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Prototype of the midpoint displacement algorithm, also known as the diamond square algorithm.heightmap.py creates a triangular mesh represented as a list vertices and indices from a 2d normalized array of values and some parameters. Commonly used as a heightmap.
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import itertools | |
def get_verts_indices_for_heightmap(heightmap, stepx, stepy, minz, maxz): | |
""" heightmap assumed to be normalized (values between 0 and 1) | |
""" | |
height = len(heightmap) | |
width = len(heightmap[0]) | |
spanz = maxz - minz | |
# n_heightmap = width * height | |
# n_tris = n_heightmap * 2 | |
# n_indices = n_tris * 3 | |
indices = [] | |
verts = [] | |
# the indices | |
# embarassingly parallel | |
for i, j in itertools.product(range(width - 1), range(height - 1)) | |
idx = (i * width) + j | |
# 4 points of a grid cell | |
a = idx | |
b = idx + 1 | |
c = idx + width | |
d = idx + width + 1 | |
t1 = (a, c, b) | |
t2 = (b, c, d) | |
indices.extend(t1) | |
indices.extend(t2) | |
# the vertices | |
# embarassingly parallel | |
for i, j in itertools.product(range(width), range(height)) | |
x = j * stepx | |
y = i * stepy | |
z = minz + (normalized_map[i][j] * spanz) | |
vert = (x, y, z)) | |
verts.append(vert) | |
return verts, indices |
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import random | |
def mdp(base, r): | |
# Calculate new dimensions | |
n = len(base) * 2 - 1 | |
assert(n > 2) | |
# Allocate | |
copy = [[0 for _ in range(n)] for _ in range(n)] | |
# Resize | |
# 1 0 1 | |
# 0 0 0 | |
# 1 0 1 | |
for i in range(0, n, 2): | |
for j in range(0, n, 2): | |
copy[i][j] = base[i // 2][j // 2] | |
# Diamond algorithm | |
# 0 0 0 | |
# 0 1 0 | |
# 0 0 0 | |
for i in range(1, n, 2): | |
for j in range(1, n, 2): | |
# get surrounding values | |
a = copy[i - 1][j - 1] | |
b = copy[i - 1][j + 1] | |
c = copy[i + 1][j - 1] | |
d = copy[i + 1][j + 1] | |
# average | |
value = (a + b + c + d) // 4 | |
# random | |
value += random.randint(-r, r) | |
# clamp | |
value = max(value, 0) | |
value = min(value, 255) | |
# store | |
copy[i][j] = value | |
# Square algorithm | |
# 0 1 0 | |
# 1 0 1 | |
# 0 1 0 | |
for i in range(n): | |
for j in range(i % 2 == 0, n, 2): | |
a = 0 | |
b = 0 | |
c = 0 | |
d = 0 | |
# get surrounding values and account for edge cases | |
if (i > 0): a = copy[i - 1][j] | |
if (j > 0): b = copy[i][j - 1] | |
if (i + 1 < n): c = copy[i + 1][j] | |
if (j + 1 < n): d = copy[i][j + 1] | |
# average | |
value = a + b + c + d | |
if (i == 0) or (j == 0) or (i + 1 == n) or (j + 1 == n): | |
value //= 3 | |
else: | |
value //= 4 | |
# random | |
value += random.randint(-r, r) | |
# clamp | |
value = max(value, 0) | |
value = min(value, 255) | |
# store | |
copy[i][j] = value | |
return copy | |
def create_noise(n): | |
return [[random.randint(0, 255) for _ in range(n)] for _ in range(n)] | |
def smoothen(base): | |
n = len(base) | |
for i in range(1, n - 1): | |
for j in range(1, n - 1): | |
base[i][j] = ( | |
base[i - 1][j - 1] + base[i - 1][j] + base[i - 1][j + 1] + | |
base[i + 0][j - 1] + base[i + 0][j] + base[i + 0][j + 1] + | |
base[i + 1][j + 1] + base[i + 1][j] + base[i + 1][j - 1] | |
) // 9 | |
def toPPM(pixels): | |
height = len(pixels) | |
width = len(pixels[0]) | |
buf = [] | |
buf.append("P3") | |
buf.append("%i %i\n%i" % (width, height, 255)) | |
for row in pixels: | |
for pixel in row: | |
r = (pixel >> 16) & 0xFF | |
g = (pixel >> 8) & 0xFF | |
b = pixel & 0xFF | |
buf.append("%i %i %i" % (r, g, b)) | |
return "\n".join(buf) | |
def fromPPM(text): | |
lines = text.splitlines() | |
width, height, _ = (int(x) for x in lines[1].split()) | |
pixels = [[0 for _ in range(width)] for _ in range(height)] | |
lines = reverse(lines) | |
for row in pixels: | |
for i, pixel in enumerate(row) | |
r, g, b = (int(x) for x in lines.pop().split()) | |
row[i] = (r << 16) & (g << 8) & b | |
return pixels | |
import json | |
def save(noise, name): | |
js = json.dumps(noise) | |
with open(name + ".json", "w") as fh: | |
fh.write(js) | |
ppm = toPPM(noise) | |
with open(name + ".ppm", "w") as fh: | |
fh.write(ppm) | |
if (__name__ == "__main__"): | |
noi = create_noise(32) | |
save(noi, "0") | |
for i in range(1, 6): | |
onoi = noi | |
noi = mdp(noi, 64 // i) | |
save(noi, str(i)) |
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import random | |
def createColoredGrid(width, height, padding, nboxes, padding_color, colors): | |
box_len = width // nboxes | |
columns = (width // box_len) + 1 | |
row_colors = [colors[x % len(colors)] for x in range(columns)] | |
pixels = [] | |
for y in range(height): | |
if (y % box_len == 0): | |
random.shuffle(row_colors) | |
row = [padding_color] * width | |
y_offset = y % box_len | |
if (y_offset >= padding and y_offset <= box_len): | |
for x in range(len(row)): | |
x_offset = x % box_len | |
if (x_offset < padding or x_offset > box_len): | |
continue | |
row[x] = row_colors[x // box_len] | |
pixels.append(row) | |
return pixels | |
def toPPM(pixels): | |
height = len(pixels) | |
width = len(pixels[0]) | |
buf = [] | |
buf.append("P3") | |
buf.append("%i %i\n%i" % (width, height, 255)) | |
for row in pixels: | |
for pixel in row: | |
r = (pixel >> 16) & 0xFF | |
g = (pixel >> 8) & 0xFF | |
b = pixel & 0xFF | |
buf.append("%i %i %i" % (r, g, b)) | |
return "\n".join(buf) | |
if (__name__ == "__main__"): | |
colors = [0xffa70f, 0xff4948, 0x700090, 0x878787, 0x8f3900] | |
filler = 0x000000 | |
pixels = createColoredGrid(1600, 1000, 5, 50, filler, colors) | |
ppm = toPPM(pixels) | |
with open("output.ppm", "w") as fh: | |
fh.write(ppm) |
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