Hoping to get some help understanding the behaviour I have noticed here. Let me know if there’s anything else I can provide to help explain the situation.
Recreating the problem:
Take a 2d background image (mine is of a room interior)
Use GIMP to carefully select an object from the image, and cut the image into a new image.
Clean up the new image to have transparency around the edges.
Export new image as a .PNG (I’ve tried with all options on and off related to transparency)
Load PNG as an asset (sprite 2d or UI) in the project
Place sprite into the scene.
–NOTE-- at this point, everything looks fine. The transparent “edges” are indeed transparent.
Switch Scene/Editor view to “Render Paths”
–PROBLEM-- somehow the old background image from whence the new image came from can be seen in the transparent “edges” around the image.
Attempts to fix:
Used alternative programs for each step, including re-filling the transparent sections with a colour, saving the file, flattening the image again to be safe, and then adding the transparency back in. No change.
Googled and forum searched with no results from anyone experiencing the same issue, possibly due to being challenging to explain in a short sentence.
New scene, several new images etc etc.
Why are you trying to fix this? Render Paths is a debug view for showing what objects on screen are being rendered using deferred or forward rendering paths … and sprites will generally always be forward.
As for what you’re seeing, that’s the color data that’s in the PNG file where it’s fully transparent. It’s not necessarily what was in the image prior to you cutting it out, but more likely artifacts from how the PNG compression decided to handle the “blank” areas. Since there is still color data in those areas of fully transparency, PNG still has to compress it, and oddly those stripes end up being more efficient than a solid color. It could also be an artifact of Unity’s dilation if you have Alpha is Transparency checked on the import settings. This too will create weird stripes in the color data, but they’re there to try to keep the transparent edges from showing fringing due to bilinear sampling and mip mapping.
Ok, thank you for the response. I have noticed some issues with certain shaders being applied which ends up showing the polygons around the image as well. This can be reduced by using TexturePacker which is far more efficient than GIMP, so I was thinking that it was something I needed to fix. Perhaps I’m just overthinking it and also using the wrong shaders.
Sprites should generally only use sprite shaders, otherwise you want to stick to shaders that support transparency or alpha test. If you’re using a shader that doesn’t support alpha of some kind you’ll see that color data that you don’t want in the transparent areas.