Cellular automata

cell.py

from collections import defaultdict
import sys

from svg import *

def log(*a, **k):
    print(*a, **k, file=sys.stderr)

ROWS = 16

STOP_AFTER = ROWS

COLS = ROWS*2-1
BOXSIZE = 16

HEADER_HEIGHT = BOXSIZE * ROWS * (3/4)

NOM_WIDTH = COLS * BOXSIZE + 1 + 20
NOM_HEIGHT = NOM_WIDTH // 2 ** 0.5
NOM_YBIAS = NOM_HEIGHT - (ROWS * BOXSIZE + 10)

IMG_HEIGHT = 1024
IMG_WIDTH = IMG_HEIGHT / NOM_HEIGHT * NOM_WIDTH

RULE_GAP = 2
RULE_MGAP = 3
RULE_MARGIN = 2

if len(sys.argv) > 1:
    rule = int(sys.argv[1])
else:
    rule = 30

# Basic header
svg_header()
svg_open(width=IMG_WIDTH, height=IMG_HEIGHT,
         x_bias=-(NOM_WIDTH-1)/2-1, y_bias=-NOM_YBIAS+12,
         xw=NOM_WIDTH+1, yh=NOM_HEIGHT+1)

def draw_box(x, y, value=None, scale=1):
    svg_rect((x*scale, y*scale), scale*BOXSIZE, scale*BOXSIZE,
             fill="black" if value else "white",
             stroke="grey", stroke_width=scale)

def draw_cell(row, col, value=None, scale=1):
    draw_box(BOXSIZE*(col-0.5), BOXSIZE*row,
             value=value, scale=scale)

#def draw_rule(x, y, n):
#    scale = COLS / (4*3 + 3*RULE_GAP + 2*RULE_MARGIN)
#    draw_box((x - 1.5)*BOXSIZE, y * BOXSIZE      , n & 4 != 0          , scale)
#    draw_box((x - 0.5)*BOXSIZE, y * BOXSIZE      , n & 2 != 0          , scale)
#    draw_box((x + 0.5)*BOXSIZE, y * BOXSIZE      , n & 1 != 0          , scale)
#    draw_box((x - 0.5)*BOXSIZE, (y + 1) * BOXSIZE, rule & (1 << n) != 0, scale)
#
#draw_rule(-(3 + RULE_MGAP)/2 - 3 - RULE_GAP, -7, 7)
#draw_rule(-(3 + RULE_MGAP)/2               , -7, 6)
#draw_rule( (3 + RULE_MGAP)/2               , -7, 5)
#draw_rule( (3 + RULE_MGAP)/2 + 3 + RULE_GAP, -7, 4)
#draw_rule(-(3 + RULE_MGAP)/2 - 3 - RULE_GAP, -3, 3)
#draw_rule(-(3 + RULE_MGAP)/2               , -3, 2)
#draw_rule( (3 + RULE_MGAP)/2               , -3, 1)
#draw_rule( (3 + RULE_MGAP)/2 + 3 + RULE_GAP, -3, 0)

def draw_rule(row, col, n):
    draw_cell(row, col - 1, n & 4 != 0)
    draw_cell(row, col, n & 2 != 0)
    draw_cell(row, col + 1, n & 1 != 0)
    draw_cell(row + 1, col, rule & (1 << n) != 0)

draw_rule(-4, -14, 7)
draw_rule(-4, -10, 6)
draw_rule(-4,  -6, 5)
draw_rule(-4,  -2, 4)
draw_rule(-4,   2, 3)
draw_rule(-4,   6, 2)
draw_rule(-4,  10, 1)
draw_rule(-4,  14, 0)

cells = defaultdict(lambda: False)
cells[(0,0)] = True
draw_cell(0, 0, cells[(0,0)])


for j in range(1, ROWS):
    if j >= STOP_AFTER:
        for i in range(-j, j+1):
            draw_cell(j, i, False)
        continue
    for i in range(-j, j+1):
        prev =  4 * cells[(j-1, i-1)]
        prev += 2 * cells[(j-1, i  )]
        prev += 1 * cells[(j-1, i+1)]
        cells[(j,i)] = rule & (1 << prev) != 0
        draw_cell(j, i, cells[(j,i)])

# Footer
svg_close()

Makefile

.PHONY: test
test: 027.png

.PHONY: all
all:
	$(MAKE) -j 4 $$(for i in $$(seq -w 0 255); do echo -n "$$i.png "; done)

%.png: %.svg
	convert $^ $@

%.svg: cell.py svg.py
	python3 $< $* > $@

.PHONY: clean
clean:
	rm -f *.png *.svg *.mp4

svg.py

def xml(tag, _xml_tag_is_a_singleton=True, **options):
    s = f'<{tag}'
    kw_attrib = lambda x: x.replace('_', '-')
    if options:
        s += ' '
        s += ' '.join(f'{kw_attrib(k)}="{str(v)}"' for k, v in options.items())
    if _xml_tag_is_a_singleton:
        s += ' />'
    else:
        s += '>'
    print(s)

def xml_open(*args, **kwargs):
    xml(*args, **kwargs, _xml_tag_is_a_singleton=False)

def xml_close(tag):
    print(f'</{tag}>')

def svg_header():
    '<?xml version="1.0" encoding="UTF-8" standalone="no"?>'

def svg_open(width, height, x_bias, y_bias, xw, yh):
    vb = f'{x_bias} {y_bias} {xw} {yh}'
    ns = 'http://www.w3.org/2000/svg'
    xml_open('svg', width=width, height=height, viewBox=vb, xmlns=ns)

def svg_close():
    xml_close('svg')

def svg_poly(*points, **opts):
    point_str = ' '.join(f'{x},{y}' for x, y in points)
    xml('polyline', points=point_str, **opts)

def svg_circle(point, radius, **opts):
    xml('circle', cx=point[0], cy=point[1], r=radius, **opts)

def svg_line(p1, p2, **opts):
    xml('line', x1=p1[0], y1=p1[1], x2=p2[0], y2=p2[1], **opts)

def svg_rect(p, width, height, x_radius=0, y_radius=0, **opts):
    xml('rect', x=p[0], y=p[1], width=width, height=height,
              rx=x_radius, ry=y_radius, **opts)