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Comment on BC7 Mipmap Problems in Catalina and Mojave
The ticket link is: https://feedbackassistant.apple.com/feedback/9753271 I've verified that our BC7 textures are properly aligned--each mipmap's with and height are proper multiples of blocks (indeed, DirectX and Vulkan also freak out if they aren't). Since each block is 16 bytes this would enforce 16-byte size alignment as well. The pixel data for each level begins on a 16-byte boundary as well. Since our BC7 textures are generated offline I'm not sure what's actually stored in the padded space--the crash is in a swizzle so it's remotely possible there's a stray bit pattern that's causing problems. Most of our textures upload just fine, but I've isolated one that causes the crash and I'm going to try writing a stripped-down application that loads that one texture. The file uses the KTX format so I can also try loading it with MetalKit's texture loader to see if there's a difference there.
Nov ’21