On my way back from South Carolina a few weeks ago I had some time in the airport to fix the WorldEditor 1.1 export bugs. All of the reports pointed to a single cluster of bugs that are hopefully now fixed in beta 2, and today I finally had time to get the betas posted.
I also cut a new build of MeshTool (2.0RC2) while I was doing builds; this fixes a bug when using orthophotos with varying physics.
So first: you can get the new WED 1.1 beta 2 and MeshTool 2.0 RC 2 on the tools page on the wiki.
The wiki? Yeah. Tyler has been helping me migrate the scenery tools to here. At this point I believe that all of the content on scenery.x-plane.com is now duplicated on the wiki (which also has additional articles).
WED Bugs
If you should find additional WED bugs, after you get over your initial surprise, please file bugs in the scenery tools bugbase. Please do not email me bug reports. WED has to take second priority to version 10 work, so I don’t have time to process bug reports now, and I will lose them. The bug base keeps your bug safe, keeps a record of what happened to it, and can take attachments.
Please do provide the minimal materials to reproduce the bug; simple packages with an earth.wed file are great. Thanks to all of the WED users who filed bugs with repro cases – this made it very easy to retest the export code.
My Polygon is Poly-Gone
It is illegal to have DSF polygons (or airport polygons) cross themselves; finally with beta 2, WED actually makes this case fairly easy to detect.
- If a polygon cannot be exported (because it is self-intersecting), an error message will indicate that some polygons were skipped, and those polygons are selected.
- If you pick “Error-Check Polygons” from the Edit menu, then for every polygon that has a self-intersection, an OBJ is added at the precise point of the self-intersection. Simply select and zoom in on those OBJs – they act as marker pins to show the problem. Delete the OBJs once you have untangled your polygon.
(I did experiment with error checking on the fly, e.g. simply showing red dots in the intersection points as you drag and resize the polygon, but the math is too slow. I am using CGAL to check bezier polygon intersections, and their algorithm is absolutely rock solid, but it can take up to a quarter of a second to recheck the polygon, which is too slow for interactive editing.)
UPDATE: beta 2 hangs when processing beziers. What is very odd is that this happens on the clean release code but not the working copy of WED I fixed the bugs in. Hence, when I checked all of the bug reports, they all passed. I have reopened all bezier-related bugs. I have not yet located the build environment differences causing the problem.
UPDATE 2: the hang on bezier processing was due to a bad compile configuration for a library WED uses, and was Mac specific. Having fixed this, I have recompiled and reposted WED beta 2 for Mac. If you already grabbed WED, re-download it, and make sure you get the version dated September 24th. You can tell you have the right one because the “compiled on” date in the about box will say “Sep 24 2010 19:34:09”.
For quite a while now, I have been advocating in favor of DDS compression. I am pretty damned obstinate, but eventually if enough people yell at me, I get a clue. I have come to appreciate that there are some cases where DDS compression is not a net win; this blog post explains when it happens and what we might do in X-Plane 10 to work around this.
DDS – The Good, The Bad, the Ugly
DDS is a file format that contains image data pre-mipmapped (that is, the smaller versions of the image that the video driver needs are included) in a format that may or may not be compressed. DDS is virtually always used with a compressed image format (like DXT1 or DXT5). This has three positive effects for X-Plane:
- Because the image is already compressed, we save CPU time when loading the texture that would be spent compressing while X-Plane is running.
- Because small versions of the image (the “mipmap pyramid”) is already in the file, we save time down-sizing the image with the CPU, another win for load time.
- Because the image is compressed ahead of time, it can be compressed with a slow high quality compressor rather than a fast low quality compressor, so relative to other compressed images we get an image quality improvement.
The bad is that the DDS file does not contain the original uncompressed file. If the user unchecks “compress textures to save VRAM”, DDS files remain compressed. If the image file contains details that don’t compress well, they’re going to get splatted and stay splatted.
What If VRAM Grew On Trees?
My original heavy arguments for DDS were based on the idea that VRAM is a limited commodity; if we don’t compress textures, the user runs out of VRAM faster and has to go down a level of resolution…and once that happens, everything starts to look ugly.
