Celestia Forums

I setup Celestia under Linux this week to gain an insight into both the performance and rendering differences. There are quite a few differences in Celestia under Fedora and Vista.

- Performance: Linux users are provided with a smoother experience. Under Vista graphics can be somewhat glitchy and momentary stalls are common when textures are being loaded. In Linux, the rendering is smooth and the program never stalls using its default setup.

- Realism - Vista provides a better sense of realism. The lighting is more natural and this adds increased depth to the scene. Under Linux, the scene can look a little to bleached and the lighting can be very sharp. I tried playing around with the settings of the graphics card, but this didn't change things much. (Note: This could be a driver issue.)

- Effects - Linux users get better visual effects, such as lighting around the sun and subtle tone differences between stars. The majority of these effects don't render properly under Windows. For example, under Windows a given star was yellow, the same star under Linux had a slight red tint to it.

- FPS - The frame count under Linux was consistantly 10-20% higher than under Vista.

The one thing I found annoying was the different menu system under Linux. This lack of cross-OS consistancy meant having to re-learn the location of certain commands. In full screen mode, the menu bar does not disappear and destroys the immersive experience.

Anyone else notice any differences?

DT wrote:I setup Celestia under Linux this week to gain an insight into both the performance and rendering differences. There are quite a few differences in Celestia under Fedora and Vista.

- Performance: Linux users are provided with a smoother experience. Under Vista graphics can be somewhat glitchy and momentary stalls are common when textures are being loaded. In Linux, the rendering is smooth and the program never stalls using its default setup.

- Realism - Vista provides a better sense of realism. The lighting is more natural and this adds increased depth to the scene. Under Linux, the scene can look a little to bleached and the lighting can be very sharp. I tried playing around with the settings of the graphics card, but this didn't change things much. (Note: This could be a driver issue.)

These statements I find way too generic to be useful. Firstly, you did NOT set out to specify which Linux version of Celestia you were using (KDE, GNOME or GTK). Next you did not specify what graphics card you were using. In case of NVIDIA, the driver architecture is UNIVERSAL, hence equal versions for Linux and Vista should most probably give almost the same results. Since the issue is quite different with ATI, your statements need substantial clarification.

- Effects - Linux users get better visual effects, such as lighting around the sun and subtle tone differences between stars. The majority of these effects don't render properly under Windows. For example, under Windows a given star was yellow, the same star under Linux had a slight red tint to it.

I doubt that this should be a real difference being NOT due to further required adjustments.

- FPS - The frame count under Linux was consistantly 10-20% higher than under Vista.

That's what most of us understand, I suppose . You sure know about the level of OpenGL implementation in Vista...?

The one thing I found annoying was the different menu system under Linux. This lack of cross-OS consistancy meant having to re-learn the location of certain commands. In full screen mode, the menu bar does not disappear and destroys the immersive experience.

• Christophe Teyssier in the dev team is working since some time to achieve cross-platform GUI compilation based on the new KDE4 toolkit.
  
• As a developer, I am using both Windows and Linux GUIs in parallel and never had any particular problem using both. Most people just use ONE GUI and thus won't notice much about such OS-specific differences.
  
• Of course, the menu bar can be made to vanish in Linux GUI's as well. You just type CTRL+M, the standard KDE command to make menu bars vanish.
  
  As in any KDE standard application, in Celestia-KDE, the key-shortcuts can of course be re-programmed to personal gusto! So what's the point, here, really?

Bye Fridger

These statements I find way too generic to be useful. Firstly, you did NOT set out to specify which Linux version of Celestia you were using (KDE, GNOME or GTK). Next you did not specify what graphics card you were using. In case of NVIDIA, the driver architecture is UNIVERSAL, hence equal versions for Linux and Vista should most probably give almost the same results. Since the issue is quite different with ATI, your statements need substantial clarification.

Perhaps that's because I tried each of the environments and video cards. It was the same result. Why would the be any difference in OpenGL performance between KDE or Gnome?

OpenGL is identical in both. The only real difference is widgets and that's not likely to slow things down.

I doubt that this should be a real difference being NOT due to further required adjustments.

Yeah, well it is...

That's what most of us understand, I suppose . You sure know about the level of OpenGL implementation in Vista...?

Yes, 1.4 as part of the OS and full 2.0 as part of the driver ICD...there is no reason why the rendering should be 10-20% slower.

Christophe Teyssier in the dev team is working since some time to achieve cross-platform GUI compilation based on the new KDE4 toolkit.

