Category: Development

Two “Gotchas” Developing Plugins

These both come from third party developers – one I was aware of and one was completely new to me.

The Debug Heap Is Slow

Veteran Windows C++ developers know this, but if you don’t spend a lot of time with MSVC, this might be new.

The default configuration of MSVC is to force use of the debug heap when the debugger is attached; this applies even to release builds of binaries that aren’t yours.

What this means is: if you do nothing else but start your plugin “inside” X-Plane, X-Plane will use Microsoft’s debug heap.

We avoid doing this internally because it is really, really, really slow. The debug heap provides some great tracking for finding memory problems, but the cost is really, really slow load time.

The fix is simple: add _NO_DEBUG_HEAP=1 to the environment variables for your debugger. You can do this in the control panel as shown in the linked article, or you can add it to MSVC’s debugger properties.

Other Things To Go Fast

As a side tangent, when debugging a plugin, find ways to load X-Plane faster. A few things that can help:

  • Turn off AI aircraft.
  • Pick a simple aircraft to fly (e.g. not the 747).
  • Go somewhere without scenery (or without much scenery, e.g. PMDY).
  • If you have to have scenery, turn 3-d all the way off.

My Plugin Won’t Reload

We receive periodic bug reports that plugins won’t reload on Windows. This is miserable for you as a third party developer – it means rebooting the sim instead of just reloading your plugin. But why does it happen?

I thought we had a bug, but a third party developer found this:

I did searched the registry for the names I’ve used for X-Plane 11 folder and found this items at
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windws NT\CurrentVersion\AppCompatFlags\Layers

Each name used was included there with “$IgnoreFreeLibrary<win.xpl>”
value, after removing them and restarting X-Plane I got able to compile the plugin using the names again.

I have not found any official Microsoft documentation on this, just a lot of ranting from really annoyed programmers who want to know why the hell Microsoft would do this. If anyone has better Google-Fu than me and can find official docs, please do share. So what follows is my wild speculation of what’s going on.

In some old version of Windows, FreeLibrary probably didn’t actually (or immediately) free a DLL under certain circumstances. Application developers then wrote buggy apps that relied on this behavior, e.g. they freed a library while it was in use and their app didn’t crash.

Microsoft updated Windows and made FreeLibrary do what it says on the label, always, and old buggy apps started crashing left and right.

Microsoft, being Microsoft, did not say “you app developers are idiots, why don’t you go rewrite your buggy apps”. Instead, they added a feature to the App Compatibility Wizard that watches your app and, if it crashes after a DLL was unloaded and the moon is the right shade of Rondele, it adds a registry key marking this library as “never to be unloaded, even if this app says so”.

From that point on, the app doesn’t crash because the old semantics of FreeLibrary (“ha ha ha, you don’t mean that do you”) are restored in that one case.

The above is entirely made up – it’s my mental model for what might have happened, unless Raymond Chen someday gives us some back story.

Still, you can see what has gone wrong here – Windows decided that for compatibility reasons, plugins should not actually be unloaded, and since all of your DLLs are named win.xpl, this one plugin crash has caused plugins to never be unloaded. Thus the plugin unload/reload never releases the DLL and you can’t swap in new code.

Nuke the registry key and you’re back in business, at least until you crash again.


Posted in Development, Plugins by | 9 Comments

11.05 Release Candidate 2 and Friends

11.05r2 is now available – if you have 11.05r1, you’ll be notified to auto-update. We fixed the broken SIDs/STARs at KMCO, removed a few custom Aerosoft lego brick airports to reveal the gateway one, and we have some updates to KLAS from Julian.

This should come out on Steam in a day or two if no one finds something on fire and hopefully be final this week.

We’re working full time to get 11.10 ready for beta, hopefully very shortly after 11.05r2 is final.

Update: Steam users can get 11.05r2 as well by opting into betas.

Posted in Development, News by | 29 Comments

Talking to Plugins

We’re continuing to integrate X-Plane 11.10 (with mixed success!); we’ll get more info on 11.10 posted once we’re in beta.  11.05r2 will come out as soon as I get my hard drive fully restored – from the looks of the comments this should be Real Soon Now™.

This post is for plugin developers – if you don’t write plugins, I suggest cat pictures instead.

For as long as there has been OBJ animation, X-Plane has called the XLMGetDataXXX APIs from inside the OBJ engine as drawing is taking place. These calls eventually show up in your plugin in your dataref read callback. You might even see X-Plane code on the stack if you put a break-point in your read accessors.

This design has two major draw-backs:

  1. It’s bad for multi-core. Since the plugin API is single-threaded, operations requiring us to know the animation state of an object (drawing, collision testing, etc.) require us to be on the main thread. So this doesn’t scale well.
  2. It’s inefficient. We might have to draw your aircraft several times – one or more times for reflections, one or more time for cascading shadow generation, and once to draw (or more for multi-monitor). The work to fetch those datarefs is done multiple times, even though we don’t want different answers between drawing passes.

