It wasn't actually until Tribal mentioned it in #19 that I learned that FTE also supports rtlights, so I only have experience with Dark Places.
Basically, all the necessary information I found here:
http://www.nexuizninjaz.com/forum/Thread-How-to-Use-rtlights.html
You should definitely read the whole page, not just the first post, because at the bottom of the page you'll learn how to duplicate lights faster (something I wish I had done before doing these rtlights)! :D
There are a few things that aren't mentioned in the page though:
- If the map doesn't have an existing rtlights file, DP imports the map's regular light entities to be used as rtlights. Depending on the key/value pairs in your light entities, the conversion may be fairly smooth... or not so smooth, like for me:
When I opened Temple of Quake for the first time, some lights were super bright and especially colored lights were extremely saturated. I believe the problem occurs if you use bytes [0-255] instead of floats [0-1] in the field values.
For example, my map has quite a few fully red lights, so their [_color] keys have a value of [255 0 0]. Since DP seems to understand only floats, it interpreted the lights as 255 times as bright as a red light with a _color value of [1 0 0]. So don't be surprised if you're faced with overwhelmingly bright lights when you first fire up your map.
Also, worldspawn sunlights aren't imported since there is no actual point light entity for DP to read. I made my sunlights by making weak ambient rtlights with very long radii.
If your map has surface lights (featured in ericw-tools), only the one light entity that defines the surface lights will be imported; you'll have to create the rest of the surface lights individually for each of the desired surfaces.
- When I saved my rtlights for the first time, the file was saved for some reason in the following location:
C:\Users\<username>\Saved Games\darkplaces\id1\maps
For the longest time I had no idea where the realtime lighting was stored, until I finally found it.
However, I just tested saving an rtlights file while editing some random map, and this time the rtlights file was created in the same folder where the map was located (id1/maps), so if you can't find your rtlights file, look from those two places.
- You can create lightstyles (flickering/pulsing lights etc.) like you would on a normal level editor when creating/modifying rtlights, but you can't create switchable lights from scratch. You can only modify existing switchable lights. If the light is turned off at the start of the map, you'll have to trigger the light first if you want to see what the rtlight will look like when turned on.
Just found this one video too, where Romi, the creator of the popular Romi's rtlights file, tells about the creation process and history. Seems interesting:
https://www.youtube.com/watch?v=4EbvNVOVWlU
He even has a bunch of very recent Twitch streams where he does rtlights live, so seems like there's not a shortage of material!
https://www.twitch.tv/demonvein2003/videos/all
rtlights in FTE:
I have no prior experience with it, but you're supposed to install the in-game map editor in the "updates+packages" menu and then type "ca_show 1" on the console. I just tried it for a little bit, and it seems fairly intuitive and helpful.
If all of this feels overwhelming, don't worry: The best way to learn is to just jump in, start experimenting and learn by doing. :)