Please help me understand how the glow works in this texture

[KevKiev]

More of a general texturing than a Gimp question (with a bit of mesh editing thrown in), but I'm hoping y'all can help me understand what's going on with something.  It's complicated (to me anyways) but hopefully I can explain clearly.  I asked about the "glow" rather than the "glow map" for a reason.  (Que suspense... or not).  I apologize in advance if I'm including too much but, in the circumstances, I'm thinking too much info is better than not enough.  (You might end up disagreeing with that.)

My project is to retexture a radio in the game Fallout 4.  I'm currently just muddling around, watching and reading tuts and tips and testing stuff on practice textures, as the more I learn the more I get a clearer idea of what I want to accomplish.  The radio is nothing special but, and this is the point of my post, its dial lights up when the player clicks it to turn it on.

I mentioned my current playing around with textures 'cuz some of the images I'll be posting are textures from the game files themselves but others from a high resolution retexture of the radio that I downloaded and am using for my practising (that's where the blue colour in some of the images comes from).  I'm doing that mainly because some of the game's default textures are of lower quality and simply aren't as useful to make my points here, but also because, although the diffuse maps are identical apart from the level of detail, there is a difference between the glow maps and that added to my confusion.  (Eventually, I hope to learn enough about enhancement techniques to jazz up the default textures to be as detailed as the ones I downloaded.) I'll call the game's default files the "vanilla" ones and the downloaded ones the "mod" or "modded" ones.  Hope I'm not oversimplifying, but I don't know how many of y'all are gamers and familiar with the nomenclature.

ANYWAYS... first some general stuff.  Here's an image of the radio's vanilla diffuse map.  Notice that there are 2 dials, the darker one in the "main" part (I'll call this the "main dial" later) and the brighter one in the bottom right (the "secondary dial"). 



The 2 dials threw me for a loop at first, but I think the main dial is the texture used when the radio is off, and the secondary dial is used when the radio is turned on. (I THINK... this point is actually the crux of this post.)  Like so:




Here's an image of the secondary dial portion of the diffuse, enlarged mainly to point out the various "cutouts" in the texture around the words and numbers.  (Afaik, texture mapping is eliminated from those areas).  The image is of the modded diffuse but the vanilla diffuse also has these cutouts but iis of such low quality it's really hard to capture in a screenshot and I'm fairly sure the author of the download just upscaled and enhanced the vanilla file anyways.  In particular, notice how some of the cutouts are kinda messy: E.G. the one for "600" in the top left is pretty accurate but the one for "55" in the bottom right doesn't line up with the actual number very well at all.  (I don't think this is the mod author's fault as, again, I think he probably just upscaled/enhanced the vanilla texture.)



Here's an image of the vanilla glow map.  It appears to only include the secondary dial:



The secondary dial portion of the vanilla glowmap, enlarged: It appears to have no cutouts at all:



Oddly enough, the modded glowmap does have cutouts.  It actually looks like he made a glow map out of the diffuse, as it includes areas of the diffuse not shown in the default glowmap and has the same cutouts in the secondary dial as does the modded diffuse. Note that none of the non-blacked out textures, aside from the secondary dial, glow in the game.  I think he could have also blacked out those portions. (The "Radiation King" logo doesn't appear at all.  I think the game developer included it in the texture but ultimately made the mesh such that it doesn't use the logo.) 

An image of the modded glowmap:



And an enlargement of the secondary dial portion of the modded glow map, to show the cutouts better:



Now for some specifics.

I coloured parts of the diffuse map blue, including the main dial, and saved those textures into the game files (which would override the vanilla ones) but, when was in-game, the radio had all my colours except it would revert to its original brown when lit up.  I tried all sorts of thing (coloured the secondary dial, coloured the glow map, deleted the glow map completely) but nothing changed.  I finally put that aside and worked on other stuff, including editing the mesh file in nifskope to make it a unique game item, with pathing to my (coloured) textures so only that mesh would use my textures (if I hadn't done that, any other model that used the same mesh would also use my textures, which I wanted to avoid).  To my surprise, when I loaded the game, the dial lit up in glorious blue when I turned the radio on.

I'm guessing, but only guessing, that this is the portion of the edited mesh records (shown via Nifskope) that's responsible for that sudden glow:

 

It's a wildly uneducated guess, mind you, and one I make really because it's the only portion of the mesh I saw that had "Emissive" data, which I believe generates a glow quite apart from any glow map.  I'm also (wildly) guessing that, for whatever reason, until I edited the mesh to change the "source texture" from the vanilla one to my coloured one, it was drawing on the vanilla diffuse (and its brown secondary dial).  I mean, where else could the brown have come from?  Remember, all other parts of the radio were using my recolouring, including the main dial portion of the diffuse.

