hinge.ko

##    Geometry header    ##
[(koko.prims.points.Point, {'y': '3.68116250962', 'x': '6.6241576341', 'name': 'corner'}),(koko.prims.points.Point, {'y': 'corner.y', 'x': '3.96428776181', 'name': 'border'}),(koko.prims.utils.Slider, {'name': 'esw_slider', 'min': '0', 'max': '0.5', 'value': '0.12974617506', 'y': '2.36389504454', 'x': '10.2595197251', 'size': '5'}),(koko.prims.utils.Slider, {'name': 'esl_slider', 'min': '1', 'max': '5', 'value': '1.4', 'y': '0.128180535766', 'x': '10.379580192', 'size': '5'}),(koko.prims.utils.Slider, {'name': 'wt_slider', 'min': '0', 'max': '0.5', 'value': '0.207806851754', 'y': '-2.07664232583', 'x': '10.4804981458', 'size': '5'})]
##    End of geometry header    ##
"""
examples/hinge.ko

A response living hinge.  Drag the corners or adjust the sliders
to change its size and other parameters.

Based on a design by Terrence J. Fagan
(http://terencefagan.wordpress.com/) posted at
http://fabacademy.org/archives/2014/tutorials/LivingHingeinKokopelli.html

"""
from koko.lib.shapes import *
import operator
import math

# ##############################################################
# Driving parameters:
# These values are taken from UI handles; click and drag the
# sliders and points to modify the hinge.
esw =  esw_slider.value  # Empty space thickness
esl =  esl_slider.value  # Empty space length
wt  =  wt_slider.value   # Web thickness
w   =  corner.x          # Half of sheet width
h   =  corner.y          # Half of sheet height
# ##############################################################

# Calculate how many cutouts we need in the x and y direction,
# based on living hinge parameters and the sheet size
x_count = int(math.ceil((border.x - esw/2 - wt) / (esw + wt)))
y_count = int(math.ceil(h / (esl + 2*esw + wt)))

# This is the basic shape for the cutout:
# It's a rectangle with circular caps at the top and bottom
es = (rectangle(-esw/2, esw/2, -esl/2, esl/2) +
      circle(0,esl/2,esw/2) + circle(0,-esl/2,esw/2))

# Tile the cutout object in the vertical direction
es = reduce(operator.add,
        [move(es, 0, i*(esl + esw + wt))
         for i in range(-y_count, y_count + 1)])

# Tile horizontally with interleaved offset cutouts.
print x_count
cutout = reduce(operator.add,
        [move(es, i * (esw + wt), 0)
         for i in range(-x_count, x_count + 1, 2)] +
        [move(es, i * (esw + wt), esl/2 + esw)
         for i in range(-x_count + 1, x_count, 2)])

# Finally, subtract the cutouts from the hinge shape
cad.shape = rectangle(-w,w,-h,h) - cutout