Lightmaps as KTX2 UASTC encoding

Yo @Evgeni_Popov … I got a question about lightmaps…

Right now, i currently PACK my lightmaps into a RGBD/PNG image.

Is there ANY advantage to further encoding those lightmaps as KTX2.

Without using lossy compression that ktx2 image file can be quite large… i am assuming because of the full mipmap chain.

Should i keep lightmaps as RGBD packed PNG files or should i go ahead and convert those lightmaps to KTX2 with toktx.exe ???

I don’t really know…

I think the best way is to test. You should try to use etc1s which compresses better than uastc. I think it should work ok for a lightmap.

Or maybe the easiest: just give the choice to the user to use rgbd/png or ktx2 for lightmaps, that way it’s up to the user to decide what they want to use.


If i just use –uastc 2 as the args… the light maps look crappy, not anywhere as clean as RGBD packed png.

What would be the toktx to create a mipmap ktx2 with LOSSLESS compression so that lightmaps dont look like crap… Or i guess i could always keep lightmaps as PNG.

There’s no lossless compression with uastc/etc1s I think, that’s the point of the format, to have lower texture sizes. You can try to use other levels for uastc and see if that helps (the 2 in --uastc 2).

It seems ktx2 lightmaps are working ok for him: GitHub - 0beqz/lightmap_interior_test: three.js lightmap interior test

I will try without RGBD packing the png before converting to ktx2

Also , I thought the point of ktx was preparing the texture for GPU… like pre mipmapoing… and the compression was another feature

But I understand if everything has some compression on

Maybe this doc will help shed some light: