pyqtgraph中的球面坐标图

Question

我刚开始使用pyqtgraph，我想用球坐标制作三维表面图。我已经从文档中看到了示例GLSurfacePlot.py，但是只有笛卡尔坐标中的图。

这是我想制作的情节（它是半波偶极辐射模式）：

如何用pyqtgraph绘制r（theta，phi）？

编辑：我可以用matplotlib mplot3d来做，这是脚本：

import matplotlib.pyplot as plt
import numpy as np
from mpl_toolkits.mplot3d import Axes3D

k = 2*np.pi
long = 0.5
theta = np.linspace(0, np.pi, 361)
phi = np.linspace(0, 2*np.pi, 361)
PHI, THETA = np.meshgrid(phi, theta)
R = np.absolute((np.cos(k*long/2*np.cos(THETA))-np.cos(k*long/2))/np.sin(THETA))
R = np.nan_to_num(R)
X = R * np.sin(THETA) * np.cos(PHI)
Y = R * np.sin(THETA) * np.sin(PHI)
Z = R * np.cos(THETA)

fig = plt.figure()
ax = fig.add_subplot(111, projection = '3d')
cmap = plt.get_cmap('jet')
plot = ax.plot_surface(X, Y, Z, rstride=10, cstride=10, facecolors=cmap(R),linewidth=0, antialiased=False, alpha=1)

plt.show()

问题是它在旋转和缩放时太慢了，我的应用程序肯定需要这个功能，这就是为什么我要用pyqtgraph来做这个。

Answer 1

通过GLSurfacePlotItem无法绘制此类公式，在这种情况下，您必须使用GLMeshItem，但为此您必须创建一个合适的MeshData，因此需要作为参考sphere获得以下功能：

def DipoleData(rows, cols, func, args=None):
    verts = np.empty((rows+1, cols, 3), dtype=float)
    phi = (np.arange(rows+1) * 2*np.pi *(1+2/rows)/ rows).reshape(rows+1, 1)
    th = ((np.arange(cols) * np.pi / cols).reshape(1, cols)) 

    if args is not None:
        r = func(th, phi, *args)
    else:
        r = func(th, phi)
    s =  r* np.sin(th)
    verts[...,2] = r * np.cos(th)
    verts[...,0] = s * np.cos(phi)
    verts[...,1] = s * np.sin(phi)

    verts = verts.reshape((rows+1)*cols, 3)[cols-1:-(cols-1)]  ## remove redundant vertexes from top and bottom
    faces = np.empty((rows*cols*2, 3), dtype=np.uint)
    rowtemplate1 = ((np.arange(cols).reshape(cols, 1) + np.array([[0, 1, 0]])) % cols) + np.array([[0, 0, cols]])
    rowtemplate2 = ((np.arange(cols).reshape(cols, 1) + np.array([[0, 1, 1]])) % cols) + np.array([[cols, 0, cols]])
    for row in range(rows):
        start = row * cols * 2 
        faces[start:start+cols] = rowtemplate1 + row * cols
        faces[start+cols:start+(cols*2)] = rowtemplate2 + row * cols
    faces = faces[cols:-cols]  ## cut off zero-area triangles at top and bottom

    ## adjust for redundant vertexes that were removed from top and bottom
    vmin = cols-1
    faces[faces<vmin] = vmin
    faces -= vmin  
    vmax = verts.shape[0]-1
    faces[faces>vmax] = vmax

    return gl.MeshData(vertexes=verts, faces=faces)

然后在以下示例中使用它：

app = QtGui.QApplication([])
w = gl.GLViewWidget()
w.opts['distance'] = 3
w.show()
w.setWindowTitle('Half Wave Dipole Radiation Pattern')

def r_theta_phi(theta, phi, k, l):
    return np.absolute((np.cos((k*l/2)*np.cos(theta)) -np.cos(k*l/2))/np.sin(theta))

p = 2*np.pi
q = 0.5

md = DipoleData(100, 100, r_theta_phi, args=(p, q))
colors = np.ones((md.faceCount(), 4), dtype=float)
colors[:,0] = np.linspace(0.1, 0.2, colors.shape[0])
colors[:,1] = np.linspace(0.2, 0.9, colors.shape[0])
colors[:,2] = np.linspace(0.0, 0.1, colors.shape[0])
md.setFaceColors(colors)
m = gl.GLMeshItem(meshdata=md, smooth=False)
w.addItem(m)

ax = gl.GLAxisItem()
ax.setSize(100,100,100)
w.addItem(ax)

g = gl.GLGridItem()
g.scale(0.2, 0.2, 0.2)
w.addItem(g)

## Start Qt event loop unless running in interactive mode.
if __name__ == '__main__':
    import sys
    if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
        QtGui.QApplication.instance().exec_()

获取下图中显示的内容：