python - 为什么使用 ax.pltsurface 创建的球体无法在曲面的各个面上保持所需的 alpha=1 ？

Question

I am showing a color map as the facecolors of a sphere using ax.plt_surface. Basically is the example that is available at the pyplot webpages, with some extra code to add the color map. The application generates a complex function f(z)=z^3+1 for z=a+bi where a=[-4,4] and b=[-3,3]. Then the domain color map of the function is done, it is a [200]x[200]x3 numpy array (the typical one). Finally the sphere is created and I want to use the color map as the filling color of the faces of the surface of the sphere, so basically I want to map the color map as the "texture" of the sphere.

def sphere_mapping():
    import numpy as np
    import matplotlib.pyplot as plt
    import skimage, skimage.io
    from mpl_toolkits.mplot3d import Axes3D
    from math import sqrt, atan2, pi

    def hslToRgb(h, s, l):
        # Source: https://stackoverflow.com/questions/2353211/hsl-to-rgb-color-conversion
        # Converts an HSL color value to RGB. Conversion formula
        # adapted from http://en.wikipedia.org/wiki/HSL_color_space.
        # Assumes h, s, and l are contained in the set [0, 1] and
        # returns r, g, and b in the set [0, 1].
        def hue2rgb(p, q, t):
            if t < 0:
                t += 1
            if t > 1:
                t -= 1
            if t < 1/6:
                return p + (q - p) * 6 * t
            if t < 1/2:
                return q
            if t < 2/3:
                return p + (q - p) * (2/3 - t) * 6
            return p

        r,g,b = 0,0,0

        if s == 0:
            r,g,b = l,l,l
        else:
            q=0
            if l < 0.5:
                q=l * (1 + s)
            else:
                q=l + s - l * s

            p = 2 * l - q;
            r = hue2rgb(p, q, h + 1/3)
            g = hue2rgb(p, q, h)
            b = hue2rgb(p, q, h - 1/3)

        return r,g,b

    # Displays an image
    def display(img, colorbar=False, filename=""):
        plt.figure(figsize=(10, 10))
        if len(img.shape) == 2:
            i = skimage.io.imshow(img, cmap='gray')
        else:
            i = skimage.io.imshow(img)
        if colorbar:
            plt.colorbar(i, shrink=0.5, label='depth')
        plt.tight_layout()
        if filename=="":
            plt.show()
        else:
            plt.savefig(filename)

    plt.rcParams['figure.dpi'] = 150    

    # complex function f(z) calculations start here
    testlimitx = 100
    testlimity = 100
    testbase = 100

    anim=0
    lx=[]
    ly=[]
    lc=[]

    lh=[]
    ll=[]
    lr=[]
    ls=[]

    print("Calculating...")
    maxx=0
    maxy=0

    for posx in range(-testlimitx,testlimitx):
        for posy in range(-testlimity,testlimity):

            x=(posx/testbase)*1
            y=(posy/testbase)*1

            # function complex example
            myc=x+(y*(1j))
            myc=(myc**3)+1

            resx=myc.real
            resy=myc.imag

            if abs(resx)>maxx:
                maxx=abs(resx)
            if abs(resy)>maxy:
                maxy=abs(resy)

            current_angle = 0
            current_r = sqrt((resx**2)+(resy**2))
            if resx!=0:
                current_angle = atan2(resy,resx)
            else:
                if y>0:
                    current_angle = pi/2
                else:
                    current_angle = (pi/2)*3

            if current_angle < 0:
                current_angle = current_angle + (2*pi)

            current_angle = (1/(2*pi))*current_angle

            h = current_angle
            l = 0.5
            s = 0.7

            lx.append(x)
            ly.append(y)

            lh.append(h)    
            ll.append(l)    
            ls.append(s)
            lr.append(current_r)    

    for i in range(0,len(lx)):
        r,g,b = hslToRgb(lh[i], ls[i], ll[i])

        # lc contains 200x200x3 R,G,B color values
        lc.append(r)
        lc.append(g)
        lc.append(b)

    print("Creating colormap ...")
    colormap = np.zeros((200, 200, 3), dtype=np.float)
    pos=0
    for i in range (0,200):
        for j in range (1,201):
            colormap[200-j][i][0]=lc[pos]
            pos=pos+1
            colormap[200-j][i][1]=lc[pos]
            pos=pos+1
            colormap[200-j][i][2]=lc[pos]
            pos=pos+1
            print("Current index="+str(i)+","+str(j)+"\r", end='')

    # finally this is the colormap that has been generated
    display(colormap)

    # sphere test: will map the colormap into the surface of the sphere
    n=200
    m=200
    u = np.linspace(0,2*pi,n)
    v = np.linspace(0,pi,m)

    x = np.outer(np.cos(u),np.sin(v))
    y = np.outer(np.sin(u),np.sin(v))
    z = np.outer(np.ones(n),np.cos(v))

    fig = plt.figure()
    fig.patch.set_alpha(1)
    ax = fig.gca(projection='3d')
    ax.view_init(elev=0., azim=-180)    

    col1 = np.empty([n,m,3], dtype=float)
    for i in range(0,len(col1)):
        for j in range(0,len(col1[i])):
            col1[i][j][1]=colormap[j][i][0]
            col1[i][j][1]=colormap[j][i][1]
            col1[i][j][2]=colormap[j][i][2]

    ax.plot_surface(x,y,z,color='b',rstride=1, cstride=1, alpha=1.0, linewidth=0, facecolors=col1)
    plt.show()
    plt.savefig("sphere_test.png", dpi=600)

sphere_mapping()

上述示例的颜色图图像如下:

但是当我将图像映射到 numpy 数组“col1”后将其视为球体的表面时(映射只是因为点的颜色信息位于数组的不同位置，但维度两个数组的颜色是相同的)，颜色不匹配，我猜这是由于一些不需要的透明度，所以我无法完全看到我所面对的当前面的颜色(由于透明度，我可以看到隐藏的一面也是如此，并且颜色正在混合)。我添加了 alpha=1.0 但似乎没有达到预期的效果。我期待完全相同的颜色，没有透明度，因此不会出现混合颜色。

我不确定这是否与 topic in this previous question 有关.

目前我正在使用以下参数进行 ax.plotsurface 调用:

ax.plot_surface(x,y,z,color='b',rstride=1, cstride=1, alpha=1.0, linewidth=0, facecolors=col1)

Is it possible to fix this problem? Thank you!

Answer 1

是否唯一的问题是颜色到 col1 的映射。而不是

col1[i][j][1]=colormap[j][i][0]col1[i][j][1]=colormap[j][i][1]col1[i][j][2]=colormap[j][i][2]

你可能想要

col1[i][j][0]=colormap[j][i][0]col1[i][j][1]=colormap[j][i][1]col1[i][j][2]=colormap[j][i][2]