Brightmaps lights zd_extra and gzdoom pk3s

[MrDowntempo]

So, pardon the newbie question, and I wasn't really sure where to post this question. But here goes:
Although I've played doom off and on since near its initial released, I've really started getting back into playing doom again over the last few years when I started watching Doom Mod Madness. And this is what got me into using gzdoom. Now gzdoom comes with some resouce pk3 files: brightmaps lights zd_extra and gzdoom. While I've sorta figured out what they are, I'm not ever sure if and when I should be loading them. I get that zd_extra has copyright infringing assets, but... since I own the original doom game, should I add it whenever I play? Same with brightmaps and lights? I get that they have something to do with modern light effects on old textures, but ... do I need to load them myself when I play the original maps? What about when playing a wad that uses the original textures? What about playing an original map, or a wad with original textures but I also add a HD texture wad, do I still ever need to add those wads to my load order? And is gzdoom.pk3 something that I ever need to mess with? I've never found a clear full explaination of when I need to bother with those pk3 files and how.

Thanks for the help!

[wildweasel]

Zd_extra loads itself automatically and exclusively contains resources derived from copyrighted assets. It's separate so that folks who are distributing new games can easily remove the copyrighted assets for free distribution. The others can be loaded manually, since they add extra effects that may not be desired.

[phantombeta]

Both gzdoom.pk3 and zd_extra.pk3 are always loaded automatically by the engine. Brightmaps.pk3 and lights.pk3 can be loaded manually, but the preferred/easiest method is to load them by checking their respective checkboxes in the IWAD selection dialog:

[MrDowntempo]

Ah, I tend to use a different launcher than that one. Rockerlauncher2 is my preferred one. Is there any rule of thumb about which maps or wads it's ok to load lights and brightmaps on and when it should be avoided? Meaning, if I use mods with wholey new textures should I keep them off, or does it matter what textures I use with them at all?

[Graf Zahl]

In general, it should be avoided if some mod replaces sprites or modifies thing with Dehacked so that content and definition no longer match. A general rule of thumb is hard to give, because it heavily depends on the content.