X-Plane 11’s native VR support uses SteamVR, so let me clear this up now:
You will be able to use VR directly in X-Plane 11 with any distribution of our sim:
An X-Plane 11 digital download from Laminar Research (or any other reseller) if you have a 24-digit product key.
An X-Plane 11 DVD set from Laminar Research (or any other reseller) if you have DVDs.
X-Plane 11 on Steam if you bought X-Plane on Steam.
VR will work for X-Plane 11 no matter how you bought it. You do not have to have bought X-Plane from Steam to use VR.
(This post does not contain any guidance on supported hardware – I’d like to wait until we get further into beta and get some feedback on how system requirements affect actual users. This is just a reassurance that you didn’t buy X-Plane “the wrong way” for VR.)
What Is SteamVR
SteamVR is a free download from Steam’s app store that X-Plane (and many other games) use to talk to your VR hardware. We use SteamVR for both the HTC Vive and the Oculus Rift – X-Plane’s native VR support requires that you have both the Oculus drivers and SteamVR.
X-Plane 11.11 is now final – you’ll be notified to auto-update. 11.11 is a small bug fix release that fixes a few key issues that we didn’t find out about in time to get into 11.10. Here’s the release notes.
Our VR private beta program is underway – we’ve been cutting VR private betas in parallel to 11.11 testing; I’ll post more on VR over the next few days.
X-Plane 11.11 is available for testing – to get it, run the X-Plane 11 installer, pick “Update X-Plane” and make sure “Get Betas” is checked. Two big fixes:
This build should fix crashes for AMD users.
This build restores functionality for FltPlan.go and a number of other iOS moving map apps that.
X-Plane 11.10 went final Thursday night – you’ll be notified to update. Jennifer has a good write-up of the high level features here, or you can read the release notes.
11.10 was a big patch for us – new airports, new autogen, new lego bricks, the G1000, joystick profiles, London landmarks, and significant engine enhancements to both the physics and rendering engines.
We may do an 11.11 patch next week – we have a few bug fixes that didn’t make the RC. Jennifer gets a lot of bug reports over the weekend, so we’ll evaluate Monday.
VR Is Coming!
The rendering engine work in 11.10 gets the sim “VR-ready”, and Chris has been working on the actual VR features of the app in parallel to the 11.10 release.
The next major patch of X-Plane will be 11.20; it will feature native VR support for the Oculus Rift and Vive on Windows, and the beta is coming very soon.
An author asked me how to make a sound cone in FMOD for X-Plane.
For example, our Cessna features recordings of the engines from four different mic positions (front, left, right, and back) – our engine sound event contains four sub-sound events, with sound cones modulating when the sound can be heard. Think of a 90 degree cone sticking out from the engine to the front, the right, etc. Only if the listener is in the sound cone can you hear it.
Here’s the trick: X-Plane provides two special parameters that give you the bearing of the listener relative to the event. From this you can create your attenuation shapes.
In X-Plane 11.10, annunciator sounds automatically play even if you are using FMOD. This is confusing, particularly compared to 11.05 – here’s what’s going on.
We have two categories of sounds that are not handled by FMOD as of 11.10:
Radio sounds (where you have no way in FMOD to create the exact sound that’s going to happen, because it’s based on the ATC system or speech synthesis).
Cockpit warning bells and other “event” sounds that are triggered directly from the flight model code.
We are planning to make this second set of sounds FMOD-accessible in the future, but to do so we need to create a system for “events” in X-Plane that is accessible to plugins and the authoring interfaces.
My current thinking is that an “event” system would let plugins subscribe to notifications of events, wire up sound events to sim events, and create new events via the plugin system. We may even be able to eventually play particle effects in response to events. The events would have path names (similar to commands and datarefs) for flexibility.
I had hoped to get to this in 11.10 but we just didn’t have time, so this will have to wait for a future patch. When we do have sound events we’ll have a way to indicate in an FMOD .snd file that (1) you want to wire up sound to particular sim events and (2) you don’t want the built-in sounds anymore.
