increasing rendering resolution didnt make visuals better than i expected.
main reason is lack of scaling algorithm. distant objects loose its details and pixelifies.
bicubic scaling or something similar may be a solution.

Bilinear can be also a good option

Unfortunately you'd have to do it manually since gl11 doesn't provide automatic bicubic mipmap generation. Otherwise I would gladly make a pull request but I'm not experienced enough to do that. (It'd be like a few lines of extra code in a Vulkan implementation)

Lanczos will work very well too.