Source code for boxes.generators.discrack

#!/usr/bin/env python3
# coding: utf-8
# Copyright (C) 2019 chrysn <chrysn@fsfe.org>
#
#   This program is free software: you can redistribute it and/or modify
#   it under the terms of the GNU General Public License as published by
#   the Free Software Foundation, either version 3 of the License, or
#   (at your option) any later version.
#
#   This program 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 General Public License for more details.
#
#   You should have received a copy of the GNU General Public License
#   along with this program.  If not, see <http://www.gnu.org/licenses/>.

from __future__ import division, unicode_literals

from boxes import *
from math import sqrt, pi, sin, cos

def offset_radius_in_square(squareside, angle, outset):
    """From the centre of a square, rotate by an angle relative to the
    vertical, move away from the center (down if angle = 0), and then in a
    right angle until the border of the square. Return the length of that last
    segment.

    Note that for consistency with other boxes.py methods, angle is given in
    degree.

    >>> # Without rotation, it's always half the square length
    >>> offset_radius_in_square(20, 0, 0)
    10.0
    >>> offset_radius_in_square(20, 0, 5)
    10.0
    >>> # Without offset, it's half squre length divided by cos(angle) -- at
    >>> # least before it hits the next wall
    >>> offset_radius_in_square(20, 15, 0) # doctest:+ELLIPSIS
    10.35276...
    >>> offset_radius_in_square(20, 45, 0) # doctest:+ELLIPSIS
    14.1421...
    >>> # Positive angles make the segment initially shorter...
    >>> offset_radius_in_square(20, 5, 10) < 10
    True
    >>> # ... while negative angles make it longer.
    >>> offset_radius_in_square(20, -5, 10) > 10
    True
    """

    if angle <= -90:
        return offset_radius_in_square(squareside, angle + 180, outset)
    if angle > 90:
        return offset_radius_in_square(squareside, angle - 180, outset)

    angle = angle / 180 * pi

    step_right = outset * sin(angle)
    step_down = outset * cos(angle)

    try:
        len_right = (squareside / 2 - step_right) / cos(angle)
    except ZeroDivisionError:
        return squareside / 2

    if angle == 0:
        return len_right
    if angle > 0:
        len_up = (squareside / 2 + step_down) / sin(angle)

        return min(len_up, len_right)
    else: # angle < 0
        len_down = - (squareside / 2 - step_down) / sin(angle)

        return min(len_down, len_right)