Here’s the current set of sounds that are played even if FMOD is in use. If you don’t want them, include silent waves in your aircraft’s “sounds” folder.
I hate finding out about these kinds of bugs late in the beta. But this one was pretty big.
X-Plane uses a “metalness” material model. Metalness is a fairly standard material model that recycles the albedo of your material to implement both dialectrics (non-metals) and metals. It works like this:
Non-metal: diffuse light is tinted by the albedo texture. Specular light is not tinted.
Metal: there is never diffuse light. Specular light is tinted by the albedo texture.
In other words, since metals don’t have a diffuse component, we recycle the albedo to save texture space.
The bug in 11.05 is that for a pure metal, the albedo was tinting ambient light but not the sun itself. A third party developer sent me a test model that showed the problem – here’s the before and after.
11.05 – sun spot is white.
11.10 – sun spot is red.
That weird set of colors on the top of the helicopter body is due to the white sunlight being added to the red body. The red aircraft body is lit by ambient light reflected directly off of the environment. The runway stripes are not visible because the metal is about 30% rough, diffusing the reflection.
(One of the confusing things about PBR models if you are not used to them is that the environment itself can cast both diffuse light and specular reflections off of a material, and if the material is rough, it can be hard to tell them apart. Diffuse light is always widely diffused, no matter how glossy the surface.)
Alex and I took a look at some of our legacy aircraft and found that fixing the lighting didn’t make too much of a difference for metals that are not tinted.
MD-80 11.05
MD-80 11.10
737 Engine 11.05
737 Engine 11.10
737 11.05
737 11.10
Since our aircraft don’t have any “tinted” metal there isn’t much change. Note that in real life heavily tinted metals aren’t common. The cases you might have are:
Approximations of metals with complex spectrum-dependent fresnel like gold.
Composite paint, e.g. like for your car, with fleks of metal and translucent dielectric polymer mixed together – that’s the case where this really helps.
As I wrote this up I realized that the spot lights are still wrong in beta 8 – they’ll be fixed for RC1 unless people really need the old model, in which case we’ll have to put some versioning in. My guess though is that anyone doing composite paint realized it was impossible in 11.05 and hasn’t shipped anything like that yet.
Plastic on top, metal on bottom, 11.05
Plastic on top, metal on bottom, 11.10
Red material, varying metalness and glossiness, 11.05
Red material, varying metalness and glossiness, 11.10
In these comparisons we are under an airport light viewing various materials. In the multi-color case the bottom row of materials are various “metals” with light tinting to simulate copper, iron, gold, etc.
In the second set of cases (all red) we have a 2-d grid: metal on the bottom, dialectric on top and rough on the left and glossy on the irght. Note that the reflection of the overhead light is reddish for the metals and white for the plastics in 11.10 (correct) but all white in 11.05 (incorrect).
We’re mostly down to small bug fixes – no more big flight model changes.
The next build will probably be 11.10rc1.
We’ll get Steam updated in the next few days – Philipp’s been traveling a lot.
There are no remaining major enhancements that have to go into this beta. Here’s how some of the big technology changes played out:
The new manipulators are in – I’ll write up a separate post tomorrow on those. They went into beta 6 (hence all of the weirdo bugs) and are now fully working.
All of the new weapons code is in – dataref access to weapons is restored. Jörg has a few crash bugs to nail down with networking and weapons, but that’s it.
Audio events had to wait – I’ll write that up in a separate post. They’re something we wanted, but realistically we never had time for them in 11.10.
The last round of performance enhancements for graphics is going to wait for the next release patch.
The bad news is: AMD users aren’t running 11.10’s fastest path due to problems with our current code and drivers. The good news is: the next round of enhancements do work with AMD cards, so we can get back to treating them normally. That code is now looking reasonably stable, but it wasn’t stable early enough to make it into 11.10. I think it will be available in beta this year though.
Finally, there was an open question of how to use glScissors in a plugin with the new UI features (e.g. floating windows, multi-monitor, 150% UI, etc). As of beta 8 this is fully possible; I just need to get the sample code to Tyler to post.
