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When I draw an image with transparent edges, the renderer (I am using P3D) is drawing a thin grey line around the border of the image, which is visible despite the fact that the edges of the image are transparent. There are also some other wierd grey lines around various images. Does anyone know how to fix this?
I have found other posts about this issue on the processing forum: https://forum.processing.org/one/topic/transparent-png-issue.html And of this and similar issues on openGl forums: https://opengl.org/discussion_boards/showthread.php/167808-2D-texture-problem-lines-between-textures https://opengl.org/discussion_boards/showthread.php/178038-Black-lines-at-edges-of-textures
The post on the processing forum does not have a solution (and isn't really the same problem). It seems there might be a way to fix this by adjusting OpenGL settings, but I don't know how to do that with processing. I am using OpenGL because I have to render a very large number of pixels in 3D space every frame, and I doubt other renderers will work as well. Here are some images (I scaled some of these up to show the problem, the lines are all exactly 1 pixel in the original (they seem to actual be one pixel on my retina display, not one processing pixel):
The lines in the middle of these images are added by the renderer, they are at the edge of a partially transparent image.
This is the border between two images (each drawn on a textured polygon, with uv mapping). The black line in the middle is not part of either image. That line is not on the edge of where the image is being drawn, but on the edge of the opaque part of an image. This image also has a line on the very edge.
The borders between some textures without any transparency still get weird lines.