The X-Plane 10 Core Engine

Tyler Young

From Austin, lead developer and owner of X-Plane:

I have a write-up a mile long of all the features already done for X-Plane 10, but let’s save all those details for later.

Other than a gajillion various flight-model and scenery over-hauls and a near-complete internal re-write to make the code more object-oriented and thus easier to modify and debug, let’s look at the fundamental requirements I have laid out for my team for X-Plane 10, all of which are being developed now.

In a sentence, X-Plane 10 will have a plausible, scalable, dynamic world.

Here is what I mean:

Orthophotos are garbage. I see this all the time. I am zooming along in an airplane looking that rooftops of WalMarts painted flat onto the ground. And the rooftops are blurry. And pixelated. And with a magenta or purple tint. And with big blurry shears right through the middle of them when they fall between offset satellite passes. It looks just terrible. Then, to make the 2-dimensional, blurry, pixellated, mis-colored, distorted roof of a WalMart painted on the ground look even worse, if you throw in some REAL roads or auto-generated buildings, they invariably fall ACROSS the roof of the WalMart painted on the ground, compounding the wretched orthophoto with an Escher-like rendering-error. This looks terrible, and is not even plausible.

Enter the plausible world for X-Plane 10.

We will build every city in X-Plane UP FROM THE FIRST BLADES OF GRASS.

Here is how it works: We will start off with grass or field textures for THE ENTIRE WORLD, INCLUDING THE CITIES, and then build up from THAT. We will take each individual parking lot and place it on top of the grass. We will place each building on the parking lot, in 3-D. At no point will the PAINTING of the ROOF of a building appear on the ground. This will NEVER happen. EVERY building will be a real 3-D building, planted by an algorithm in a location that is at least physically possible. Do we know where every building on earth is? Of course not. But, we DO have incredibly detailed road databases, and we have the algorithms to place parking lots, sidewalks, buildings, etc. all alongside these countless roads. This means that our artificially-intelligent city-planning algorithm will build PLAUSIBLE cities. Cities where you would fly over them at 5 miles per hour, 10 feet above the ground, in a helicopter, and NEVER see anything that looks ‘impossible.’ Everything will be completely 3-D. Every city built from the first blade of grass. There will be no discoloration, blurriness, satellite mis-alignment or 2-D Escher-illusions–all of the cities will be completely plausible. If you turn down your rendering options to zero, then New York will be empty green fields. If you turn them up to max, then it will be a sea of 3-D roads and buildings at a level of detail that you could DRIVE in a driving sim, and Central Park will NOT be an overlay–it will simply be a part of the field that they have not put buildings on! This is the plausible world, and it is the first step towards a really detailed and convincing virtual reality.

As well, X-Plane 10 will be SCALABLE. While you will be able to taxi right down the roads, with plausible intersections at every crossing and only 3-D buildings off of either wing, you will be able to zoom out all the way to space and see the landmass from orbit. You will see the reflections and lighting of the land and sea from space, with smooth transitions all the way from space to sitting in someone’s front yard, never with any sudden switch-over to a different rendering technology. Everything is done with level of detail that delivers smooth transitions from street-view to orbit, all in 3-D. The WEATHER system will be detailed enough that you will see cloud whisps right around your plane as you fly through clouds, but will go HUNDREDS of miles in every direction WITHOUT any repetition. This will let you have fronts and thunderstorms, areas that are VFR and IFR, clear and cloudy, all at once, depending on your location. If you want to fly like you would in reality, you will work through/over/under/around those thunderstorms and fronts getting from one place to another, since the weather is NOT homogenous or repetitive. It scales from local detail around your plane clear out to region-wide fronts and storms visible from orbit. Totally scalable across a tremendous range.

As well, the X-Plane 10 engine is DYNAMIC. I have now, for X-Plane 10, made it so that EACH FLIGHT MODEL RUNS ON IT’S OWN CPU. Here is what that means: If you have 20 processors, then you can run TWENTY AI PLANES WITH BASICALLY ZERO FRAME-RATE HIT. Crank the number of planes up to 20 in X-Plane 9 and watch what happens to the frame-rate. Try it now: Set the number of planes to 1 and look at the frame-rate. Then set it to 20 and look again. See the hit? That is because all of those flight models are running on ONE CPU, one after the other, in order. With X-Plane 10, each flight model can run on it’s own CPU, all at the same time–if you have 20 CPUs, running 20 planes is no slower than running 1. Now, most of you don’t have 20 CPUs, but if you have a quad-chip dual-core (per chip) Mac like I do, then that is EIGHT cores–and they can handle 20 flight models while hardly breaking a sweat. The frame-rate impact of 20 planes is small: We have eight cores splitting the work! As well, we have optimized the RAM-use of each airplane to be considerably lower. This means that there is less RAM impact to having 20 planes flying at once, making it much more feasible to have 20 planes at one time. So, X-Plane 10 will use less RAM, and give more frame-rate, than version 9 when loaded up with planes (all other settings being equal, of course). So why do I care about all these OTHER planes so much? Well, we have hired a full-time programmer JUST for the new ATC code for X-Plane 10. This new ATC will control ALL the planes in the sky, including yours, to deliver incredible ATC realism. Using pre-recorded WAV files, you will HEAR the controller giving instructions to the OTHER planes, and see them following those instructions on your TCAS and out the window. The other planes will all take-off, land, taxi, stop on the ramp, miss approaches and do touch-n-goes, all while taking commands from ATC, all of which are audible on your radio.

Of course, all of the other planes will use the same accuracy flight model as your plane, so you will see them move perfectly realistically across all phases of flight, from flying right down to taxiing. Put in a strong wind or turbulence and see how they handle it. It might not be pretty, but it WILL be realistic. Set enough wind and an icy runway, and they will all blow right across the ramp. Watch out.

So, THIS is the plausible, scalable, dynamic world that we are building for X-Plane 10, all of which sits on top of an object-oriented, RAM-optimized, CPU-optimized, multi-core-capable code-base. You will SEE these results as X-Plane 10 reveals incredible detail, motion, and accuracy at all scaleswhile the activity bars on ALL your CPU’s run up into action.

NOW, if you only have ONE CPU and a LITTLE BIT of RAM, you will still be able to run version 10 just fine… in fact you may see it even run FASTER and with LESS RAM than Version 9! BUT, you will have only ONE airplane, and the cities will be simply grass fields, and the air traffic controller will have very few people to talk to. BUT, if you get the 4 gig of RAM to load up the rendering options, the 8 CPU cores to run 20 AI planes with full flight-model at once with minimal frame-rate hit, THEN you will start to see the whole world enrich and come alive. But there is no way that is happening with 2 gig of ram and one CPU. This type of world is all about parallel-processing: A lot of stuff happening at once. No surprise it will eat up all the CPU’s and RAM (up to 4 Gig) that you can give it.

Anyhoo, as X-Plane gets ready to ship around the end of this year, you will want 4 gig of RAM and 4 or 8 CPU’s if you want to crank everything up to see all of this, and you can expect more and more high-quality planes to start moving over from MSFS o X-Plane.

Never miss an update.

More X-Plane news comes every month. Sign up below to never miss an announcement.