Two flight model notes for aircraft authors – the executive summary of all of these is pretty much “it should just work and you don’t have to do anything.”
Steering Gear Rate Limiting
X-Plane 11.10 has an option to rate limit how fast gear that steer can turn. This is a good thing – in the real plane you just can’t turn that tiller very fast, but if you have a $20 Microsoft Sidewinder from 2002 with the throttle tab broken off (for example) you can twist it to full deflection almost instantly. When this happens, X-Plane turns the wheels instantly, and since they’re not at a 70 degree angle to your movement path, they skid like Ken Block landing a Baron. Once the wheel is in skid it has pretty much no ability to turn the plane and you just skid.
With rate limiting, the wheel will turn a little bit, and be able to put out side force, helping the plane begin to rotate. As this happens, you can turn more and gradually angularly accelerate the aircraft into a turn.
So … rate limiting is good – you should use it! But the compatibility code in beta 7 was pretty broken – it set the minimum rate to 1.0, which is way too slow for a bunch of aircraft.
Beta 8 fixes this – the minimum rate is 0 (meaning no limiting) and this is the default for 11.05 planes.
Here’s the warning: if you saved your aircraft in an earlier beta, you’ve baked in the long gear deflect time – you’ll have to go into Plane-Maker and turn the value back down again.
Just One Turbo-Prop Model
X-Plane 11.10 had two options for free turbine turbo-prop engine models: the “v10” and “v11” models; all 11.05 planes showed “v10” when loaded in Plane-Maker.
We’ve backed this out – there’s just one model, “turbo-prop (free)” in beta 8, and if you picked the v11 model, we’ll mark it back to v10 for you. (You shouldn’t be shipping aircraft saved in a beta anyway, but we check for this in the sim itself too.)
Here’s the back-story: X-Plane models the compressor turbine speed of a free prop turbine like the PT-6 as “N1” and the prop turbine speed as “N2”. Austin has come to regret this decision, as the prop turbine is a lot more like the turbine that drives a bypass fan in a high-bypass jet engine, and the compressor turbine is a lot like the turbine that drives the core in a high-bypass jet engine.
So Austin cut a new version of the engine model with N1 as the prop and N2 as the compressor, exactly backward from 11.05.
The thing is: while the new model matches Austin’s brain, it doesn’t match any aircraft ever made, and swapping N1 and N2 in an add-on is a pretty expensive update. Realistically we’re not going to ever deprecate the old model for the new one in any time frame if this much rework is needed.
So we’re keeping the new model ‘in the lab’ and not releasing it for now, as it doesn’t have significant changes in how it models the engine itself yet. This frees Austin up to improve it on his own schedule and frees us up from having to maintain another point of version compatibility. Since the new model doesn’t have any enhancements (other than renaming N1 to N2 and vice versa) you’re not losing out as an aircraft developer here.
Tyler heard your pain (as did the rest of us, as we received approximately 8,414,493 requests to kill the FPS nag) and we have changed the low frame-rate warning from the perpetual flashing “you’re too slow” shown on the left to the pop-up warning on the right. And if you like flying a slide show, you can click “don’t show this again” and … we won’t!
The new warning is a bit more conservative – you should only see it if you’ve got persistently low framerate – a transient dip due to texture paging should not make it pop up. If you see it appearing spuriously, please file a bug. In these pics I’ve set my poor 3-year-old iMac to maxed out AG, maxed out shadows and maxed out shaders all at once with the 747 to dip below 20 fps.
The rest of this post discusses the “why” behind this dialog box.
X-Plane Requires 20 fps (or: How Did We Get Here)
X-Plane has some fundamental rules about how it simulates flight – these are our design parameters.
X-Plane simulates one physics frame and renders one graphics frame in lock-step – physics and graphics do not run independently.
X-Plane’s physics model will not “step” the simulation forward more than 50 ms in each step, to avoid computational flutter and other flight dynamics problems.*
X-Plane allows you to set your rendering settings as high or low as you want, even if you don’t have hardware that can render a graphics frame at those settings in 50 ms.
