Today I show you how to make Voronoi diagram using python.
I use this to make textures for underwater.
This is just one example. But you can improve to control all cells of voronoi diagram.
The theory say:
In mathematics, a Voronoi diagram is a special kind of decomposition of a metric space, determined by distances to a specified family of objects (subsets) in the space. These objects are usually called the sites or the generators...Source : wikipedia.
I used the euclidean distance to make the Voronoi diagram because it's the most familiar case.
About wikipedia - Euclidean_distance: In mathematics, the Euclidean distance or Euclidean metric is the "ordinary" distance between two points that one would measure with a ruler, and is given by the Pythagorean formula...
My python script use the next python modules:
PIL - this allow me to use image functions.
random - this module give me... random numbers.
math - some math functions.
Let's see the source code :
from PIL import Image
import random
import math
Now I make the function named gen_voronoi.
This take the height and width of the output image and the number of cells.
The function has some random variables for red , green , blue - nr,ng,nb.
The function hypot is not accessible directly so we need to import math module and using math static object.
The return value is the Euclidean norm : sqrt(x*x + y*y).
def gen_voronoi(w, h, cells):
image = Image.new("RGB", (w, h))
putpixel = image.putpixel
img_x, img_y = image.size
nx = []
ny = []
nr = []
ng = []
nb = []
for i in range(cells):
nx.append(random.randrange(img_x))
ny.append(random.randrange(img_y))
nr.append(random.randrange(256))
ng.append(random.randrange(256))
nb.append(random.randrange(256))
for y in range(img_y):
for x in range(img_x):
dmin = math.hypot(img_x-1, img_y-1)
j = -1
for i in range(cells):
d = math.hypot(nx[i]-x, ny[i]-y)
if d < dmin:
dmin = d
j = i
putpixel((x, y), (nr[j], ng[j], nb[j]))
image.save("output.png", "PNG")
image.show()
Use the function to make the output.png image.
gen_voronoi(200, 200, 55)
The result is :