But what if the user has 1 GB of VRAM? At this point, we’ve limited the maximum quality the user can see because we don’t have the original uncompressed image anymore, only the DDS/DXT version. This can be frustrating to authors who spent a lot of time on their textures.
If you ship PNGs with your airplane or scenery, turning off texture compression will reveal this beautiful, uncompressed image, but now when texture compression is on, the compression will be done by the video driver, and that will look extra ugly.
The Best Of Both Worlds
This is my thinking for version 10. (These are just musings, we haven’t coded this yet.) Currently DDS are preferred to PNG files. We could relax the load rules in version 10 to prefer PNG over DDS when texture compression is off and DDS over PNG when it is on. This would allow authors to ship both PNGs and DDS files and have the right one be picked for the scenario: the pre-compressed one when texture compression is on and the uncompressed one when compression is off.
Yesterday I got a bit cheeky regarding feature requests for X-Plane 10. Here are a few slightly more serious thoughts regarding the feature request process.
The major features that we are putting into X-Plane 10 were decided, for the most part, a long time ago. Those who we met in France two years ago won’t be surprised by the major items on the list: weather, ATC, airports, and new scenery, new shaders. For that kind of major feature work, we have to start an initiative very early on. Heck – global sun shadows (which I believe we will ship in v10, God willing) were in the works before version 9.0 shipped – it took that long to get an implementation that was useful! (In fact, the v9.0 version was not released because the quality was bad, which is why I am always nervous about announcing features in advance; it ain’t over until it’s over.)
So while it’s exciting to see so many people discussing X-Plane 10, realistically if a feature is a “big” feature and we haven’t started it now, it’s not going into 10.0. That train left the station over a year ago.
There have also been two complicating factors that have cropped up during the X-Plane 9 run:
- Microsoft closed ACES, which definitely changes what we want our next major release to look like.
- The iPhone came along – until the first iPhone release, we had no idea that it would be such a big product.
While we have to plan our big features in advance, the market we are going to ship into changes during development.
So bear with us – a lot of what I see are good ideas that we will get to soon, even if they don’t go in the initial roll-out.
Quick airplane links:
- Carenado’s Mooney M20 J is out, available on the X-Plane.org store.
- Javier’s T34c Mentor is out, available at X-Aviation.com.
Pictures available in both links.
X-Aviation has released the Duchess, pics here.
Carenado is coming to X-Plane, initial pics here.
I realized I have slightly better test shots of global illumination than the ones that got out a week ago. These are from only a day or two after the last shots.
This is the Cirrus again, with landing lights and strobes; you can see that all of the airplane’s lights contribute dynamically to the lighting on the fuselage and doors as they move. (Yes, that is heat blur on the engine; the heat blur still needs a lot of tuning.)
This shows airplane-mounted lights interacting with custom scenery. In this case the standard Cirrus (with global lights attached) casts both strobe and multiple landing light spill on LOWI. One of the powerful results of global illumination is that we get correct lighting interaction between diverse content, including third party content.
Finally, this shows an airport beacon lighting a plane and vice versa. The global lights on the airport beacon are inside an animation group, making them “sweep” the airplane, which can in turn animate the airport beacon. With global illumination, there are no rules about who lights who.
Thanks to my foolish use of unprotected directories, we have basically announced that X-Plane 10 will feature global illumination. Here is some basic information on global illumination.
What Is Global Illumination?
Global illumination is the ability of any part of an airplane or scenery system to cast light on any other part of the scenery system or airplane. In X-Plane 9, the only lights in the sim that ever actually cast cast light anywhere else are:
- The sun.
- The airplane’s landing light. (Even if your plane has many landing light billboards, there is only one spill effect.)
- Three 3-d lights in the 3-d cockpit.
This list was kept short due to the high cost per pixel of each light on all rendering.
When X-Plane 10’s global illumination is enabled, a “spill” light attached to any OBJ can shine light on anything near it. Since any OBJ can have a spill light, this means we can have light sources on airplanes, scenery, cars, whatever you want. The spill effects any 3-d scenery nearby, even from another scenery pack.