If you consider all of these things, you can see the problem. You can crank up your settings on an old machine and the rendering engine needs more than 50 ms but the physics engine won’t simulate more than 50 ms in a single step.
X-plane does the only remaining option: if your computer cannot sustain 20 fps rendering, your flight will be simulated slower than real time. For example, at 10 fps, a flight from Boston to JFK will take 90 minutes, not 45.
It turns out that lots of X-Plane users don’t know about this behavior, and as a result, Austin receives a steady stream of emails complaining that the sim is unrealistic because en-route times are too long – virtually all of them are caused by low fps.
So for 11.10, Austin did what Austin does: he put a big loud message on screen to tell users that they were below real-time simulation.
We Should Probably Say Something
The result of this message was not users going “oh, I’ve learned something, I’ll turn down my rendering settings.” It was a huge number of bug reports that X-Plane 11.10 had catastrophically worse FPS than X-Plane 11.05. In many of these cases, users thought they were getting 20 fps because the flight model reads 20 fps in the time window data output (a very confusing display) and there is no bitch-o-gram.
I considered the option of just nuking the message a second time, but there may be problems with running at low fps that users don’t realize. For example, if you’re on VATSIM doing 170 knots on final like the controller asked at 10 fps, you’re doing…85 knots and your 737 is looking a lot like a C172.
So we went with Tyler’s popup + never-show-again design; it brings the issue of low fps to the surface, but lets users dismiss it forever if they can live with non-real-time simulation.
Why Don’t You Just Split the Physics and Graphics
When discussing this with users I did get asked a lot, “why don’t you run the physics and graphics independently so we can run in real-time at < 20 fps”. There are a few reasons why we did not (and are not) considering this approach.
Separating the execution of the physics and graphics code would require significant engineering work – right now they run in an alternating pair, and therefore they don’t need to be coordinated at all. Once they run independently, a bunch of new code is needed to mediate their interaction. That engineering time would take away from just making X-Plane faster.
The cost in CPU time of coordinating the independent FM and graphics would not be free, so this would make the actual frame-rate for the sim worse in pretty much all cases.
Our goal is to make X-Plane run at 60 fps, and we consider 20 fps (the minimum) to already be really quite awful. So we really want to focus on making X-Plane faster, not on making it work better at a frame-rate where the user experience is very sub-standard.
So we’re going to keep focusing on performance optimization that will benefit everyone and not take a side-tangent into making 15 fps flight run in real-time.
* If the time between frames is too large, self-damping forces on the aircraft and feedback-based control systems will not react properly because they will not respond quickly enough, due to there being no simulated frame shortly after a large force is introduced. The result can be incorrect handling at the outside of the flight envelope, for example.
X-Plane 11.10b4 is out. The release notes have complete bug fixes (we try to list everything; Jennifer works off the bug base and the GIT commit log), but two big fixes:
Austin fixed a crash for aircraft with zero stall speed. If your aircraft was crashing 100% of the time in b3, please re-test in b4 and file a new bug if you still see a crash.
Plugins using widgets were being subject to the new scaling/multi-monitor capabilities even if not re-compiled against the new SDK. We think this caused a ton of plugins to stop working.
Widget-based plugins now do not scale. The widget drawing code path, as it turns out, is totally not ready for UI scaling or multi-monitor.
If you found any problems using plugins (mouse clicks not working, double drawing, things disappearing) and you still see them in beta 4, please re-report a new bug based on whatever you now see!
Plugin authors: our intent is to not scale widget-based plugins – the widget drawing path is full of assumptions about the drawing environment, and the code is split between plugins, public libraries, and the DLLs in X-Plane itself.
Our long term intention is not to upgrade XPWidgets, but rather to offer some kind of modern replacement that leverages our UI, is easier to use, and is compatible with all of the modern facilities in X-Plane.
Unfortunately that doesn’t leave widget-based plugins with a lot of good options in the short term. As a plugin author you’ll need to look at the scope of your UI and decide whether you’d rather recode it in straight XPLMDisplay APIs or wait until an XPWidgets replacement is available.
