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#!/usr/bin/python3
r'''Generate a .fig file with a chessboard with a given geometry
SYNOPSIS
./generate-chessboard-fig.py 10 14 > board-10-14.fig
fig2dev -L pdf board-10-14.fig > board-10-14.pdf
'''
import sys
import argparse
import re
import os
def parse_args():
parser = \
argparse.ArgumentParser(description = __doc__,
formatter_class=argparse.RawDescriptionHelpFormatter)
parser.add_argument('--blobs',
action = 'store_true',
help='''If given, we generate a grid of circles, not a
chessboard''')
parser.add_argument('--circle-radius-cells',
type=float,
default = 0.2,
help='''Applies only if --blobs. Specifies the radius of
each circle, in the units of grid spacing: radius == 0.5
would create circles that are large enough such that
adjacent ones touch.''')
parser.add_argument('Wcorners',
type=int,
help='''The number of chessboard corners in the
horizontal direction''')
parser.add_argument('Hcorners',
type=int,
help='''The number of chessboard corners in the vertical
direction''')
args = parser.parse_args()
return args
args = parse_args()
import numpy as np
import numpysane as nps
# The fig format is documented in many places. For instance:
# https://web.archive.org/web/20070920204655/http://epb.lbl.gov/xfig/fig-format.html
#
# Here I simply took the chessboards I drew in xfig, and extended those .fig
# files using this script. The header and chessboard-square definitions come
# directly from the .fig files I made in xfig
header = fr'''#FIG 3.2 Produced by the mrgingham chessboard generator: {sys.argv[0]}
Portrait
Center
Metric
Letter
100.00
Single
-2
1200 2'''
# Arbitrary units. fig2dev appears to compute the bounding box in integer units,
# so if this is too small, the bounding box will be off
square_size = 1000
def black_cell(x,y, *,
double_width = False,
double_height = False):
X0 = (x+0)*square_size
X1 = (x+1)*square_size
Y0 = (y+0)*square_size
Y1 = (y+1)*square_size
if double_width:
X1 += square_size
if double_height:
Y1 += square_size
print("2 2 0 0 0 0 50 -1 20 0.000 0 0 -1 0 0 5")
print(f" {X0} {Y0} {X1} {Y0} {X1} {Y1} {X0} {Y1} {X0} {Y0}")
def black_circle(x,y,R):
'''Units of all x,y is "cells". Units of R is "fig units"'''
X = x * square_size
Y = y * square_size
print(f"1 3 0 0 0 0 50 -1 20 0 1 0 {X} {Y} {R} {R} {X} {Y} {X+R} {Y}")
Wcells = args.Wcorners + 3
Hcells = args.Hcorners + 3
print(header)
if not args.blobs:
if (args.Wcorners // 2) * 2 != args.Wcorners or \
(args.Hcorners // 2) * 2 != args.Hcorners:
print("Wcorners and Hcorners are assumed to be even",
file = sys.stderr)
sys.exit(1)
# top/bottom edges
for y in (0,Hcells-2):
for x in range(2,Wcells-2,2):
black_cell(x,y,
double_height = True)
# left/right edges
for x in (0,Wcells-2):
for y in range(2,Hcells-2,2):
black_cell(x,y,
double_width = True)
# middle
for y in range(2,Hcells-2,2):
for x in range(3,Wcells-2,2):
black_cell(x,y)
for y in range(3,Hcells-2,2):
for x in range(2,Wcells-2,2):
black_cell(x,y)
else:
R = int(round(square_size * args.circle_radius_cells))
for y in range(0,args.Hcorners):
for x in range(0,args.Wcorners):
black_circle(x,y,R)
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