This kind of still effect can be simulated in X-Plane 9 by careful use of LIT textures. However, real global illumination works between art assets created by separate authors. You can drive your custom airplane up to a custom airport and the landing and logo lights on the airplane will cast light on the terminal; the apron lights from the terminal will cast light on the airplane.
Furthermore, global illumination is fully dynamic – as objects animate or move, the lighting effects are correctly applied in 3-d. This makes effects possible that cannot easily be created using LIT textures.
Requirements for Global Illumination
Like most new rendering tricks in version 10, global illumination will be a rendering option that can be optionally enabled by users who have a video card meeting hardware requirements. In the case of global illumination, that requirement is a DirectX-10 generation video card, e.g. any Radeon HD , nVidia GeForce 8000 or 9000 series, and “100” series (100,200,300,400 series).
For authors: global illumination is applied using named and parametrized lights on your OBJ. Anywhere you can attach a light billboard, you can attach a spill effect as well, with some tuning constants for how wide you want the light, etc.
It will be possible to create two versions of your LIT textures, one to be used when global illumination is enabled, and one when it is disabled. Thus if you are baking lighting into your textures with a 3-d modeling program, you can simply re-bake the lit texture with some lights disabled and add 3-d lights to your model. The result is an airplane with real 3-d lighting where possible, and a close approximation via baking otherwise.
Global illumination can be added to a model incrementally; existing art content will work normally with global illumination enabled or disabled, so authors can choose to add a few light spill effects or add a large number, as time permits.
The Cost of Global Illumination
Global illumination isn’t going to be free. The main cost is an increase in VRAM use and fill-rate. The cost of global illumination is mostly a one-time cost to put X-Plane into a new rendering mode. (Graphics nerds: global illumination is implemented via deferred rendering.) The incremental cost of lights isn’t that high, although a scene with a lot of lights will have impact.
My expectation is that users with new, highly capable high-end graphics cards will be able to run global illumination easily, but will lose some of the other benefits of fill rate. (For example, running at 2560 x 1024 + 4x FSAA is a lot more painful with global illumination than without.)
Global illumination also introduces two artifacts, both of which I am trying to minimize as best as I can. These artifacts are a function of deferred rendering – all games that use deferred rendering have to address these problems:
- The lighting calculations are shared between multiple translucent surfaces, which can create some strange effects. For example, if a translucent window is in shadow, the scenery behind the window will appear to be in shadow too.
- Traditional full-screen anti-aliasing is not available with deferred rendering. We should be able to offer a simulation of 4x FSAA as well as some kind of cheaper FSAA-approximation, but the cost will be quite a bit higher in fill rate than the 16x-style CSAA available now.
(Hardware-based FSAA can make a number of optimizations like CSAA to optimize throughput; this is how such high multiples as 16x are possible. Since our implementation is similar to “super sampling” and costs a real 4x in performance, 4x will be the highest setting.)
Why Global Illumination
Of the new X-Plane 10 rendering engine features (and there are a fair number of them), global illumination is certainly the one that has the most impact on the structure of the rendering engine. With global illumination, X-Plane effectively has two separate modes (“forward” rendering, which is the only mode X-Plane 9 has, and “deferred” rendering, which produces global illumination).
One of the reasons to get global illumination done earlier than other features was that implementing global illumination required rewriting or modifying nearly every piece of low level rendering code. Now that the work is in place, we can safely add new features and test them in both modes.
Global illumination also meets two requirements:
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Sergio has long observed the central importance of lighting and shadows in the look of X-Plane; at some point more polygons and better textures still look synthetic without a realistic illumination model. Global illumination makes a more realistic lighting model possible at night. Airports represent an environment that can hopefully take advantage of such capabilities in a big way.
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As hardware becomes more powerful, authors have to do more work to create content that takes full advantage of the rendering engine. We are reaching a point where artist’s time is going to be a limiting factor as well as hardware and engine capabilities. Global illumination thus kills two birds with one stone: it makes the rendering engine’s output look better, but it also makes the whole scene look better with less work by the artist.
