Category: News

I Can’t Talk Now, I’m Flying a Plane!

Traditionally, a pilot’s priorities are: aviate, navigate, communicate.

But that might not be true for X-Plane for the iPhone.

It’s real! And it pretty much is X-Plane – there really are OBJs and DSFs in there, as well as an ACF model, all tuned for the iPhone.

In the next few posts I’ll blog a little bit about the impact of doing an iPhone port on scenery development. The iPhone is an embedded device; if you go digging for system specs you’ll see that it’s a very different beast from the desktop. The porting process really helped me understand the problems of the rendering engine a lot better, and some of the techniques we developed for the iPhone are proving useful for desktop machines as well.

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Bad Alloc Crashes in 920 – Bad Timing

I just received a series of reports today that certain converted scenery will cause X-Plane to crash with a “bad alloc” error. Basically, this couldn’t have hit us at a worse time. The final 920 was cut a week ago. We physically can’t recut; Austin is on the road, and I am knee deep in it. But there is a possible work-around, and there will be a patch. Here’s the whole situation.

What is a Bad Alloc?

A bad alloc error is an error that comes up when X-Plane runs out of memory. This can happen for two reasons:

  • We have run out of address space – that is, there is no more virtual memory left, or
  • We have run out of page file/physical memory – that is, we can’t back that virtual memory.

The first case is by far the most common – you’d only hit the second if you are on Windows with a fixed-size (but small) page file. (Hint: if you have a fixed size page file, make it big!)

X-Plane can run out of memory for many reasons – everything that runs in the sim uses memory, and the amount used depends on what area you are in, what rendering settings you pick, and what third party add-ons you use. While I’d like to someday reach a point when the sim tells you gracefully that it’s out of memory, it will always be a fact of life that at some point (hopefully an absurdly high one) the amount of stuff you’ve asked X-Plane to do will exceed how much memory you have.

(If you are thinking 64 bits, well, that will just change the problem from a crash to a grinding halt when we run out of physical memory.)

We see bad allocs when there are too many third party add-ons installed (XSquawkBox is a particular pig because it loads every CSL on startup), too complex scenery, and it can also be caused by drivers not efficiently using memory. (This is particularly a problem on Vista RTM.)

The Bug

When X-Plane creates a curved airport taxiway, it allocates a temporary memory buffer to hold the intermediate product of the pavement. The size of that buffer depends on the complexity of the curve it is processing and a constant, based on the maximum curve smoothness.

In 920 I provided an option to crank up the curve smoothness in X-Plane. In the process, I increased that constant factor by 4x, which causes X-Plane to hit its memory ceiling on layouts that used to be acceptable. You’ll see this problem more often on:

  • Bigger, more complex layouts.
  • Configurations that were already chewing up a lot of memory.
  • Machines with less address space (Windows without /3GB, older Mac OS X operating systems.)

What really suckered us about this bug was that it comes in a form that looks almost the same as a driver issue we’ve seen with ATI drivers on Windows — we’ve seen strange forms of memory exhaustion on ATI when shifting scenery with high rendering settings. So we didn’t realize that this was something new until G5 users reported the bug (making us realize it wasn’t a driver thing).

What To Do

The bad news is that we can’t do an RC5 – we’re out of time. But – there will be a patch – relatively soon. This bug is on the short list for a patch to fix 920.

In the meantime, there is actually a work-around. By coincidence, some of the internal rendering engine constants are viewable via the “private dataref” system — basically a series of datarefs in the sim/private/… domain that I use for on-the-fly debugging. The dataref that matters here is:


If you load up DataRef Editor you’ll see it has a value of 12 . That’s too high. Changing it to 10 will allow otherwise problematic airports to load.

I will try to post a plugin in the next 10 days that sets this dataref to 10 on startup, effectively patching the problem. This will also limit the maximum smoothness of curves – but my guess is that if you see the crash (not all users do) then you can’t run on the max airport curve setting anyway.

Of course the next patch will contain a real solution: a more efficient memory allocation scheme!

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Engine Modeling and Autopilot

Two random and unrelated notes:

First, RC4 is going out as is, despite the engine modeling changes being incomplete. Basically we now have a more sane approach to the engines themselves, but no FADEC control. FADECs are on the short list for the next update. Sometimes we just run out of time – not every release can have everything.

Second, a note on autopilot customization – I am party to a fair number of questions about whether the plugin system can be used to make subtle changes to the autopilot logic. The answer is of course: no. If you really want something different for an autopilot, you’d have to replace the entire “top-half” set of logic and drive the flight directors yourself – in this situation you are responsible for:

  • All modes and mode changes based on conditions.
  • The actual selected flight envelope to achieve the desired AP setting.

