'Tis the season for emulator enhancement projects. First, we've seen
bsnes adding a high-definition Mode 7 upscaling feature, then
a widescreen Game Boy emulator got released, and now it looks like mGBA will be receiving something fancy too!
One of the planned features for its next release is a high-res OpenGL renderer, which will allow for a variety of graphical improvements. Like the previously mentioned bsnes-hd, you can expect games using a Mode 7-like perspective effect (for example, F-ZERO ones and Mario Kart: Super Circuit) to look less pixelated when scaled. However, this time it doesn't just end there: sprite rotations and transformations have also been enhanced, as well as other display modes and miscellaneous graphical features! This means a good number of games will look noticeably better, as seen
in some screenshots posted by mGBA's developer (endrift). A video has also been uploaded, showing the feature in action while playing F-Zero Climax (13x scaling, 3120x2080):
The high-resolution renderer is not yet available in stable mGBA builds, however it can be found in development ones (PC only). It's completely optional and will not be enabled by default: you can do so by looking at the "Enhancements" section in the settings (remember to set the renderer to OpenGL!). Keep in mind that by using a development build, you could find unexpected issues and poor performance, so it's still recommended to wait until a new stable version will be released unless you really want to stay on the bleeding edge.
https://mgba.io/downloads.html
https://gbatemp.net/threads/mgba-add...builds.539070/