(For example, when baking lighting into a model, the author must plan the model’s texture UV map to guarantee unique texture space for all spill effects. When lighting effects are dynamic, the author can simply texture so the model looks good without worrying about baking requirements.)
There have been a few posts about X-Plane 10 in a few random places; here is a summary of all of the version 10 material that’s been previewed so far, and some notes on what is actually being shown.
First we had Paul’s Oshkosh 2010 video:
http://www.youtube.com/watch?v=yCoDPNvOMP0?fs=1
I think this has been made clear already, but:
- The base simulator shown here is not X-Plane 10, it is X-Plane 9.
- Many of the airplanes shown here will be released for X-Plane 10.
- This is not showing the new X-Plane weather system or global lighting.
- Some of the content shown here are third party add-ons, available today for X-Plane 9.
The main purpose of this video was to show X-Plane off at Oshkosh; at the time we didn’t have X-Plane 10 in a state where we could do an exclusive version 10 preview.
Then I accidentally leaked two test videos of global illumination. This was strictly accidental: I was looking for a cheap way to post a large video for Austin and Propsman late at night and didn’t think anyone would sift through 191 zip files to find two obscurely named videos. I was wrong, and someone found them on the org. I appreciate that participants in the ensuing discussion withheld judgment; these were early test videos and don’t represent the final feature in any useful way. They do, however show off some of what global lighting will mean.
- This is the Cirrus Jet with landing lights implemented via global illumination. We get two distinct landing lights that cast specular hilights on the fuselage. As the door animates, it opens “into the light”.
- This is the Avanti Piaggio with strobes and beacons implemented via global illumination. The strobes cast light both on the fuselage and on the runway below the plane.
This second movie is typical of the kinds of tests I do: the beacon lighting is just awful – a gross huge red light splatted on the plane for test purposes. When I get the rendering engine code working I usually hand the feature off to Propsman or Sergio to tune the textures and art constants. In this case, the videos are pre-tuning.
Austin has posted three screen-shots of X-Plane 10-related content:
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This is Javier’s new shuttle, which I believe will ship in version 10. I believe this shot may have been taken in X-Plane 9. So this is not the new weather system.
Some of these screenshots and Paul’s video were shot in X-Plane 9. By the time the new airplanes are finished, they will not be usable in version 9 – they will be version 10 only.
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Propsman has done work on the lighting system. It can be subtle to see what’s going on here because the old runway lights looked pretty good too, but most of these billboard lights are actually rebuilt.
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This night shot shows global illumination in the scenery system. The glow on the highway pavement is not rendered; it comes from the 3-d lamps along the side of the road. Similarly, the car headlights spill light on the pavement and each other as they drive. (Note how the highway lines are visible in the headlight spill even when there is no streetlight.)
One difficult problem with rendering a lit highway at night is that the lighting from street lamps on a highway tend to spill light on the surrounding terrain, an effect that is impossible to create with a LIT texture. If you look at the right side of the main highway at the bottom of the picture, you’ll see that the street light is casting light on the grass to the right of the highway too.
I think that that’s all we have posted. At least, it’s all I am aware of. I will go into some of the details of global illumination in another post.
I’ve been working on road processing today; one of the tricky problems with OSM data is that, because an OSM map is often a collection of vectors from separate authors, the results can be a huge number of very small segments, as nearby road features from different data sources cross each other. (Basically you get “thrash” between the two vectors from different sources and our tools solve this by adding a huge number of extra vertices.)
I am trying to run this data through an algorithm called Iterative Snap Rounding (ISR) to reduce this mess of vertices, and for the purpose of this blog article there’s one thing you need to know about ISR: it is really, really slow. So for the next few minutes, I figured I’d start poking at some of the issues that came up at the X-Plane Congress in France this summer.