Another thing I noticed when the dial lit up was that its words and letters suddenly became smudged.  I concluded that the "on" function somehow indeed triggers the secondary dial portion of the diffuse.  On closer inspection, the smudges seemed to correspond with the accuracy of the cutouts on the secondary dial.  The 600 was reasonably clear (i.e. black numbers) while the 55 was very blurry.  And there was a smudge underneath the 30 and 35 in the inner portion of the secondary dial.  All just like the cutouts in the secondary dial portion of the diffuse.

Here's where things got really weird. I'd concluded that the secondary dial was responsible (at least partly) for the glow when the radio was turned on, perhaps because of the mesh settings shown above, but what I couldn't figure out was: "what use does the glow map serve"?  So I did some random testing including completely clearing the secondary dial portion of the glowmap and loading it into the game files, i.e. so the glowmap being used looked like this:



And there was no difference!  In game, the turned-on radio still glowed the same blue, with the same smudgy spots.  There was also no difference whether I used the modded glow map (i.e. cutouts around the numbers & words on the secondary dial, just like on that portion of the diffuse) or the vanilla glowmap (no cutouts).  So, yeah, why is there a glow map in the first place?!

ANYWAYS... whew.  Unfortunately, when I focus on this stuff too much I sometimes get a bad case of information overload and logical thought starts to blur.  I think I'll leave it there except to actually ask a few questions.  What I'm hoping is that, although a lot of this makes my head start spinning, I've explained enough to get some guidance.  So...

1.  Can anyone explain, even in broad strokes, what the heck is going on with the glow?  I was puzzled enough by 2 separate dials being in the diffuse as I had no idea that meshes could draw on different portions of a texture map to texture the same part.  But it appears that's indeed the case.  Still, I'm not sure how exactly that works.  I didn't see anything in the mesh records that jumped out at me to help explain it.  (Although I'm an equal noob with meshes as I am with textures so that's not saying much.)  Am I on the right track with my guesses about how all this is working?

2. Specific to my project, I'd like to (i) spruce up the existing dial so that, when it's turned on and glowing it looks (except for the glow obviously) exactly the same as when it's turned off. I.E. So the numbers & letters are just as readable and not all smudgy like they are now when its turned on; or (ii) completely redo the dial so it doesn't look as cartoony (although that does have its charm).  Something like this (from Deviant Art, this model is a huge inspiration for my project):

* okay, looks like I'm over the image limit for a post.  But here's a link if you want to check it out.  It's just a more "normal", and quite elegant, plain light-coloured dial with much finer lettering and numbering*

But, crikey, if Ihave to make cutouts to make details show up when there's a background glow, it's hugely daunting to think of using such fine numbering/ lettering.  That said, it's wild how much I'm learning every day and part of me thinks that there's just a tool or technique I need to learn to accomplish this.  And, as well, the whole thing with cutouts weirds me out a bit - I guess the black lettering & numbering on the dial isn't enough to "block" the glow and you have to actually clear that portion of the texture map?  Am I even on the right track as to how these cutouts work?  And what if you want something other than black lettering & numbering?  (That last part goes beyond precisely what I'm looking for as I don't have any plans for coloured numbers or letters.  Still, I'm curious and I'd love to understand as much of this as I can.)

So the second question is kinda related to the first: how does this all work in relation to the cutouts and how they seem specifically to relate to what appears on the dial when glow is activated?

And, finally

3. Why was there no difference when I cleared the only portion of the glow map that had anthing but black?  If the glow comes exclusively from those mesh settings shown in that one image, surely the game developer wouldn't have bothered creating a glow map in the first place?  But it made no visible difference so... but... (aargh... where do I even go from there?)

And that's it.  I hope at least some of y'all made it this far.  I would be MUCH obliged for any assistance.  If you need any further info or clarification, please ask.

THANK YOU!

---

Oh, one more thing that I didn't think was relevant but... maybe?

In Fallout 4, the game developer introduced files called "BGSMs" or "material" files. The way I understand it, they're files that essentially act as a "middle man" and map textures to meshes. They allow single meshes to use multiple texture sets (for example, there can be one mesh for a particular armor, but it'll map to different textures so that officers wear black and subordinates wear orange). Again as far as I know, those files will override any single textures that are placed in the game and with which they conflict. However, when I tested the radio in-game, I'd already edited the relevant BGSM to use my (coloured) textures so there wouldn't be any conflict. As well, where the mesh file pathed to the BGSM (which pathed to the coloured textures), it was in places where you'd normally expect textures to be. I.E. there was no "emissive" data in those portions of the mesh records or anything else that looked peculiar.

