How to draw points of a sphere in a cubic environment?

Given a center point (x0, y0, z0) and a radius (g_radius) I want to use Python to generate points in a sphere in a cubic world (= Minecraft).

I’m trying to use this algorithm (I found it here on so) but it’s not precise and I have to increase the number of samples to a ridiculous huge number to get almost all the points, but it’s still not 100% accurate:

num_pts = 10000000
indices = arange(0, num_pts, dtype=float) + 0.5
phi = arccos(1 - 2 * indices / num_pts)
theta = pi * (1 + 5 ** 0.5) * indices
t_x, t_y, t_z = cos(theta) * sin(phi), sin(theta) * sin(phi), cos(phi)
tmp = [(g_x0 + int(x * g_radius),
        g_y0 + int(y * g_radius) + g_radius,
        g_z0 + int(z * g_radius))
       for (x, y, z) in zip(t_x, t_y, t_z)]
final_coord_result = list(set(tmp))

Here’s what you get with a small radius (5):

How would you do this?

Answer

This sounds like a job for raster_geometry:

import raster_geometry
from matplotlib import pyplot as plt

# define degree of rasterization
radius = 7.5

# create full sphere
sphere_coords = raster_geometry.sphere(int(2*radius), radius)
# make it hollow
sphere_coords = raster_geometry.unfill(sphere_coords)

# plot it
ax = plt.figure().add_subplot(111, projection='3d')
ax.scatter(*sphere_coords.nonzero())
plt.show()