When l add windows basic glass shader they turn into black in Cycles. But when I create plane and add same materion onto it it works. I couldn't find the reason.

file link:https://drive.google.com/file/d/1djWPDpvRsxy6ttWzWJLwgqsd33tG3le9/view?usp=sharing

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  • $\begingroup$ could you plase share your file? pasteall.org/blend $\endgroup$
    – moonboots
    Jul 19, 2021 at 11:31
  • $\begingroup$ Hard to say from those screenshots. Are they reflecting something? Are the normals oriented in the right direction? Are those windows floating in the air or do they belong to this pink cube? If so, why is there a windows in a 90° angle between the others? As @moonboots said, please share the file. $\endgroup$ Jul 19, 2021 at 11:33
  • $\begingroup$ drive.google.com/file/d/1djWPDpvRsxy6ttWzWJLwgqsd33tG3le9/… $\endgroup$
    – Olga
    Jul 19, 2021 at 12:00

1 Answer 1


Under Object Data Properties go to Geometry Data and click on the button that says Clear Custom Split Normals Data. I don't know why you have added custom split normals data on your mesh, but this gets rid of the black.

Also disabling Auto Smooth under Normals makes the glass transparent again, but this shouldn't be the problem if there were no custom split normals. Although, since your windows just consist of flat faces in 90° angles, there is no need for Auto Smooth because you could simply shade the windows flat instead of smooth.

custom split normals data


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