How to use Vispy to draw different types of line by different times?

Question

I want to draw different types of lines, such as, white lane, yellow lane, white long lane and so on, but when I call visual.Line() eachtime, it can only keep the last draw-event , just only one type of lane in the Canvas. Does Vispy has the same or likely operation like plot, we can plot different lines by calling plot times? Can anybody help me, I will be appreciated it a lot!

Here is code:

    for i in range(len(white_lane_nodes)-1): 
        white_lane = visuals.Line(pos=white_lane_nodes[i], 
                           connect=lane_pair, 
                           color=white, 
                           parent=view.scene)
    
    for i in range(len(yellow_lane_nodes)-1):
        yellow_lane = visuals.Line(pos=yellow_lane_nodes[i],
                           connect=lane_pair,
                           color=orange,
                           parent=view.scene)

I tried the example code to update line, but it didn't works the way that I want, I dont need the Timer.

    def update(event):
        for line in lines:
             cale = [np.sin(np.pi * event.elapsed)+2,
             np.cos(np.pi * event.elapsed)+2]
             line.transform.scale = scale

    timer = app.Timer('auto', connect=update, start=True)

Answer 1

You mean this example, right?

https://vispy.org/gallery/scene/line.html

In that original example code, this is how the lines are created:

lines = []

print('Generating points...')
for i in range(20):
    pos = pos.copy()
    pos[:, 1] = np.random.normal(scale=5, loc=(i+1)*30, size=N)
    line = scene.visuals.Line(pos=pos, color=color, parent=canvas.scene)
    lines.append(line)
    line.transform = scene.transforms.STTransform()

Note how the line objects are created (line = scene.visuals.Line) and then stored in a lines list (lines.append(line)). Your code doesn't seem to have this list of lines. Try adding that back in and it should work.

If that doesn't work, check the output of your script for errors. If there are any you can update your question above with the new information and comment on this answer to let me know that you've made an update.