from __future__ import division
from visual import *
from random import *
import pickle
# Bruce Sherwood, June 2006; use this any way you like.
# This program generates a wood-like surface by "line integral convolution"
# in which you start from an array of random values, then average them
# along lines (or curves) for a certain distance, so that locations along
# a curve have similar values, giving a streaked appearance. This simple program
# only handles straight stream lines.

# For more information, google "line integral convolution".
# There also exists a much more efficient "fast line integral convolution".

M = 256 # texture must be 2**M by 2**N
N = M
filename = 'wood%ilum.vpt' % M
print 'Texture file name: '+filename
slope = 0.5 # use negative slope in calculations below; texture y gets inverted
write = 1 # 1 to create a texture file, 0 to read existing texture file
if write: 
    t = zeros([M,N], float) # numpy array; elements are random floats 0 to 1
    u = zeros([M,N], ubyte) # numpy array; elements are integers 0 to 255
    for y in range(M):
        for x in range(N):
            t[y][x] = random() # t array contains random numbers

    halfrange = int(0.1*M) # average 2*halfrange+1 points along stream line
    for y in range(M):
        for x in range(N):
            avg = 0
            for s in range(-halfrange,halfrange+1):
                # modulus arithmetic gives wrap-around of data:
                avg += t[int((y-s*slope) % N)][((x+s) % M)]
            # u array contains stream averages of data in the t array:
            u[y][x] = int(255*avg/(2*halfrange+1))

if  write:
    pickle.dump(u, open(filename, 'w')) # save the texture in a file
else:
    # 'rU' eliminates cross-platform end-of-line problems when reading file:
    u = pickle.load(open(filename, 'rU')) # retrieve the texture from a file
lum = texture(data=u, type="luminance")
# Display 3 by 3 abutted boxes and note smooth connections at edges
#  thanks to the modulus wrap-around algorithm used above:
for x in range(-1,2):
    for y in range(-1,2):
        box(pos=(x,y,0), color=color.orange, texture=lum)
##sphere(pos=(3,0,0), radius=1.5, color=color.cyan, texture=lum)
##sphere(pos=(-3,0,0), radius=1.5, color=color.green, texture=lum)