[UPDATE] mGBA adds high-res scaling in its latest development builds
'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 & Switch only, see update below). 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.
UPDATE (27/5/19): Hi-res scaling has been added to the latest Switch builds. The feature is highly experimental on this platform and it could suffer from both graphical glitches and slowdowns. Code optimization is still being worked on: due to this, the developer kindly asks all users to not file bug reports related to poor performance.
Hi-res is supported on Switch in latest builds. I’m going to sleep, I’m expecting to wake up to 20 bug reports of various things breaking (or just being slow—don’t file those ones please, I’m working on it).
— endrift 🏳️⚧️ (@endrift) May 27, 2019
Source