Light Sizes – A No Win Situation

Update: We are going to release a new release candidate (10.21 rc2) tonight that puts the light sizing back to normal, while still fixing the SSAA bug.  This will have two effects:

• Runway lights won’t be as bright as in the RC.  Sorry guys, we will get this fixed, but clearly it’s not something that I should try to change by jamming a code change in at the last minute.
• Airplane lights will look the same as they do in 10.20 and 10.11.

The rest of the original post follows…

I jammed a change into X-Plane 10.21 rc1 that maybe wasn’t such a great idea: in X-Plane 10.21 the light billboards get bigger when your screen resolution gets bigger.

The idea behind this change is that the percentage of lit pixels in the night scene should not get smaller when you go to a bigger monitor – if they do, then the night scene looks dark.  In X-Plane 10.20 (and 10.10 and 10.05!) the billboard sizes are fixed in pixels – in a bigger monitor they tend to be tiny little dots, potentially harder to see.

This change makes a mess of aircraft lighting, and almost certainly needs to be changed (again) for an RC2.  But the choices aren’t good.

• If we keep the old behavior (light size is constant in pixels) then authors have a lousy choice: make the lights too big in a small window or too small in a big window.  There’s no way to get your billboards to look good on a laptop and a 1440p monitor.  This is what authors have been living with, and it’s lousy.  If you make a plane, you know that your lights only look right if the user has the same screen resolution as you – something you just should not assume.
• If we take the new behavior, what size should the lights be?  We have to pick a screen size to use as “official” from 10.20.  In rc1, I picked 1024 x 768 – that is, the smallest resolution we support.  This choice makes the runway lights look good, but virtually all airplanes are going to have lights that look too huge.

So I am considering one of the following choices:

• Match the 10.21 lights to 1020 at 1080p (or some other intermediate resolution), in the hope that most airplanes will look good on average.
• Revert the change entirely (and keep only the fix for 4x SSAA) and solve this in 10.30.  This isn’t good because (per above) authors are again stuck with the airplane only looking good at one resolution.  But at least in 10.30 we could do something more clever (e.g. different behaviors for old and new airplanes or who-knows-what-else).  Alex is still out of the country, so the thought of punting this until he can look at the results of some of the choices is tempting.
• Apply mixed behavior (e.g. different math for scenery vs. airplanes).  With anything “clever” like this, we risk the equations getting complicated, with too much fine print for authoring.

Anyway, I think it’s 95% likely we’ll cut an RC2; I’ll post something when we pick a strategy.

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.

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