[docs]class DiscRack(Boxes): """A rack for storing disk-shaped objects vertically next to each other""" ui_group = "Shelf" def __init__(self): Boxes.__init__(self) self.buildArgParser(sx="20*10") self.argparser.add_argument( "--disc_diameter", action="store", type=float, default=150.0, help="Disc diameter in mm") self.argparser.add_argument( "--disc_thickness", action="store", type=float, default=5.0, help="Thickness of the discs in mm") self.argparser.add_argument( "--lower_factor", action="store", type=float, default=0.75, help="Position of the lower rack grids along the radius") self.argparser.add_argument( "--rear_factor", action="store", type=float, default=0.75, help="Position of the rear rack grids along the radius") self.argparser.add_argument( "--disc_outset", action="store", type=float, default=3.0, help="Additional space kept between the disks and the outbox of the rack") # These can be parameterized, but the default value of pulling them up # to the box front is good enough for so many cases it'd only clutter # the user interface. # # The parameters can be resurfaced when there is something like rare or # advanced settings. ''' self.argparser.add_argument( "--lower_outset", action="store", type=float, default=0.0, help="Space in front of the disk slits (0: automatic)") self.argparser.add_argument( "--rear_outset", action="store", type=float, default=0.0, help="Space above the disk slits (0: automatic)") ''' self.argparser.add_argument( "--angle", action="store", type=float, default=18, help="Backwards slant of the rack") self.addSettingsArgs(edges.FingerJointSettings) def parseArgs(self, *args, **kwargs): Boxes.parseArgs(self, *args, **kwargs) self.lower_outset = self.rear_outset = 0 self.calculate() def calculate(self): self.outer = self.disc_diameter + 2 * self.disc_outset r = self.disc_diameter / 2 # distance between radius line and front (or rear) end of the slit self.lower_halfslit = r * sqrt(1 - self.lower_factor**2) self.rear_halfslit = r * sqrt(1 - self.rear_factor**2) if True: # self.lower_outset == 0: # when lower_outset parameter is re-enabled toplim = offset_radius_in_square(self.outer, self.angle, r * self.lower_factor) # With typical positive angles, the lower surface of board will be limiting bottomlim = offset_radius_in_square(self.outer, self.angle, r * self.lower_factor + self.thickness) self.lower_outset = min(toplim, bottomlim) - self.lower_halfslit if True: # self.rear_outset == 0: # when rear_outset parameter is re-enabled # With typical positive angles, the upper surface of board will be limiting toplim = offset_radius_in_square(self.outer, -self.angle, r * self.rear_factor) bottomlim = offset_radius_in_square(self.outer, -self.angle, r * self.rear_factor + self.thickness) self.rear_outset = min(toplim, bottomlim) - self.rear_halfslit # front outset, space to radius, space to rear part, plus nothing as fingers extend out self.lower_size = self.lower_outset + \ self.lower_halfslit + \ r * self.rear_factor self.rear_size = r * self.lower_factor + \ self.rear_halfslit + \ self.rear_outset self.warn_on_demand() def warn_on_demand(self): warnings = [] # Are the discs supported on the outer ends? def word_thickness(length): if length > 0: return "very thin (%.2g mm at a thickness of %.2g mm)" % ( length, self.thickness) if length < 0: return "absent" if self.rear_outset < self.thickness: warnings.append("Rear upper constraint is %s. Consider increasing" " the disc outset parameter, or move the angle away from 45°." % word_thickness(self.rear_outset) ) if self.lower_outset < self.thickness: warnings.append("Lower front constraint is %s. Consider increasing" " the disc outset parameter, or move the angle away from 45°." % word_thickness(self.lower_outset)) # Are the discs supported where the grids meet? r = self.disc_diameter / 2 inner_lowerdistance = r * self.rear_factor - self.lower_halfslit inner_reardistance = r * self.lower_factor - self.rear_halfslit if inner_lowerdistance < 0 or inner_reardistance < 0: warnings.append("Corner is inside the disc radios, discs would not" " be supported. Consider increasing the factor parameters.") # Won't the type-H edge on the rear side make the whole contraption # wiggle? max_slitlengthplush = offset_radius_in_square( self.outer, self.angle, r * self.rear_factor + self.thickness) slitlengthplush = self.rear_halfslit + self.thickness * ( 1 + \ self.edgesettings['FingerJoint']['edge_width']) if slitlengthplush > max_slitlengthplush: warnings.append("Joint would protrude from lower box edge. Consider" " increasing the the disc outset parameter, or move the" " angle away from 45°.") # Can the discs be removed at all? # Does not need explicit checking, for Thales' theorem tells us that at # the point wher there is barely support in the corner, three contact # points on the circle form just a demicircle and the discs can be # inserted/removed. When we keep the other contact points and move the # slits away from the corner, the disc gets smaller and thus will fit # through the opening that is as wide as the diameter of the largest # possible circle. # Act on warnings if warnings: self.argparser.error("\n".join(warnings)) def sidewall_holes(self): r = self.disc_diameter / 2 self.moveTo(self.outer/2, self.outer/2, -self.angle) # can now move down to paint horizontal lower part, or right to paint # vertical rear part with self.saved_context(): self.moveTo( r * self.rear_factor, -r * self.lower_factor - self.thickness/2, 90) self.fingerHolesAt(0, 0, self.lower_size) with self.saved_context(): self.moveTo( r * self.rear_factor + self.thickness/2, -r * self.lower_factor, 0) self.fingerHolesAt(0, 0, self.rear_size) if self.debug: self.circle(0, 0, self.disc_diameter / 2) def _draw_slits(self, inset, halfslit): total_x = 0 for x in self.sx: center_x = total_x + x / 2 total_x += x self.rectangularHole(inset, center_x, 2 * halfslit, self.disc_thickness) if self.debug: self.ctx.rectangle(inset - halfslit, center_x - x/2, 2 * halfslit, x) def lower_holes(self): r = self.disc_diameter / 2 inset = self.lower_outset + self.lower_halfslit self._draw_slits(inset, self.lower_halfslit) def rear_holes(self): r = self.disc_diameter / 2 inset = r * self.lower_factor self._draw_slits(inset, self.rear_halfslit) def render(self): o = self.outer self.lower_factor = min(self.lower_factor, 0.99) self.rear_factor = min(self.rear_factor, 0.99) self.rectangularWall(o, o, "eeee", move="right", callback=[self.sidewall_holes]) self.rectangularWall(o, o, "eeee", move="right mirror", callback=[self.sidewall_holes]) self.rectangularWall(self.lower_size, sum(self.sx), "fffe", move="right", callback=[self.lower_holes]) self.rectangularWall(self.rear_size, sum(self.sx), "fefh", move="right", callback=[self.rear_holes])