jmarsh wrote on 2020-04-19, 20:23:
BTW this really should be something upstream does, when a glshader is turned on, turn off the normal scaler. Combining a software scaler and a glshader seems like a recipe for unnecessary pain. In fact maybe it would be better to 'pretend' both use the same mechanism in the conf file just to prevent confusion with this and the need to turn off the one you're not actually using.
No because there are things scalers can do that shaders can't and vice-versa. Someone might want to use HQ2X/3X scaler with a CRT shader, for example.
The price of that kind of brittle flexibility (instead of say, making a two pass glshader for crt-hqx), is that you're going to get a bunch of 'spurious' bug reports that you can't do anything about because they're 'user errors' and the users are going to be pissed it's so easy to get it wrong.
In my particular computer (my experience only), besides the bugs, combing these two is asking for slowdown that might not happen if you only use either one apart - but that's likely because by computer is very very bad. Anyway, anecdotal datapoint: don't combine a software scaler with a glshader when your computer cpu/gpu are bad - two things that might be bearable individually might become horrible combined. In my case, even scale2x scaler combined with any shader is asking for sub 30 fps, while i can use pixel-perfect glshader with no scaler, go figure.