One question that came up was whether/when X-Plane will go 64 bit. Here’s my current thinking:
We can’t drop 32-bit X-Plane. Too many users have a 32 bit operating system, or a 32-bit CPU. One thing I have been resisting for X-Plane 10 is a ratcheting up of the system requirements to only top-end game machines. While 64 bit is becoming more prevalent and has the potential to be a big win for users who load the sim up with third party add-ons and have a high-end graphics card, plenty of people buy a computer first and then discover X-Plane. Those users will often have a system that is low end (by X-Plane standards).
If we start cranking the system requirements (you have to have 64-bit, you have to have a DX10 class graphics card, you have to have 2 GB of RAM) then more users who might discover X-Plane won’t even be able to run the demo, and that will be bad for X-Plane’s growth.
So the question is not “when will we switch from 32-to-64 bit” – it is “when will we support both 32 and 64 bit.”
I think we will get there during the version 10 run, but I don’t think it’s that likely that we’ll ship 64 bit right out of the box. 64 bit is more of a performance enhancement* than a new feature. The features we have strong motivation to get into 10.0 are:
- Anything that raises the system requirements, because we don’t want to raise system requirements after we ship in a free update.
- Anything that enhances the authoring SDK, where it might be useful for authors to know that every version of X-Plane 10 has a feature.
- Of course, we want to ship any feature that looks really good and gets people excited.
- Foundation features that support other featuers have to go in first. So some enhancements that will ship in 10.0 are there because without them other tech couldn’t be rolled out.
64 bit is important, but it is a feature that only helps some of the user base, and helps by making the sim more expandable; the sim is still usable without it. So we’ll get there, but new features are a zero sum game so I think 64 bit is more likely to be a free patch than in-the-box.
(At this point I expect the various 64-bit OS users who have been asking for a 64-bit app for years to flame the heck out of me and point out that I am a cranky old bastard who doesn’t realize that 64 bit is now everywhere and totally pervasive and that this is therefore the most important thing we could possibly do. Before you dig in, hang on one second, let me put on my asbestos flame-retardant jacket. Okay…fire away. 🙂
Oops…ISR just finished…with a seg fault. Gotta go!
* As a performance enhancement, 64 bit is a weird one; because a 64-bit app uses more memory for pointer-based structures, the same data structures become larger, thrashing on-chip caches more. The real benefit to 64 bits is to allow X-Plane to use more than 3 GB of physical RAM.
Austin attended the French X-Plane Congress last weekend; in response to some questions I have received, I want to clarify what is planned for DSF and X-Plane 10.
X-Plane 10 will extend DSF scenery capabilities by providing a number of new art asset types, as well as extensions to existing art asset file formats. We will not be changing the DSF file format or breaking compatibility with existing DSF scenery. If your DSF scenery works with version 9, I expect that it will work with version 10 as is.
(In fact, it looks like we do not even need to add new DSF extensions; DSF was designed to be a generic container for geometry data and properties, so we can usually extend X-Plane’s scenery system by simply defining new art asset classes and properties.)
An example will illustrate what I mean by extending the art assets, not DSF.
In X-Plane 9, you create a forest (whether in a base mesh or overlay DSF) by creating a DSF polygon referencing a .for (forest) art asset. X-Plane will render this by filling the area inside the polygon with lots of trees.
In X-Plane 10, you will be able to optionally tell X-Plane to put the trees only on the edge of the polygon, rather than filling the entire inside. (This feature will be controlled by using values on the polygon parameter that are larger than 255, at least I think.) This will mean that you can use .for files and DSF polygon not only to create forest areas, but also to create rows of trees along the edges of roads or fields. A row of trees made by a .for file and DSF polygon will render much faster than a large number of individual OBJ-based trees.
This kind of art asset extension is similar to what we have already seen; X-Plane 850 introduced three new art asset types (.str object strings, .lin line paint, and .pol draped polygons) that all produced new rendering tricks using DSF polygons. These art assets were added to provide high performance rendering of airport surface areas. The new art assets didn’t require any change to DSF because the representation of the position of these art assets is something DSF has always done: simple polygons.
DSF won’t last forever, but at least for X-Plane 10 it looks like we can do a third full cycle of the sim using DSF as our base container format for scenery position data.
