I am currently grappling with the computation of mipmaps for block compressed formats (BC7) in Vulkan. The limitation with these formats is that the size of the block compressed texture needs to be a multiple of 4. While I can comfortably make this adjustment for the level 0 of the mipmap chain, subsequent levels, which are half the size of the preceding level, present a challenge. For instance, if the size of level i is a multiple of 4, level i + 1 doesn't necessarily have to be. Could it be feasible to sidestep the traditional rules of image mip level sizing and establish custom sizes for each level?

Here's an illustrative example:

Level 0: 1080x1080 (remains 1080x1080)

Level 1: 540x540 (remains 540x540)

Level 2: 270x270 (becomes 272x272)

Level 3: 135x135 (becomes 136x136)


Level n: 4x4

I've also explored the possibility of converting Non-Power-Of-Two (NPOT) images to Power-Of-Two images. This adjustment could resolve the problem as the entire mipmap chain would then possess sizes that are multiples of 4 (with the exception of 2x2, 1x1, etc.). However, this approach seems suboptimal, particularly when a 1027x1027 texture would have to be adjusted to 2048x2048.

Given these considerations, what possible solutions could be implemented to tackle this problem?



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