Quote Originally Posted by flamaros View Post
Why it's better to use a viewport instead of just switching everything to the opengl render?

I develop an application for Android, iOS, Windows, Mac OS X and we plan to migrate it to Qt5.x in a near future. On platforms like Android or iOS opengl is the native graphic system.
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Because the gl renderer is of lower quality than the raster one. And (I think) it won't work on Qt5 anyway.