OK, I'm posting this as something of a PSA for anyone else that might be looking for this information. It took me several hours, many different shader packs, and a lot of semi-useless videos before I finally found one that actually was helpful. If you want to change the torchlight colour, that would be the video to watch. At least, for now. This post is basically a text-only version of that video for the benefit of those (like me) who have poor internet connections and/or don't like watching videos to learn about coding. The video has a bit more detail, but it is specific to a single shaderpack.

Technical info: My base copy of minecraft is vanilla 1.10.2 (as in no mods), to which I have added Optifine Ultra. That's all one needs to use shaders.

There are a ton of shaders out there, and I can't provide guidance on all of them, but between the video and this info, most people should be able to figure out where to look, at least.

Basically, to install a shader you put the shaderpack in /roaming/.minecraft/shaderpacks/

1) Once you have a shaderpack working, you will probably notice that many of them set the colour of torch light, as well as lanterns and everything else makes light a terrible shade of orange. Some people like it, some list it as a perk, I don't like it. I don't begrudge others their orange worlds, but I'd like to have the benefit of shaders without the colour scheme.

2) Now turn off the shaderpack again by going into the shaderpack selection screen and selecting "Off" or "Internal"

3) Find the shaderpack. It should be located at /roaming/.minecraft/shaderpacks/NameOfShaderHere

4) Open the "Shaders" folder and you should see a bunch of files entitled composite.vsh, composite1.vsh, composite2.vsh, composite3.vsh (and a lot of other ones, some with fsh file endings.) These are the files we are interested in.

5) Within these files, we need to find the variable that sets the torchlight colour. I use Notepad++ for this, but any straigh text editor such as notepad should work just fine. Do not use wordpad, Word, or other word processors, as they tend to mess things up.

In SEUS, you are looking for a variable labeled:

 colorTorchlight = vec3(1.00f, 0.22f, 0.00f); 

For me, this variable is set in composite1.vsh, composite2.vsh, and composite3.vsh, so you will need to find all three of them.

In KUDA you are looking for

 vec3 torch_Color = vec3(1.0, 0.64, 0.4); 

This was located in just a single file, composite.fsh.

For Werrus, you are looking for

 vec3 torchcolor = vec3(1.0,0.25,0.0); //RGB - Red, Green, Blue / vec3(0.6,0.32,0.1) is default vec3 torchcolor2 = vec3(1.0,0.45,0.0); //RGB - Red, Green, Blue / vec3(0.6,0.32,0.1) is default 

6) Change the numbers to indicate a colour more along the lines of your liking. The numbers are all RGB and the ones I have looked at are 0 is none and 1 is high, so numbers between 0 and 1 are ideal. I like something a bit closer to white, so I use the following:

SEUS: colorTorchlight = vec3(1.00f, 0.80f, 0.70f); KUDA: vec3 torch_Color = vec3(1.0, 0.8, 0.7); 

7)Once you have made the changes, save the file(s) and go into Minecraft, and choose the appropriate Shader and see if the light colour has changed. Assuming you have made the changes correctly, you should have a new colour in areas that are lit up with torches. I encourage you to experiment to find colours that you like.

While I can't guarantee anything, I suspect that most shaders use the same sort of method, so searching through their files for color, torch, torchlight, and similar names will probably find the variables you are looking for.

I hope this is helpful, and have fun. 🙂