Transparent cube surface, it is a bug?

[Nanguage]

Hi,
I'm a newbie of OpenGL and glumpy. When I try to run the code in chapter5, such as outlined-cube.py and textured-cube.py, I found that my cube looks like different to the images in the tutorial. It looks like has transparent surface. I do n’t know what went wrong

Here is my screenshot gif:

My environment:

Windows10 WSL Ubuntu 16.04
Display with Xming X11

Python: 3.7.6
glumpy: 1.0.6
pyopengl: 3.1.5
triangle: 20200404

[rougier]

Nice animation :) Your probably did not activate the depth test that is necessary in this case.

[Nanguage]

Thnaks for your response. I noticed that there is gl.glEnable(gl.GL_DEPTH_TEST) in the module textured-cube.py. I mean I have never changed its code. Is there something else I can do to activate it or debug it?

[rougier]

Hum, weird. Can you try to run some of the glumpy examples to check if they're working?