bloom vkCmdBlitImage extents violates valid usage

[AaronHaganAMD]

Q2RTX/src/refresh/vkpt/bloom.c

Line 306 in 0a16c73

extent.width = (extent.width + 3) & ~3;

// Round the extent up to a multiple of 4 to make the downscale blits behave well
extent.width = (extent.width + 3) & ~3;
extent.height = (extent.height + 3) & ~3;

It looks like the blit_mip_0_to_1.srcOffsets[1] is bigger than the size of the src image which is a spec violation.

• VUID-vkCmdBlitImage-pRegions-00215
The source region specified by each element of pRegions must be a region that is
contained within srcImage

What is not behaving well about it ?

[apanteleev]

Thanks for pointing this out!

What is not behaving well about it ?

When the downscale blit input size is not exactly 2x its output size (which happens when the input size is odd), it doesn't do a 2:1 downscale with each output pixel being exactly in the middle of the 4 input pixels. Which breaks the sampling math in the blur pass that follows. To clearly observe this behavior, use these settings:

• drs_enable 1
• drs_target set to something high enough to force lower than 100% render scale
• flt_taa 1 to make post-processing run in render resolution and not output resolution
• bloom_intensity 1.0 and bloom_sigma 0.01 just to make it more obvious

But it's a good point that specifying the extents larger than the texture is a spec violation. I guess that only happens when the output resolution (i.e. window size) is not multiple of 4, which is uncommon. Still, this should be fixed - and I think the right way to fix this would be to do the downscaling in a single compute shader instead of two blits.