# 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
#   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

"""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
10.0
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")
"--disc_diameter", action="store", type=float, default=150.0,
help="Disc diameter in mm")
"--disc_thickness", action="store", type=float, default=5.0,
help="Thickness of the discs in mm")

"--lower_factor", action="store", type=float, default=0.75,
help="Position of the lower rack grids along the radius")
"--rear_factor", action="store", type=float, default=0.75,
help="Position of the rear rack grids along the radius")

"--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
'''
"--lower_outset", action="store", type=float, default=0.0,
help="Space in front of the disk slits (0: automatic)")
"--rear_outset", action="store", type=float, default=0.0,
help="Space above the disk slits (0: automatic)")
'''

"--angle", action="store", type=float, default=18,
help="Backwards slant of the rack")

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?

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])
```