But you are not responsible for driving the trim and yoke, which are done by you setting the flight director.

Why can’t you just override one specific behavior? It’s an issue of infrastructure.

Fundamentally, the autopilot only does a few certain tricks. If it were capable of doing customized behaviors, you’d already see it, in the form of a dataref or (more likely) a Plane-Maker setting. Basically there is no generality to the autopilot that we secretly have inside the code but don’t expose.

Will there be a more general autopilot someday? Maybe – I don’t know, I don’t work on that code. But the plugin system has always aimed to make it possible to do anything, but not necessarily easy. In particular, the plugin system doesn’t aim to make your development easier by recycling the simulator itself as a convenient library of lego bricks. In the end of the day, X-Plane is an application, not a library. If it were a library, that would be lots of fun for third parties, but it is not.

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This Blog is Not Tech Support

I don’t like to delete/reject people’s comments, but I do not want new users to find this blog, see tech support requests, and add their own, only to have them sit unanswered for, well, ever.

If you bought X-Plane from Laminar Research, the tech support contact info can be found here:


If you bought X-Plane in a store, the distributor will have their own tech support contact info on the box.

From this point on, I am going to reject requests for tech support that come in the comment box. If you need help with X-Plane, use the email or phone number found on the contact page above!

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Framebuffer Incomplete: I Need Your Help!

I believe I am getting close to a possible solution for the dreaded “Framebuffer Incomplete” errors – these error messages pop up when X-Plane starts, and you end up quitting.

If you meet these criteria, please contact me:

  1. You have an ATI card that has shown this error in the past.
  2. You can put on the latest Catalyst drivers. (I know a lot of you have put on older drivers to work around this.)
  3. You can run X-Plane 920 RC2.

If you’re in this crew, please email me at my XSquawkBox email address!

The rub is: despite having four machines with ATI cards, I never see this error. So I need to send you a build to get close to a fix!!! Let’s swat this bug for real!

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WED 1.1 Feature List

As 920 beta finishes up, I am working on some WED features. Future WED updates will be small and more frequent; I think it’s more useful to get at least some features into WED quickly, rather than holding them until I have a huge update.

So this list is short – that doesn’t mean that other features won’t happen – they just won’t happen as soon. In particular, I am very aware that WED needs better taxiway sign editing and better polygon editing. Those will have to wait though.

WED 1.1 will provide overlay editing. WED will not be a replacement for overlay editor – Marginal has done a really great job with his tools. However, having overlay editing in WED will allow people making airports to see complete apt.dat 850 data and overlay data at the same time. This is particularly useful for authors making custom scenery where the apt.dat format is augmented with custom DSF overlay pavement and lines.*

WED 1.1 will have 3 features:

  • Ability to edit these DSF overlay types: object placements, facades, forests, object strings, draped lines, and draped polygons (both tiled and textured with ST coordinates).
  • Very limited preview of those types. I know you will be able to see the texture for a draped polygon for orthophoto placement. I do not know if I will even have OBJ preview in 1.1. Editing will not be WYSIWYG. It will be more CAD-like.
  • Import and export of DSF overlay types to DSF overlay files.

Note that while roads and beaches are technically allowed in overlays, they are not on the list. The reason is that right now both of them require elevation data in the road and beach itself. Since WED doesn’t have a base mesh, it can’t sanely provide this information.

Eventually we will have some way to “drape” roads – at that point it will make sense to provide WED road editing too. But let’s not delay at least some overlay editing that long!

I don’t know exactly how long this work will take – my rough guesstimate is about 2 weeks. But…that depends on my working on WED for two weeks straight without interruption!

* Every type of element in apt.dat can also be created with custom-provided artwork and an overlay DSF — draped polygons for taxiways, draped lines for taxiway lines, object strings for taxiway lights, etc. The idea is to provide a way for authors who want to extend realism beyond the scope of apt.dat 850 to insert custom artwork. Apt.dat 850 is not a modeling format, so you cannot provide PNG files with it.

If you look at the LOWI demo area, you’ll see that some of the pavement in that layout is in the apt.dat file, but some pavement is in the DSF overlay. Creating this demo area required a bunch of DSF2Text hacking by Sergio and myself. With WED 1.1 it will be possible to do this completely using WED.

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902 Is Dead (Long Live 920) – Languages

We’re about to do something strange: any time now, Austin should announce 920 beta 1.

But what happened to the 902 beta program?

The answer is simple: it turns out we don’t need it.

Both 901 and 902 were tiny releases whose sole purpose was to add new languages to X-Plane. (901 added French/German, 902 Russian). The idea was to get our foreign distributors a localized version of the sim faster than we could do the next major patch.

