import numpy as np
from matplotlib import pyplot as plt
for _i in range(4):
for _j in range(4):
a = 100
mid = a//2
img_w = a
img_h = a
r = a * 0.4
img = [[0 for j in range(img_w)] for i in range(img_h)]
l = np.array([-1., 1., 1.])
l /= np.linalg.norm(l, ord=2)
e = np.array([0, 0, 1])
diff = 0.3
spec = _i * 0.2
spow = _j * _j + 1
ambi = 0.1
for i in range(img_h):
for j in range(img_w):
x = (j-mid) / r
y = -(i-mid) / r
if x*x+y*y < 1:
z = (1-x**2-y**2)**0.5
n = np.array([x, y, z])
h = l+e
h /= np.linalg.norm(h, ord=2)
c = ambi + diff * max(0, np.dot(n, l)) + \
spec * (max(0, np.dot(n, h)) ** spow)
img[i][j] = c
plt.subplot(4,4,_i*4+_j+1)
plt.imshow(img, cmap='gray', vmin = 0, vmax = 1)
plt.show()