Can the layman tell the difference between running the latest version in opengl 4.5 and 3.3?

[invictius]

I've heard that 3.3 has a lot of features missing, but under what conditions would you notice that? Would it be bad enough to cause errors on a recent wad?

[Graf Zahl]

The main features not working under older OpenGL versions are the shadowmaps and SSAO.
Both of these do not even work that well performance wise on real GL 4.5 hardware, you need something a lot more powerful for that.

And since these features tend to be disabled on weaker hardware anyway it is unlikely you will notice just by looking at the visuals.

[invictius]

The main features not working under older OpenGL versions are the shadowmaps and SSAO.
Both of these do not even work that well performance wise on real GL 4.5 hardware, you need something a lot more powerful for that.

And since these features tend to be disabled on weaker hardware anyway it is unlikely you will notice just by looking at the visuals.

What functionality do you lose by going back to a version with opengl2 support on an opengl2 card? Also curious about what you miss out on 1.5 compared to 2.0, but I don't expect you to remember that far. Also do you still need opengl support in order to run gz in software mode? Someone in the zandronum discord said this was the case.

[Graf Zahl]

OpenGL 2 loses a lot, like shader based lighting, shader warped textures, per-pixel lighting. You may get the GLES renderer to work on some GL 2 hardware but it would be extremely slow. The main problem here is not lack of features - GL 2 had shaders after all, but the lack of performance that required less costly solutions.

And if you want to talk GL 1.5 hardware we'd have to go back to the stone age. GL 1.5 hardware was current when GZDoom started. GZDoom's renderer was very different back then. The main thing here is that the renderer got new features when current hardware allowed to implement them. But what you see now in GZDoom never worked on less than GL3 hardware