| """ | |
| ========================================== | |
| 3D voxel / volumetric plot with RGB colors | |
| ========================================== | |
| Demonstrates using `.Axes3D.voxels` to visualize parts of a color space. | |
| """ | |
| import matplotlib.pyplot as plt | |
| import numpy as np | |
| def midpoints(x): | |
| sl = () | |
| for _ in range(x.ndim): | |
| x = (x[sl + np.index_exp[:-1]] + x[sl + np.index_exp[1:]]) / 2.0 | |
| sl += np.index_exp[:] | |
| return x | |
| # prepare some coordinates, and attach rgb values to each | |
| r, g, b = np.indices((17, 17, 17)) / 16.0 | |
| rc = midpoints(r) | |
| gc = midpoints(g) | |
| bc = midpoints(b) | |
| # define a sphere about [0.5, 0.5, 0.5] | |
| sphere = (rc - 0.5)**2 + (gc - 0.5)**2 + (bc - 0.5)**2 < 0.5**2 | |
| # combine the color components | |
| colors = np.zeros(sphere.shape + (3,)) | |
| colors[..., 0] = rc | |
| colors[..., 1] = gc | |
| colors[..., 2] = bc | |
| # and plot everything | |
| ax = plt.figure().add_subplot(projection='3d') | |
| ax.voxels(r, g, b, sphere, | |
| facecolors=colors, | |
| edgecolors=np.clip(2*colors - 0.5, 0, 1), # brighter | |
| linewidth=0.5) | |
| ax.set(xlabel='r', ylabel='g', zlabel='b') | |
| ax.set_aspect('equal') | |
| plt.show() | |