wang.py

#!/usr/bin/env python3

# Nicolas Seriot
# 2023-03-31
# https://gist.github.com/nst/f9269ff6b8cadd619b9c3058868da70f

# https://seriot.ch/visualization/wang_pipes.png

import random
import cairo

random.seed(0)

TS = 32

W = 16
H = 16

# sprite structure
# http://www.cr31.co.uk/stagecast/wang/intro.html
# http://www.cr31.co.uk/stagecast/wang/tiles_e.html

SPRITE_POS = [(0,3), # 0
              (0,2), # 1
              (1,3), # 2
              (1,2), # 3
              (0,0), # 4
              (0,1), # 5
              (1,0), # 6
              (1,1), # 7
              (3,3), # 8
              (3,2), # 9
              (2,3), # 10
              (2,2), # 11
              (3,0), # 12
              (3,1), # 13
              (2,0), # 14
              (2,1)] # 15

def draw_tile(c, img, n):

    assert(n in range(0,16))
    
    x, y = SPRITE_POS[n]
    
    c.save()
    c.translate(TS*-x, TS*-y)
    c.rectangle(TS*x, TS*y, TS, TS)
    c.clip()
    c.set_source_surface(img, 0, 0)
    c.paint()
    c.restore()

def fill_board(width, height, clean_edges):

    # bits 1111 WSEN

    m = [[0 for x in range(width)] for y in range(height)] 
    
    for y in range(height):
        for x in range(width):
            
            t = random.randint(0,15)
            
            # propagate E -> W
            
            if x > 0:
                n = m[y][x-1]
                
                t = (t & 0b0111) | ((n & 0b0010) << 2)

            # propagate S -> N
            
            if y > 0:
                n = m[y-1][x]
                
                t = (t & 0b1110) | ((n & 0b0100) >> 2)
            
            if clean_edges:
                
                if x == 0:
                    t &= 0b0111
                
                if x == (width-1):
                    t &= 0b1101
    
                if y == 0:
                    t &= 0b1110
                
                if y == (height-1):
                    t &= 0b1001
                        
            m[y][x] = t
    
    return m

def draw_board(m, sprite_name, board_name):

    surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, TS*W, TS*H)
    c = cairo.Context(surface)
    
    c.set_source_rgb(1,1,1)
    c.paint()
    
    sprite = cairo.ImageSurface.create_from_png(sprite_name)
    
    assert(sprite.get_width() == 128)
    assert(sprite.get_height() == 128)
    
    for y in range(H):
        for x in range(W):
            n = m[y][x]
            
            c.save()
            c.translate(TS*x, TS*y)        
            draw_tile(c, sprite, n)
            c.restore()
    
    surface.write_to_png(board_name)

def main():

    m = fill_board(width=W, height=H, clean_edges=False)
    
    for l in m:
        print(*[("{0:04b}".format(t)) for t in l])

    draw_board(m, "wang2e.png", "wang.png")
#    draw_board("pipe1.png", "wang.png")

if __name__ == "__main__":
    main()