.information(None, title, msg)
else:
    sketch = view_provider.Object
    if sketch.TypeId == 'Sketcher::SketchObject':
        sketch.recompute() # ensure update
        to_virtual = [cid for cid, cts in enumerate(sketch.Constraints)
                      if cts.InVirtualSpace]
        sketch_span = get_sketch_dims(sketch)
        sigma = max(sketch_span) * displacement_amplitude
        dprint('sketch span: dx:{:>9.3f} dy:{:>9.3f}', *sketch_span)
        dprint('sigma for gauss-dist: {:.3f}', sigma)
        toggle_constraints(sketch, to_virtual)
        msg = ('Shake sketch will deform the loose parts of the sketch.\n'
               'The deformation cannot be undone.\n'
               'If that is not desired, click Cancel,\n'
               'and run the macro on a copy of the sketch.\n\n'
               'Visibility of constraints has been toggled.\n'
               'Visibility of constraints is restored'
               ' after shaking the sketch.')
        reply = QMessageBox.information(None, title, msg,
                                        QMessageBox.Ok