I think that is a waste. The menu system is visually repulsive. Vincent's overlays are much better.

As a developer, I am using both Windows and Linux GUIs in parallel and never had any particular problem using both. Most people just use ONE GUI and thus won't notice much about such OS-specific differences.

Consistancy is important. Not only does it make development easier, it helps those that do transition between platforms.

Of course, the menu bar can be made to vanish in Linux GUI's as well. You just type CTRL+M, the standard KDE command to make menu bars vanish.

Yeah, but it doesn't happen be default. Its just inconsistant.

As in any KDE standard application, in Celestia-KDE, the key-shortcuts can of course be re-programmed to personal gusto!

I do realise this...

So what's the point, here, really?

You're beginning to sound like an ex-girlfriend...

The point is cross-OS development should not be taking different paths to a solution. There should be consistancy and minimal difference in code.

DT wrote:You're beginning to sound like an ex-girlfriend...

The point is cross-OS development should not be taking different paths to a solution. There should be consistancy and minimal difference in code.

If I sound like an ex-girlfriend, you sound like an "old wise man with a beard" lecturing to his students

Don't forget that our decisions about the GUI toolkits and respective cross-platform opportunities had to be made > 5 years ago, when a number of alternatives of today were unavailable. Many of us think that the GUI of Celestia-KDE is most advanced and can be ported to cross-platform KDE4 level with least effort,

DT wrote:I think that (KDE4) is a waste.

and certainly Christophe Teyssier usually does not WASTE his time... Of course you are free to do what you please, but a number of the devs tend to listen to him sometimes .

Also Celestia-KDE stores all adjustments, such that in my personal Celestia-KDE the menu bar is never visible. Again I don't know what you were arguing above. Celestia-KDE also features a great GUI bookmark toolbar with little iconic images for each retrievable bookmark configuration. These are features one does not want to miss later.

Why would there be any difference in OpenGL performance between KDE or Gnome?

Note that in my post I did of course NOT imply that the various Linux flavours would differ as to OpenGL! BUT: The precise conditions under which a comparison has been made should ALWAYS be specified as a matter of principle and to render the results useful also at a later stage. What I had in mind were issues that you discussed further below. There, indeed, there are significant differences depending on the Linux flavor considered! A graphical bookmark manager is lacking in the gnome/gtk version, for example. And quite a bit more is different ...

Bye Fridger

Surprisingly, most of what you said were fair enough comments.

I'm still all for Vincent's overlays though. I think it is a lot cleaner. It also looks more professional. There is no reason that all the features that you would like cannot be implemented in this fashion. It makes it a little easier to expand too.

I really think it should be seriously considered.

DT wrote:I'm still all for Vincent's overlays though. I think it is a lot cleaner. It also looks more professional. There is no reason that all the features that you would like cannot be implemented in this fashion. It makes it a little easier to expand too.

I really think it should be seriously considered.

Ha, we've had this argument so many times before... To sum it up, there are two philosophies to cross-platform applications. Either you take the all OpenGL path, the one used for most games and Stellarium for example, or you go for a cross-platform toolkit like GTK, Qt or wxWidget.

If you take the first approach you have to implement your own toolkit which will obviously be less complete and more buggy than a widely used and supported toolkit. This will also take development time away from the core of the project. You do get a uniform GUI across platforms but who cares? People usualy use one platform, it's supposedely better to provide a GUI that integrates with their environment and with which they are already familliar.

For me the main downside of an OpenGL GUI is the time it would take to develop, you're cutting yourself from the facilities provided by the platform: the open/save dialog, the bookmark manager, the shortcut and toolbar manager, the configuration dialog, the documentation browser, etc... all that would have to be redeveloped, it's not a small task.

But if you think that you're up to it and that you can bring a pure OpenGL GUI to the feature level of the current KDE interface in a reasonnable timeframe then go ahead, I'm sure it would be welcomed by the community.

Ha, we've had this argument so many times before... To sum it up, there are two philosophies to cross-platform applications. Either you take the all OpenGL path, the one used for most games and Stellarium for example, or you go for a cross-platform toolkit like GTK, Qt or wxWidget.

I'm aware that the options are limited when it comes to interfaces. I've faced the problem many times.

If you take the first approach you have to implement your own toolkit which will obviously be less complete and more buggy than a widely used and supported toolkit. This will also take development time away from the core of the project. You do get a uniform GUI across platforms but who cares? People usualy use one platform, it's supposedely better to provide a GUI that integrates with their environment and with which they are already familliar.

