This uses the new spotlight actors in GZDoom.
Preview: https://my.mixtape.moe/dfnlrl.m4v Click and your browser should just play.
Requirements
Needs a release from at least 2018-02-10.
Setup
Assign a key to toggle the flashlight in your controls menu right at the bottom of "customise controls".
Under options, you can select Flashlight and customise it. Options take affect next time it switches on.
Known Issues
There is some jitter in the changing of location and orientation of the spotlight. Using the target pointer of lights doesn't solve the jitter and is not suitable anyway as the light should emit from the actor's "shoulder". I'm not sure this will ever be fixed or can even be fixed given the way ZDoom updates actors. You can stop it right now by turning off rendering interpolation off but then you only get 35 FPS. Suggestions very welcome.
Releases
12 Feb, 2018
https://www.dropbox.com/s/kz4tp5nhog772 ... 2.pk7?dl=1
- You may now choose a location for the light to emit from.
- The light now reacts to crouching.
- Multiplayer now supported. Settings are shared.
https://www.dropbox.com/s/vbwsji4l6e85m ... 0.pk7?dl=1
License
Unlicense. (That means do what you want, no credit needed.)