KTX2 UASTC alpha not working on Safari 15.*

Hi there! I’ve been getting some feedback that the alpha channel isn’t working on our KTX2 UASTC textures but only on Safari. I’ve tested this and seen this happen on Safari versions 15.0, 15.2 and 15.3 so far. ETC1S seems to be ok.

I’ve made a small scene to help test the issue:

Please let me know if you need any other information to help resolve the issue.

I think @bghgary worked on this recently and it was fixed by Safari on 15.4 ?

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Thank you for the reply Sebavan. 15.4 and 15.5 are working for me. Do you know if Safari is also looking to impliment the fix for the older versions?

I do not think Safari will ever retrofit any fixes :frowning: Maybe @bghgary has a trick for those.

I haven’t looked at this yet, but we should be able to fallback to a different format if iOS has issues for older versions, assuming we can tell the difference.

I don’t see an easy way to downgrade my iPhone to an older version and this will make it very difficult to determine how to fix it. Is fixing this for older versions a big issue? Apple tends to want everyone to upgrade to the latest.

Thank you again for the replies. We have added a version check to use a different format for the old Safari versions. As mentioned this problem should resolve itself as everyone upgrades.