Weirdest texture compression bug I've seen. Need help!
I'm working on viking weapon sets. Recently got to making shields. The base idea was to make couple bland wooden shields and then apply paint texture on top of it via masks so I could use material instances later to apply variations of shield patterns. I began to work on the first pattern and used simple black and white mask to just apply paint over the wood to see how it will look and start making more complex texture masking later. A-a-and... Strange thing happened. The colorful pattern texture was... weird.
To fully describe it, let me show you something. So the pattern itself is a wyrm with golden outline on blue background. Here's how it looks in photoshop: Now, I will disable golden outline and import it in ue4:
Looks fine. Smooth lines.
This time, I will enable outlines layer in photoshop, and disable brown coloring: That also looks fine.
And now let's enable both outlines and coloring:
WHAT THE HELL HAPPENED?! (right click the image and open it in new tab to see what I mean)
This is how I first imported the texture in ue4 and saw weird pixels of blue and brown coming from under smooth golden outline. When I begin to try to figure out what causes it, I discovered, that if brown coloring is separated from golden outline, it looks fine. But when they are together - it's all messed up. Which doesn't make any sense! Why is this happening?
I tried different image formats - it doesn't matter. I tried different compression settings in ue4 - on some it fixes the issue, but they increase file size and don't work with applying to mesh as texture.
If anyone has any idea about what is this crap, please share with me! I'm stuck.
ok, set anything thats just grayscale to "alpha" compression setting, its one of the more crisp settings. also for those textures with the "alpha compression" setting, only use the red output, no need for the RGB output. that should help with the crispness without the need to go to 2k.
for additional compression tricks for masks etc look at: https://www.youtube.com/watch?v=mzairog7Elw
In your case you might not want to merge the grayscale channels into an RGB setup but keep em seperate grayscale's set to alpha compression.
If the files are rather small, you can decide to remove mipmaps as well, though shouldn't be needed.
This is expected behavior from DXT1. http://reedbeta.com/blog/understanding-bcn-texture-compression-formats/#bc1
Color channels are not compressed separately and instead each 4x4 block has two endpoints. So blue pixels just bleed over thin outline.
answered Jul 19 '17 at 02:26 PM
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