Edit: Normally I label the overly technical posts as being for a target audience, but I did not this time.  My bad — this post is really only of interest (and will only make sense) to serious 3-d modelers – the advanced airplane and scenery nerds!

The brightness of specular hilights is out of sync between HDR and non-HDR mode in X-Plane 10.11.  This wasn’t intentional – it’s a bug.  10.20 will fix this; specualr hilights will have the brightness you see in non-HDR mode (which we think is more like they were supposed to work*) but the tinting of HDR mode (non-HDR mode was overly red in 10.11).

I get a lot of requests for ‘hardness’ control – that is, the exponent that controls how wide a specular hilight is.  We’ll get this feature eventually – it’s too important to ignore.  The main delay in having this feature is that X-Plane uses a deferred renderer, so the specular exponent has to be stored in the G-Buffer somewhere, and storage is tight.

For similar reasons, it is very very unlikely that we’ll ever have RGB tinting of specular hilights.  Doing so is 3x as expensive in G-Buffer storage, and we need that storage for other features.

* That is, unless we discover that non-HDR mode looks spectacularly bad in some cases, in which case we may have to push things a little more toward how HDR was.

About Ben Supnik

Ben is a software engineer who works on X-Plane; he spends most of his days drinking coffee and swearing at the computer -- sometimes at the same time.

16 comments on “Look, Shiny!

  1. Hi Ben,

    Love your blog, hit it every day since becoming an X-Plane user a couple of weeks ago. Even though I don’t understand half of the stuff you are referring to (and I am an IT techy!) it’s a ally good read and certainly keeps the user experience fresh, the fact that one of the guys writing the code is actually communicating on an almost-daily basis to his customer-base is absolutely brilliant.


    I also appreciate your direct and sometimes-sarcastic style – why the h3ll not?!?!

    Anyway, cheers – your blogs are VERY much appreciated. Even tit-bits like the above. I’ve come home from a hard day at work today and I’ve got “Look, Shiny!” to read – genius.

    All the best!



  2. Ben — By RGB tinting of the specular highlights, I’m presuming that would be initially found when X-Plane loaded an object as part of the OBJ8 format. If I may be so bold, such feature would be extremely valuable in terms of material simulation. You’d get a lot of bang for the memory buck, particularly in representing metals. It’s worth keeping under consideration. Like shadows, it could be something that wasn’t always “turned on.” Any hope?

      1. To be sure. But aren’t G-buffers getting bigger all the time? Where will we be in two years? Not quibbling. I guess it depends on how easy RGB tinted specularity is to code, Ben. Processing it might be a bridge too far now, but when we have the advantage of 20/20 hindsight, it might be seen in a significantly different light. No pun intended. Thanks for not closing the door.

        1. LOL..this cracked me up: “But aren’t G-buffers getting bigger all the time?” Yes, but that’s NOT necessarily a good thing. 😉

          Seriously, yes, in the long term we can expect the cost of the G-buffer to go down as we get faster busses, more ROPs, more VRAM, bla bla bla. But increasing the size of the G-Buffer is a fairly drastic and non-incremental thing – it’s a system-wide tax, so I’m not looking to push it and push it and push it. The _coding_ of specular tinting is pretty trivial – it’s the G-buffer cost that’s an issue. (And once we have it, we’ll end up with specular-tinted content.)

          I am also _not_ convinced that specular tinting is the best use of G-Buffer space within the bigger scope of ‘materials’, something that unfortunately G-Buffers don’t handle with a lot of grace. I want to understand what else we want to spend g-buffer budget on before spending that budget.

  3. I have no idea if this is what you are referring to as “RGB tinting of specular highlights” but will there one day be real reflections on materials (instead of just being shiny)?

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