Hope that made sense. If it would be of any help, I could post images of Nifskope screenshots showing the exact records that pathed to the BGSM.

[mholder]

I am not familiar with fallout or how the engine works, but usually 3d models have separate textures to deal with how light behaves with it.

For example, the diffuse texture is the base colors.  Other common textures maps include things like specular map for what parts are shiny in the light.  Normal maps for how light is reflected depending on the angle, etc.

An emission map would show where light emits from, and I suppose in this case is a black and white texture, where the closer to white the more light emits, like a mask.  In your screenshot 'emissive color #ffffff00' looks like a hex value for pure white, normally written #ffffff. The multiple could be the factor.  For example 1.5 would be 50% more.

But I really don't know or have an experience with this engine or what Nifskope is or generally what you are asking.

I think you should try to focus on what you are asking, and you will probably get a better answer.

edit--The vanilla glow texture has no transparency. Your version does. Maybe that is the problem. Maybe instead of a 32 bit image is should be 24. Also, it might should even be a 8 bit black and white. Think of the glow texture as a mask. The white areas are where the light comes from, and if follows the same UV coordinates as the diffuse texture. And the setting #ffffff00 is the color of the light.

[KevKiev]

Thanks

Yes, that's my understanding of the emissive settings in Nifskope (a freeware mesh editing tool) -the multiple determines the intensity of the glow.

I didn't want to bring normal or specular maps into things, as they have no relevance here.

In regards to the glow map, I understand generally how glow maps work but, here, neither the vanilla nor the modded version made any visual difference. And neither did clearing the texture from the entire white area. Any way you slice it, the glow map seemed to have no effect on the visible texture in the least. I guess "cutouts" are better referred to as transparencies.\

Edit: on further testing, blacking out the entire emissive area of the glow map (if that's the right term i.e. the entire map is solid black) and even deleting the glow map completely had no effect. It really seems that the glow effect is coming solely from the secondary dial portion of the diffuse, using the emissive colour/multiple settings from the mesh and the glow map is playing no part in things at all.

As well, blacking out the entire secondary dial portion of the diffuse resulted in the radio showing the exact same dial turned on as turned off, despite the glow map being active. No glow and no smudging of the letters or numbers.

So... at this point my surprising (to me anyways) conclusion, based solely on my observations from trial and error, is that:

1. The glow map has absolutely no impact on the radio model and could have been excluded. (Odd but considering there's a multitude of bugs in this game, maybe not out-of-this-world surprising.); and

2. When the radio is activated, both the main dial and secondary dial portions of the diffuse map come into play. The secondary dial provides the glow, but it acts like a layer underneath the main dial portion. In effect, it is the glow map. The purpose of the transparencies in the secondary dial portion of the diffuse is to ensure that the numbers & letters remain legible by preventing emission from those areas so the numbers & letters on the main dial portion look like they would with no glow at all. But that makes it critical that those transparencies accurately line up with the features of the main dial. Where there's inaccuracies, the numbers & letters on the main dial portion of the diffuse are able to block some of the emitted glow from that underlying (secondary dial) layer but only to a certain extent. Some glow still gets through and the result is the smudging around the numbers and letters on the main dial that don't have precisely matching transparencies. (And, in other places, too much glow gets through.)

I know I'm a noob, but it really seems to me that this is what's happening. It's the only thing that makes sense to me given the characteristics of the main and secondary dial portions of the diffuse, the characteristics of the glow map (both modded and vanilla), and what I'm seeing in my tests. Of course, I would still welcome comments from anyone else who would like to chime in.

Edit: 3rd conclusion

I'm guessing that another way to manage the glow effect on this model would be to path the mesh records that contain emissive data to the glow map rather than the diffuse, which would render the secondary dial portion of the diffuse as useless as the glow map is currently. And then the glow map would have to incorporate the same (but more precise) transparencies currently in the secondary dial portion of the diffuse. But at this point that's just a guess and, even if correct, might simply be a "six of one half dozen of the other" alternative.

[mholder]

You should find a forum specifically for that engine.

[KevKiev]

Well, nah... I hear ya, but at this point I'm comfortable enough with my conclusions that I think I'll be closing the lid on this issue (barring any revelations that might be posted). Not that I wouldn't like to nail it down even more firmly, but I have sooo much other stuff to focus on (i.e. figure out) for what I want to do with this project that I'd rather spend the time elsewhere. Cheers