Hi there,

I want to manually compute mipmaps for an equirectangular texture.

I wrote a compute shader that loads first mip level into LDS using bilinear sampling. Then I'm applying a simple box filtering (using parallel prefix reduction) to output each mip levels.

The above shader was already tested for regular 2d textures.

I noticed however a discontinuity on higher mip levels, exactly where the u axis wraps around, even if I'm loading the LDS using a wrap filtering mode or forcing fract operation for uv coordinates - I can't seem to get rid of the artifact.

I was wondering if anyone else had encountered this artifact when either rendering equirectangular or mipmapping it.

One final note - that artifact can also come from the way that I'm rendering the equirectangular map, but in this shader I'm forcing a specific lod and calculating derivatives manually (to avoid atan discontinuity).

Thanks in advance!

It's obvious that your mapping and/or your filter are wrong, in several ways, but figuring out why is impossible without your rendering and filtering code.