Add Braille example

CadQuery/Examples/Ex029_Braille.py

@@ -0,0 +1,183 @@
+# -*- coding: utf-8 -*-
+
+from __future__ import unicode_literals, division
+
+from collections import namedtuple
+
+import cadquery as cq
+from Helpers import show
+
+# text_lines is a list of text lines.
+# FreeCAD in braille (converted with braille-converter:
+# https://github.com/jpaugh/braille-converter.git).
+text_lines = ['⠠ ⠋ ⠗ ⠑ ⠑ ⠠ ⠉ ⠠ ⠁ ⠠ ⠙']
+# See http://www.tiresias.org/research/reports/braille_cell.htm for examples
+# of braille cell geometry.
+horizontal_interdot = 2.5
+vertical_interdot = 2.5
+horizontal_intercell = 6
+vertical_interline = 10
+dot_height = 0.5
+dot_diameter = 1.3
+
+base_thickness = 1.5
+
+# End of configuration.
+BrailleCellGeometry = namedtuple('BrailleCellGeometry',
+                                 ('horizontal_interdot',
+                                  'vertical_interdot',
+                                  'intercell',
+                                  'interline',
+                                  'dot_height',
+                                  'dot_diameter'))
+
+
+class Point(object):
+    def __init__(self, x, y):
+        self.x = x
+        self.y = y
+
+    def __add__(self, other):
+        return Point(self.x + other.x, self.y + other.y)
+
+    def __len__(self):
+        return 2
+
+    def __getitem__(self, index):
+        return (self.x, self.y)[index]
+
+    def __str__(self):
+        return '({}, {})'.format(self.x, self.y)
+
+
+def brailleToPoints(text, cell_geometry):
+    # Unicode bit pattern (cf. https://en.wikipedia.org/wiki/Braille_Patterns).
+    mask1 = 0b00000001
+    mask2 = 0b00000010
+    mask3 = 0b00000100
+    mask4 = 0b00001000
+    mask5 = 0b00010000
+    mask6 = 0b00100000
+    mask7 = 0b01000000
+    mask8 = 0b10000000
+    masks = (mask1, mask2, mask3, mask4, mask5, mask6, mask7, mask8)
+
+    # Corresponding dot position
+    w = cell_geometry.horizontal_interdot
+    h = cell_geometry.vertical_interdot
+    pos1 = Point(0, 2 * h)
+    pos2 = Point(0, h)
+    pos3 = Point(0, 0)
+    pos4 = Point(w, 2 * h)
+    pos5 = Point(w, h)
+    pos6 = Point(w, 0)
+    pos7 = Point(0, -h)
+    pos8 = Point(w, -h)
+    pos = (pos1, pos2, pos3, pos4, pos5, pos6, pos7, pos8)
+
+    # Braille blank pattern (u'\u2800').
+    blank = '⠀'
+    points = []
+    # Position of dot1 along the x-axis (horizontal).
+    character_origin = 0
+    for c in text:
+        for m, p in zip(masks, pos):
+            delta_to_blank = ord(c) - ord(blank)
+            if (m & delta_to_blank):
+                points.append(p + Point(character_origin, 0))
+        character_origin += cell_geometry.intercell
+    return points
+
+
+def get_plate_height(text_lines, cell_geometry):
+    # cell_geometry.vertical_interdot is also used as space between base
+    # borders and characters.
+    return (2 * cell_geometry.vertical_interdot +
+            2 * cell_geometry.vertical_interdot +
+            (len(text_lines) - 1) * cell_geometry.interline)
+
+
+def get_plate_width(text_lines, cell_geometry):
+    # cell_geometry.horizontal_interdot is also used as space between base
+    # borders and characters.
+    max_len = max([len(t) for t in text_lines])
+    return (2 * cell_geometry.horizontal_interdot +
+            cell_geometry.horizontal_interdot +
+            (max_len - 1) * cell_geometry.intercell)
+
+
+def get_cylinder_radius(cell_geometry):
+    """Return the radius the cylinder should have
+
+    The cylinder have the same radius as the half-sphere make the dots (the
+    hidden and the shown part of the dots).
+    The radius is such that the spherical cap with diameter
+    cell_geometry.dot_diameter has a height of cell_geometry.dot_height.
+    """
+    h = cell_geometry.dot_height
+    r = cell_geometry.dot_diameter / 2
+    return (r ** 2 + h ** 2) / 2 / h
+
+
+def get_base_plate_thickness(plate_thickness, cell_geometry):
+    """Return the height on which the half spheres will sit"""
+    return (plate_thickness +
+            get_cylinder_radius(cell_geometry) -
+            cell_geometry.dot_height)
+
+
+def make_base(text_lines, cell_geometry, plate_thickness):
+    base_width = get_plate_width(text_lines, cell_geometry)
+    base_height = get_plate_height(text_lines, cell_geometry)
+    base_thickness = get_base_plate_thickness(plate_thickness, cell_geometry)
+    base = cq.Workplane('XY').box(base_width, base_height, base_thickness,
+                                  centered=(False, False, False))
+    return base
+
+
+def make_embossed_plate(text_lines, cell_geometry):
+    """Make an embossed plate with dots as spherical caps
+
+    Method:
+        - make a thin plate on which sit cylinders
+        - fillet the upper edge of the cylinders so to get pseudo half-spheres
+        - make the union with a thicker plate so that only the sphere caps stay
+          "visible".
+    """
+    base = make_base(text_lines, cell_geometry, base_thickness)
+
+    dot_pos = []
+    base_width = get_plate_width(text_lines, cell_geometry)
+    base_height = get_plate_height(text_lines, cell_geometry)
+    y = base_height - 3 * cell_geometry.vertical_interdot
+    line_start_pos = Point(cell_geometry.horizontal_interdot, y)
+    for text in text_lines:
+        dots = brailleToPoints(text, cell_geometry)
+        dots = [p + line_start_pos for p in dots]
+        dot_pos += dots
+        line_start_pos += Point(0, -cell_geometry.interline)
+
+    r = get_cylinder_radius(cell_geometry)
+    base = base.faces('>Z').vertices('<XY').workplane() \
+        .pushPoints(dot_pos).circle(r) \
+        .extrude(r)
+    # Make a fillet almost the same radius to get a pseudo spherical cap.
+    base = base.faces('>Z').edges() \
+        .fillet(r - 0.001)
+    hidding_box = cq.Workplane('XY').box(
+        base_width, base_height, base_thickness, centered=(False, False, False))
+    result = hidding_box.union(base)
+    return result
+
+_cell_geometry = BrailleCellGeometry(
+    horizontal_interdot,
+    vertical_interdot,
+    horizontal_intercell,
+    vertical_interline,
+    dot_height,
+    dot_diameter)
+
+if base_thickness < get_cylinder_radius(_cell_geometry):
+    raise ValueError('Base thickness should be at least {}'.format(dot_height))
+
+show(make_embossed_plate(text_lines, _cell_geometry))