nightscrawl Posted February 17, 2019 Share Posted February 17, 2019 I don't understand why I'm getting these artifacts when saving normals with BC7. The normal itself looks fine; the alpha layer looks like crap. https://i.imgur.com/EjfS68P.jpg Link to comment Share on other sites More sharing options...
FrankFamily Posted February 18, 2019 Share Posted February 18, 2019 The alpha channel of a bc7 will sometimes have much more artifacts than dxt5, rgb wil be preserved better though. So, dont use bc7 blindly, compare and decide what looks better ingame. Link to comment Share on other sites More sharing options...
nightscrawl Posted February 19, 2019 Author Share Posted February 19, 2019 Damn I was hoping there was something I could do to "fix" it. That idea seems to go against the current popular wisdom of saving all (new) normals as BC7. When does a normal need an alpha? I tend to go by whatever the default image has, but I don't know if that's an accurate guide. I know your work though, and that you have far more experience than I, so thanks for the response! Link to comment Share on other sites More sharing options...
FrankFamily Posted February 21, 2019 Share Posted February 21, 2019 (edited) A bit late. Well, popular wisdom isn't always 100% correct, it isn't really incorrect either. For most normal maps there will be a significant improvement in saving new normals in bc7 since artifacts in the normal are generally very noticiable. But if the normal map has a lot of information, for example, if you have some sort of very small cloth pattern where practically every pixel is significantly different from its neighbors. I imagine this is your case, lots of variation in the leaves. BC7 preserves that detail in the normal map way better than dxt5 but the alpha channel is worse. I guess in attempting to keep that information in RGB channels better than DXT5 the alpha channel suffers. Both formats end up weighting the same so I suppose there has to be some sort of tradeoff, makes sense. In most cases I'd still use BC7 because DXT5 will destroy the detail in the normal map. If both formats are not good for a particular texture then uncompressed is always an option, albeit a costly one. Normal map's alpha is the specular channel in all assets I have experience with, and they will all have it. In enviromental textures or creatures it might be different. Following vanilla is a good method I'd say. Edited February 21, 2019 by FrankFamily Link to comment Share on other sites More sharing options...
FrankFamily Posted February 21, 2019 Share Posted February 21, 2019 (edited) So, to not spread misinformation I figured I could actually test this in the most objective manner I could think of. Here, pretty self explanatory: Note this behaviour may only apply to the particulary noisy areas of a texture. Edited February 22, 2019 by FrankFamily Link to comment Share on other sites More sharing options...
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