(In fact, it’s worse than that – if you have the same dataref used in multiple animations, we just request the dataref over and over…not real clever.)

X-Plane 11.10 changes this for the first time: we are starting to collect the entire set of datarefs we need to draw a model in a single burst. We can then save these dataref results and reuse them.

This is just the beginning of a series of changes to make the rendering engine multicore-friendly. Hopefully it won’t affect any add-ons* – this should have no effect unless you are doing highly illegal things with the SDK.

I am hoping we’ll see some performance benefit by not spending as much time in plugin code, but I don’t have numbers yet.

* Plugins that read the object-draw-location datarefs to do multiplex their datarefs on multiple models should still work; we set those object-location datarefs before we collect all of the datarefs for your model.

Posted in Development by | 19 Comments

X-Plane 11.05, 11.10, and My Mostly Dead Hard Drive

TL;DR version: my iMac’s fusion drive “lost its marbles” right before I went on vacation. This has delayed cutting an 11.05 release candidate 2 with a few scenery fixes, but we should get to it next week. In parallel, we’re working furiously to get all of the code locked down for 11.10.

Everything else that follows is really, really, really, really boring. I’m writing it only because some of my co-workers watched this slow motion car crash and tightened up their backup game a bit. If my drive fail can shake you out of complacency, read on.

Basically: my iMac is my main development machine, and the data is backed up and/or duplicated in a bunch of different places: a USB time machine archive, a Backblaze cloud backup (both are “full machine”), DropBox for virtually all of my documents, and my work for Laminar is kept on Laminar’s source control servers. Data loss was never a huge risk here.

Time loss, however, is a real risk! My goal was to lose as little work time to fixing my machines as possible. So my plan was: restore from time machine disk backup, request a cloud backup restore via hard drive, return the hard drive. The total cost would be a few hours of disk copying and less than an hour of my time. My development machine would be usable for new work while waiting for the cloud backup to arrive.

This has not gone as well as I had hoped! You can learn from my fail here — a few notes.

  1. Your backup might as well not be a backup if you have not checked that the backup contains the data you think it contains. It turns out that both the cloud backup and time machine backup were missing files!  I’m very lucky that they weren’t missing the same files.
  2. Time machine sometimes decides not to back stuff up. OS X has a hidden per-file/directory attribute that can exclude a file from backup without showing it in the Time Machine UI!  Once you check your time machine backup and find a folder is missing, from terminal you can do tmutil isexcluded <file path> to see if the file has been explicitly excluded.  If it is, tmutil removeexclusion <file path> fixes this.
  3. Backblaze ships with a bunch of file exclusions too – mostly designed to not archive stuff that isn’t your data. But beware – stuff you care about might not be on the list. (For example, virtual disks in a virtual machine are excluded by default.)  I had to add back .iso files to the backup list. Backblaze backups are also not bootable. This is something I can live with, but always read the fine print about what’s in the backup.
  4. The Backblaze data restore has been very slow – over ten days for less than half a terabyte and it’s still “in progress”.* While they haven’t exceeded the maximum restore time they advertise, it’s slow enough that the delay matters.
  5. One other note on Backblaze: I saw major performance problems on my iMac while Backblaze was running, even when a backup was not running (since they were scheduled for overnight). I do not think this is necessarily Backblaze’s fault – it may be a problem with CoreStorage (which “runs” the fusion drive) or even a fault with my drives. From what I can tell, cloud backup exacerbated it by putting a lot more file traffic on my system.
  6. A possible danger if (like me) you keep documents on DropBox to have them everywhere: when I restored my iMac from Time Machine, I was exposing DropBox to my data from a week ago. I didn’t wait to see if DropBox would figure out what happened; I unlinked my iMac while it was offline after the restore, then re-established DropBox and let it download my data. Better safe than sorry.
  7. I have been backing up to portable 2.5″ USB drives because they’re cheap and really convenient, but they have a down-side: the mechanisms can easily fail and take your whole backup down. I have five of these drives and one has failed in a three year period.
  8. I’m really unhappy with CoreStorage, to the point where I would not recommend a fusion drive anymore. CoreStorage is an Apple virtual-volume technology (similar to soft-RAID) that makes one small SSD and one large HDD look like a single unified volume, with some of the data “cached” on the SSD for performance. CoreStorage is a lot newer than HFS, so when things go wrong, most disk utilities you would go to just don’t work.

I actually ended up in a state where (after wasting almost an entire day) I could see my data, but only in single-user mode with a read-only file system. I might have been able to directly copy the data, but I picked to format the drive and restore from the backup to save more of my time and get back to coding X-Plane.  My suggestion for developers getting iMacs: get an internal SSD (whatever storage size you can afford) and supplement with a fast external hard drive over Thunderbolt.

Going forward, I am replacing the portable backup drives with a Synology NAS RAID device – this gets me high performance, high capacity backup (about 10 TB) with redundant drives. I picked HGST drives because they’ve had a good track record for reliability. With a large network attached storage server, I can have all of my machines backing up in the house all of the time, and have that be the primary way of getting my data back. I’m keeping cloud backup as a last-resort-the-house-burned-down kind of thing.