To be honest, the majority of the features have already been implemented by Vincent. Its just a matter of structuring that into a slick UI.

As for being buggy, I don't agree with that at all. Perhaps if the coder is doing a poor job, but for the most part there is very little that you can do wrong.

In terms of taking time away, again that's not something I would agree with either. Writing and maintaining code for several different versions of the same menu system only adds time to the development process. It really makes a farce out of the concept of re-usable code.

For me the main downside of an OpenGL GUI is the time it would take to develop, you're cutting yourself from the facilities provided by the platform: the open/save dialog, the bookmark manager, the shortcut and toolbar manager, the configuration dialog, the documentation browser, etc... all that would have to be redeveloped, it's not a small task.

Not everything has to be redeveloped. Merely the front-end to each of those functions. I'm not saying 'get rid of the open/save dialog', but rather, the button that activates it should be OpenGL. This provides a common interface regardless of which platform is being used.

In time, it would be nice to replicate everything within OpenGL, but I see that as a slightly longer term goal.

But if you think that you're up to it and that you can bring a pure OpenGL GUI to the feature level of the current KDE interface in a reasonnable timeframe then go ahead, I'm sure it would be welcomed by the community.

One thing at a time.

I'm writing a back-end server at the moment and trying to design it in such a fashion that it will be able to load-balance in the future without requiring a complete redesign.

I'm just gathering opinions at this point.

t00fri wrote:[*]Of course, the menu bar can be made to vanish in Linux GUI's as well. You just type CTRL+M, the standard KDE command to make menu bars vanish.

As in any KDE standard application, in Celestia-KDE, the key-shortcuts can of course be re-programmed to personal gusto! So what's the point, here, really?

Just curious, are these points specific to KDE on Linux, or to any Qt 4 apps on
Windows, Linux, Mac? I'm getting confused here as to?€€whether "KDE4" is
referring to "Qt 4" or "Linux KDE".

dirkpitt wrote:Just curious, are these points specific to KDE on Linux, or to any Qt 4 apps on
Windows, Linux, Mac? I'm getting confused here as to?€€whether "KDE4" is
referring to "Qt 4" or "Linux KDE".

These are KDE specific. But one of the main advances of KDE4 is that it will be cross-platform (not the desktop, just the libs) so it should be possible to get Celestia-kde4 to work on Windows and OSX.

DT wrote:As for being buggy, I don't agree with that at all. Perhaps if the coder is doing a poor job, but for the most part there is very little that you can do wrong.

It does add to code complexity, so yes there are more places where things can go wrong.

DT wrote:In terms of taking time away, again that's not something I would agree with either. Writing and maintaining code for several different versions of the same menu system only adds time to the development process. It really makes a farce out of the concept of re-usable code.

That's only true to a certain extent since coders are not fully versatile, the time spent on a win32 or OSX interface can not necessarily be spent on the OpenGL and math engine. On the other hand, someone working on an OpenGL toolkit could certainly be working on inproving the rendering in other ways.

DT wrote:One thing at a time. :wink:

I'm writing a back-end server at the moment and trying to design it in such a fashion that it will be able to load-balance in the future without requiring a complete redesign.

I hope you're keeping that cross-platform too?

Christophe wrote:But one of the main advances of KDE4 is that it will be cross-platform (not the desktop, just the libs) so it should be possible to get Celestia-kde4 to work on Windows and OSX.

That would be great, I'm curious to see it compile and run on the non-Linux platforms.

Well as for security ...I don't really know much about Vista. Except I don't like it. It doesn't seem like there is much difference between it an xp besides navigating it. I also suppose that any computer that is always being run from the root/ administrator account is not secure. That is my understanding of why linux is secure and relatively virus safe. You are not root so you don't have the privilige of installing virii , but I am a n00b and my view is probably over simplified. I have had lots of trouble with vista ( at least as much trouble as having to learn linux)
Vista costs a butt load of money, has problems with apps, and is all about drm.
linux. not quite as much native hardware support, you need to read more...well more than vs. xp , but vista has lots o' problems too so maybe you have to read as much as you do in linux for vista.

vista: pretty and getting more stable ..newest service pack frees up a lot of resources.

Linux: hands down has the best eye-candy out there ( compiz-fusion)
Open source so not only is it free but the source code is released so programmers worldwide are always fixing, tweaking, and updating it to make a better and better os.

Well in conclusion as far as security goes although it may appear to the average person that windows is everwhere *nix servers run the world, and that can't be because Windows is more secure.

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