在Vispy中的特定位置绘制球体

如何解决在Vispy中的特定位置绘制球体

我在Vispy中有一个3D散点图，其中每个点代表一个数据样本。为了这个问题，我使用了一些虚假数据。当我单击某个点时，它会更改为白色，以显示当前选中的点。

我停留的部分：我想在所选点的顶部绘制一个透明的球体。但是以某种方式，我无法正确地将球体放置在所需位置。

我的例子：

import numpy as np
from vispy import app,visuals,scene,color
from sklearn.manifold import TSNE
import matplotlib.cm as cm
from vispy.visuals.transforms import STTransform

class Visualizer():
    def __init__(self):
        # fake data
        self.data = np.random.normal(0,1,(100,3))
        print(self.data.shape)

        self.colors = cm.rainbow(np.linspace(0,self.data.shape[0]))
        self.init_colors = cm.rainbow(np.linspace(0,self.data.shape[0]))

        self.canvas = np.zeros((480,640))

    def distance_traveled(self,positions):
        """
        Return the total amount of pixels traveled in a sequence of pixel
        `positions`,using Manhattan distances for simplicity.
        """
        return np.sum(np.abs(np.diff(positions,axis=0)))

    def scatter3d(self,positions,colors,symbol='o',size=12,click_radius=2,on_click=None):

        """
        Create a 3D scatter plot window that is zoomable and rotateable,with
        markers of a given `symbol` and `size` at the given 3D `positions` and in
        the given RGBA `colors`,formatted as numpy arrays of size Nx3 and Nx4,respectively. Takes an optional callback function that will be called with
        the index of a clicked marker and a reference to the Markers visual
        whenever the user clicks a marker (or at most `click_radius` pixels next to
        a marker).
        """
        # based on https://github.com/vispy/vispy/issues/1189#issuecomment-198597473
        # create canvas
        canvas = scene.SceneCanvas(keys='interactive',show=True,bgcolor='gray')
        # create viewbox for user interaction
        view = canvas.central_widget.add_view()
        view.camera = 'turntable'
        view.camera.fov = 45
        view.camera.distance = abs(positions).max() * 2.5
        # create visuals
        p1 = scene.visuals.Markers(parent=view.scene)
        p1.set_gl_state('translucent',blend=True,depth_test=True)
        # axis = scene.visuals.XYZAxis(parent=view.scene)
        # set positions and colors
        kwargs = dict(symbol=symbol,size=size,edge_color=None)
        p1.set_data(positions,face_color=self.colors,**kwargs)
        print(p1._data)

        print(positions)
        # prepare list of unique colors needed for picking
        ids = np.arange(1,len(positions) + 1,dtype=np.uint32).view(np.uint8)
        ids = ids.reshape(-1,4)
        ids = np.divide(ids,255,dtype=np.float32)
        # connect events
        if on_click is not None:
            def on_mouse_release(event):
                if event.button == 1 and self.distance_traveled(event.trail()) <= 2:
                    # vispy has some picking functionality that would tell us
                    # whether any of the scatter points was clicked,but we want
                    # to know which point was clicked. We do an extra render pass
                    # of the region around the mouseclick,with each point
                    # rendered in a unique color and without blending and
                    # antialiasing.
                    pos = canvas.transforms.canvas_transform.map(event.pos)
                    try:
                        p1.update_gl_state(blend=False)
                        p1.antialias = 0
                        p1.set_data(positions,face_color=ids,**kwargs)
                        img = canvas.render((pos[0] - click_radius,pos[1] - click_radius,click_radius * 2 + 1,click_radius * 2 + 1),bgcolor=(0,0))
                    finally:
                        p1.update_gl_state(blend=True)
                        p1.antialias = 1
                        p1.set_data(positions,**kwargs)
                    # We pick the pixel directly under the click,unless it is
                    # zero,in which case we look for the most common nonzero
                    # pixel value in a square region centered on the click.
                    idxs = img.ravel().view(np.uint32)
                    idx = idxs[len(idxs) // 2]
                    if idx == 0:
                        idxs,counts = np.unique(idxs,return_counts=True)
                        idxs = idxs[np.argsort(counts)]
                        idx = idxs[-1] or (len(idxs) > 1 and idxs[-2])
                    # call the callback function
                    if idx > 0:
                        # subtract one; color 0 was reserved for the background
                        on_click(idx - 1,p1)

                    sphere = scene.visuals.Sphere(radius=0.2,rows=10,cols=10,depth=10,method='cube',parent=view.scene,edge_color='black')

                    # The problematic line
                    sphere.transform = STTransform(translate=self.data[idx])

            canvas.events.mouse_release.connect(on_mouse_release)

        # run application
        app.run()

    def run(self):
        def on_click(idx,markers):
            self.colors = self.init_colors.copy()
            self.colors[idx] = (1,1)

            markers.set_data(self.data,edge_color=None)

        self.scatter3d(self.data,self.colors,on_click=on_click)

visualizer = Visualizer()
visualizer.run()

在此示例中，我使用numpy创建了一堆随机数据并将其绘制。但是我不知道如何正确地变换所选点的坐标以在其上方绘制球体。 Vispy的set_data()在这些点上执行哪些转换？

我试图用canvas.transforms.canvas_transform.map()变换点，但这是不正确的。