If my cloud backup hasn’t shipped Monday, I will rebuild the setup I use to cut builds by hand (it’ll take a few hours but it’s doable) and we’ll cut 11.05r2 that way. If the drive comes, I can get the last of my data back and we’ll get to 11.05r2 the easy way. Either way, we’ll get things moving again.


* I opted for a hard drive restore, which should have one day of shipping time, instead of a download; a smaller restore based on download made clear that the transfer speeds would be slower than FedEx for that quantity of data.

Posted in Development, Really Really Really Really Boring Stuff by | 31 Comments

XPlane2Blender v3.4.0-beta.3 is out!

If you have been doing work with manipulators during beta.1, please download this new one and review the notes! Download the latest here:


  • #ATTR_layer_group_draped causing KeyErrors
  • Reverts bad change to manipulators properties*


“.beta.3” will be printed on all OBJs. This is not permanent, expect something better in the future

What happened to the manipulators?

A poor decision to change the Manipulator Type (Drag XY, Push, Command Knob, Toggle, Delta, etc) means that if you changed the type of manipulator between beta.1 (or 7fe534ad1f906b7853827 if you constantly check out the latest cutting edge commits [which I do not recommend for this exact reason]), this beta will make those changes irrelevant.

Example, suppose on 8/1/2017 you create a switch and set the manipulator type to Toggle, then with beta.1 you change the type to Push. Beta.3 will show the type as Toggle. All you need to do is go back to the switch and change the type back to Push. The rest of the values you set will still be there. If you created manipulators during the beta, they will be set back to the default “Drag XY” type and will need to be fixed.

This is an unfortunate lesson to be learned, and if you are facing a lot of tediousness (30 manipulators to hunt down and change) or potential errors (you can’t remember how many or which ones you changed) please contact me!

I will personally help you recover the changes you made during beta.1 – present.


Posted in Aircraft & Modeling, Development, Scenery, Tools by | 5 Comments

XPlane2Blender v3.4.0-beta1 is out!

XPlane2Blender v3.4.0-beta1 is out!

The next version of XPlane2Blender is right around the corner, come test it! Highlights of this release are Optimized Animations, Increased Usability, and X-Plane 11 OBJ8 features (mainly Blend Glass mode and Normal Metalness). Read more about what has been changed on the release page and download it!

(Link to beta removed until major breaking bug has been fixed. Make backups of files before using any beta product.)

As with any beta, make backups before using a partially tested product. We don’t predict there should be anything breaking in it, but its never a bad idea to be safe.

Bugs and feed back on Github is preferred over this comment section, but most of all I want to hear your feedback. To stay focused, only comments related to XPlane2Blender, the beta, and Blender will be responded to for this section. The status of other 3D Modeling Plugins/VR/Weather Systems/etc is off topic.

Posted in Aircraft & Modeling, Development, Modeling, Plugins by | 9 Comments

Request for XPlane2Blender Documentation Improvements

Please tell me what confuses you about XPlane2Blender on this bug, or here!

We are going to be releasing the XPlane2Blender 3.4 beta soon, and with it, a refresh of the UI and documentation. Thanks to a great e-mail about a lack of documentation, it was put as an important part of 3.4 release roadmap. It goes to show… we can’t fix it if we don’t know what’s wrong, even if its not a code problem. And we do want to fix it, I swear!

In addition, I want to remind everyone a core part of the Laminar Research philosophy, identity, and business plan is a thriving modding and third-party plugin ecosystem. Aside from build scripts and the like, Laminar Research employees use the same scenery development tools that are available to all. This is was a deliberate choice that elevates everyone to the same level – except when there is a gap of knowledge. This is never intentional, and never benefits anyone in the long run, especially third-party-devs. If your work is suffering because we forgot that not everyone knows what every little checkbox means, tell us! We’ll put it in the bug queue like everything else, and try to get back to you, personally, quickly.

Posted in Aircraft, Aircraft & Modeling, Cockpits, Documentation, Modeling, Panels by | 29 Comments

X-Plane 11.05 (Release Candidate) – Airports!

We just posted X-Plane 11.05 today – to try it, click “get betas” and run the updater. Steam users: we’ll try to get a Steam version up in a few days if no massive bugs are found.

This update is really a release of airports from the X-Plane Scenery Gateway – see the release notes here for a complete list of airports included.

This release also includes our first land-marks: custom buildings from the strip near Julian’s KLAS, which is also included.


Posted in Development, News by | 64 Comments

Blender Exporter Testers

Ted and I have been working on a new version of XPlane2Blender for Blender 2.5. The new version mostly focuses on bug fixes and optimizations to get perfect WYSIWYG output from Blender to X-Plane with optimal OBJ code.

If you use the version 3.3.x of this exporter and would like to try test builds, please email me. We have a suite of test cases that we run the exporter through to confirm that it is operating properly, but it’s also useful to run it on real-world examples to see if there are cases we missed.


Posted in Development, Tools by | 12 Comments