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85 lines
2.5 KiB
Markdown
85 lines
2.5 KiB
Markdown
# 多三角三维曲面
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使用三角形网格绘制曲面的另外两个示例。
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第一个演示使用plot_trisurf的三角形参数，第二个设置Triangulation对象的蒙版并将对象直接传递给plot_trisurf。
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```python
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import numpy as np
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import matplotlib.pyplot as plt
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import matplotlib.tri as mtri
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# This import registers the 3D projection, but is otherwise unused.
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from mpl_toolkits.mplot3d import Axes3D # noqa: F401 unused import
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fig = plt.figure(figsize=plt.figaspect(0.5))
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#============
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# First plot
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#============
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# Make a mesh in the space of parameterisation variables u and v
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u = np.linspace(0, 2.0 * np.pi, endpoint=True, num=50)
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v = np.linspace(-0.5, 0.5, endpoint=True, num=10)
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u, v = np.meshgrid(u, v)
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u, v = u.flatten(), v.flatten()
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# This is the Mobius mapping, taking a u, v pair and returning an x, y, z
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# triple
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x = (1 + 0.5 * v * np.cos(u / 2.0)) * np.cos(u)
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y = (1 + 0.5 * v * np.cos(u / 2.0)) * np.sin(u)
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z = 0.5 * v * np.sin(u / 2.0)
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# Triangulate parameter space to determine the triangles
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tri = mtri.Triangulation(u, v)
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# Plot the surface. The triangles in parameter space determine which x, y, z
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# points are connected by an edge.
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ax = fig.add_subplot(1, 2, 1, projection='3d')
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ax.plot_trisurf(x, y, z, triangles=tri.triangles, cmap=plt.cm.Spectral)
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ax.set_zlim(-1, 1)
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#============
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# Second plot
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#============
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# Make parameter spaces radii and angles.
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n_angles = 36
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n_radii = 8
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min_radius = 0.25
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radii = np.linspace(min_radius, 0.95, n_radii)
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angles = np.linspace(0, 2*np.pi, n_angles, endpoint=False)
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angles = np.repeat(angles[..., np.newaxis], n_radii, axis=1)
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angles[:, 1::2] += np.pi/n_angles
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# Map radius, angle pairs to x, y, z points.
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x = (radii*np.cos(angles)).flatten()
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y = (radii*np.sin(angles)).flatten()
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z = (np.cos(radii)*np.cos(3*angles)).flatten()
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# Create the Triangulation; no triangles so Delaunay triangulation created.
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triang = mtri.Triangulation(x, y)
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# Mask off unwanted triangles.
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xmid = x[triang.triangles].mean(axis=1)
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ymid = y[triang.triangles].mean(axis=1)
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mask = np.where(xmid**2 + ymid**2 < min_radius**2, 1, 0)
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triang.set_mask(mask)
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# Plot the surface.
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ax = fig.add_subplot(1, 2, 2, projection='3d')
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ax.plot_trisurf(triang, z, cmap=plt.cm.CMRmap)
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plt.show()
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```
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## 下载这个示例
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- [下载python源码: trisurf3d_2.py](https://matplotlib.org/_downloads/trisurf3d_2.py)
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- [下载Jupyter notebook: trisurf3d_2.ipynb](https://matplotlib.org/_downloads/trisurf3d_2.ipynb) |