Well, 920 is here, and the Russian port is still being debugged, so 920 will contain Russian and also a huge host of new features. There will never be a 902 final; simply update your beta to 920 when it’s out – any tiny changes in 902 are baked into 920.

Don’t Panic

As always, my advice for beta 1 is: don’t panic. Remember that we are a small company, and thus we have a small number of computers between all of our employees. The first few betas usually involve one or two serious bugs (the sim explodes and sets your computer on fire, etc.) that only happen on the one hardware configuration none of us have.

If you are a user, consider waiting for a later beta, or upgrade a copy of the sim.

If you create third party add-ons, please get a copy of the beta early and start filing bugs! It is much easier for us to fix compatibility bugs when we get the reports early.


A number of users have offered to help translate X-Plane. With 920 we finally have the “new” localization infrastructure in place; I will finally be able to get users started on this process.

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Drivers and Builds To Try

For those who posted comments, sorry it took so long to moderate them – for some reason my spam filter decided that notifications of comments are, well, spam, so I just found them now. I should have known people would have jumped into a Vista-bashing thread. 🙂

There is an X-Plane 9.02 beta 1 posted – like 901 we’ve been pretty quiet about this, but you can get it by enabling “get betas” and running the X-Plane updater. Please give it a try. Like 901 it is a small change for the purpose of localization, but it actually has an interesting feature pair:

  • True-type fonts and
  • Unicode-aware.

This is part of some rework we did to provide better language support. So…you should be able to run X-Plane no matter what weird characters* are in your folder names, name your airplanes funny things, and see diacritical marks. 902 uses a font that provides all of the Latin and Greek/Cyrillic code pages.

Also I have heard reports of improvements based on drivers:

  • nVidia has 175.16 drivers out and they apparently address “stuttering” issues. The stuttering issue has been on my list to investigate because it happens under Windows but not Linux. If you have stuttering performance on high-end NV hardware, particularly with forests and Windows, please try 175.16 and let me know how it goes.
  • ATI has released Catalyst 8-5. Catalyst 8-3 and 8-4 were causing “incomplete framebuffer” errors for some users, but I was unable to reproduce it (after spending a good day trying to jam Windows XP onto an iMac already crammed with Windows and Linux….yet another episode of a Tale of Three Operating Sytstems). Anyway, at least one user reported the issue as fixed in Cat 8-5, so if you are having problems, please try the new driver set.

As always, bugs in the X-Plane beta should go to our bug report form, on the X-Plane contacts page.

* You might accuse me of being American-centric in decrying diacritical and greek letters weird – but the truth is I am computer-centric…anything that is not in the original ASCII set is weird. 🙂

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901 – Stealth Release

901 is out now…basically it’s just 900 + French and German localizations. Also a few minor tweaks:

  • We added a few datarefs and commands by request – check DataRefs.txt.
  • The plugin font size is back to 6 pixels, like v8. It looks a bit ugly now, but we’ll put a new font in place soon. The important thing is: 6-pixel fonts for v8 and v9, so one plugin can operate everywhere.
  • A few plugin bug fixes – see the SDK known bugs page.
  • Linux won’t complain if your disk is mounted as iso9660. Since the v9 final disks are all mastered as ISOs and not UDF, asking you to mount them as UDF is asking the impossible.
  • If you have a demo install, it will add the word “Demo” to its name in the startup screen. This is to help users with more than one install identify which one they are running.

If this all seems minor and tweaky, well, it is. The main point of 901 was to get the localizations in. In the future we’ll have a feature patch that brings new airplane features in and other cool stuff.

901 is freely available using the X-Plane web updater…the download size is only about 14 MB.

Finally, I’ve posted all new DVD installer/updater/web demo installer apps – version 2.04 localizes to French and German too.

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901RC1 Already? Try it!

Well, the paint is barely dry and we already have an X-Plane 9.01 RC1. Here’s what’s going on and how you can try it.

9.01 is the first of what may be a few small internationalization and localization patches. 9.01 adds German localization and updates the French strings. 9.01 also has a handful of very minor bugs; Austin will probably post the bug list shortly. 9.01 is already RC because the code changes are really minor.

After 9.01 we’ll do another localization patch (probably in the next month) that will include unicode and true-type font support. That build (902? 905? Who can guess what number Austin will pick!) will probably have a formally named beta because the unicode changes are extensive.

900r3 is still the latest final build and it’s what you get if you update your copy or run the web demo installer.

To get 901r1, go to the updater options and check “get betas”; update your sim and 901r1 will be downloaded. Please try it!

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