René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[Bug]: Surface draws incorrectly after set_verts on Poly3DCollection ","articleBody":"### Bug summary\n\nSurface is not rendered properly after changing the data using `set_verts`: the simple MWE below shows the effect.\n\n### Code for reproduction\n\n```python\nimport numpy as np\r\nimport matplotlib.pyplot as plt\r\nimport matplotlib.animation as animation\r\n\r\nx = np.array([10, -10])\r\ny = np.array([25, -25])\r\nz = 5\r\n\r\nX, Y = np.meshgrid(x, y)\r\nZ = z * np.ones_like(X)\r\n\r\nfig = plt.figure(figsize=(8, 4.5))\r\nax = fig.add_subplot(projection=\"3d\")\r\n\r\nax.axes.set_xlim3d(left=-15, right=15)\r\nax.axes.set_ylim3d(bottom=-30, top=30)\r\nax.axes.set_zlim3d(bottom=0, top=10)\r\n\r\nsurf = ax.plot_surface(X, Y, Z, color=\"r\", alpha=0.3)\r\nplt.pause(1.0)\r\n\r\ntime = np.linspace(0, 5, 101)\r\nfor t in time:\r\n    zt = z + 2 * np.sin(2 * np.pi * t)\r\n    Z = zt * np.ones_like(X)\r\n    verts = np.array([X, Y, Z]).T.reshape(4, 3)\r\n    surf.set_verts(verts)\r\n    plt.pause(0.1)\n```\n\n\n### Actual outcome\n\n![image](https://user-images.githubusercontent.com/31228546/134621319-44d6f5c3-b30b-462a-adf5-bd1b3da185e4.png)\r\n\n\n### Expected outcome\n\nThe full surface, as is shown prior to updating using `set_verts` should be shown:\r\n\r\n![image](https://user-images.githubusercontent.com/31228546/134621409-f08ddb48-aebf-496f-b919-116c394f0d3d.png)\r\n\n\n### Operating system\n\nUbuntu 21.04\n\n### Matplotlib Version\n\n3.4.2\n\n### Matplotlib Backend\n\nQt5Agg\n\n### Python version\n\n3.8.11\n\n### Jupyter version\n\n_No response_\n\n### Other libraries\n\n_No response_\n\n### Installation\n\nconda\n\n### Conda channel\n\n_No response_","author":{"url":"https://github.com/ccaprani","@type":"Person","name":"ccaprani"},"datePublished":"2021-09-24T05:10:16.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":11},"url":"https://github.com/21163/matplotlib/issues/21163"}