Howto:Improve framerates: Difference between revisions

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=Frame Rates=
=Frame Rates=
Anything below about 15 frames per second (fps) is close to unusable, or at least, will not be enjoyable.
Anything below about 15 frames per second (fps) is close to unusable, or at least, will not be enjoyable.  
Additionally, the more the framerate decreases, the more other features of the simulation will suffer. The current [[FlightGear]] software architecture is such that long rendering times (slow framerates) may prevent other parts of the flight simulator, such as the autopilot, from having sufficient CPU time to respond correctly in the context of the simulation.
Additionally, the more the framerate decreases, the more other features of the simulation will suffer. The current [[FlightGear]] software architecture is such that long rendering times (slow framerates) may prevent other parts of the flight simulator, such as the autopilot, from having sufficient CPU time to respond correctly in the context of the simulation.


FlightGear's framerate is influenced by various factors, including:
FlightGear's framerate is influenced by various factors, including:
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You can disable most features that often adversely affect framerate. Here is a collection of settings that you may change to improve your framerate. Please note that some of these will only take effect if they're specified at startup and cannot be changed after the simulation has started.
You can disable most features that often adversely affect framerate. Here is a collection of settings that you may change to improve your framerate. Please note that some of these will only take effect if they're specified at startup and cannot be changed after the simulation has started.


==3D Models==
== 3D Models ==
Contrary to what many people believe, the impact of high vertex-count models on framerate is fairly minimal. In addition, for graphics hardware built after 2004 and intended for games (example: Nvidia GeForce 6 series), textures are close to, or completely, free. Today (in 2010), the major graphics bottleneck is between the CPU and the GPU. The goal in optimizing models is to store as much as possible on the GPU and reduce the number of rendering commands sent to the GPU. For graphic artists, the key things to remember are:
Contrary to what many people believe, the impact of high vertex-count models on framerate is fairly minimal. In addition, for graphics hardware built after 2004 and intended for games (example: Nvidia GeForce 6 series), textures are close to, or completely, free. Today (in 2010), the major graphics bottleneck is between the CPU and the GPU. The goal in optimizing models is to store as much as possible on the GPU and reduce the number of rendering commands sent to the GPU. For graphic artists, the key things to remember are:


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* Don't assign an RGBA texture to a model that is completely opaque!
* Don't assign an RGBA texture to a model that is completely opaque!


==Other Windows/Programs==
== Other Windows/Programs ==
Don't run Flightgear while also running another application, except if you need it. The two programs are competing for the CPU's proccessing power. As a basic rule, try to minimize the amount of programs open, so Flightgear can have the biggest portion of the CPU Times. Graphics-intensive programs also drain the GPU/graphics card, so you may be able to add a few frames.
Don't run Flightgear while also running another application, except if you need it. The two programs are competing for the CPU's proccessing power. As a basic rule, try to minimize the amount of programs open, so Flightgear can have the biggest portion of the CPU Times. Graphics-intensive programs also drain the GPU/graphics card, so you may be able to add a few frames.


==AI traffic==
== AI traffic ==
[[Interactive Traffic|AI-traffic]] is computer controlled traffic, which includes traffic over the [[Howto: Multiplayer|MP network]]. By turning off this function you're not able to see other aircraft.  
[[Interactive Traffic|AI-traffic]] is computer controlled traffic, which includes traffic over the [[Howto: Multiplayer|MP network]]. By turning off this function you're not able to see other aircraft.  


Most stuttering, or lag, in FlightGear is caused by AI traffic. Especially heavy models need quite some time to load, eg the [[Grumman F-14 Tomcat|F-14]] or the [[Rockwell B-1B Lancer|B-1B]]. Every time a new aircraft enters your local area, your computer has to load the model for that particular aircraft. The time required to read the data from the drive creates a stutter, or lag, which can range from a minor annoyance to a crash. The busier the place you fly, the more lag you'll get; eg flying around KSFO will generate more lag than a flight near EGLL, since there is more traffic near KSFO.
Most stuttering, or lag, in FlightGear is caused by AI traffic. Especially heavy models need quite some time to load, eg the [[Grumman F-14 Tomcat|F-14]] or the [[Rockwell B-1B Lancer|B-1B]]. Every time a new aircraft enters your local area, your computer has to load the model for that particular aircraft. The time required to read the data from the drive creates a stutter, or lag, which can range from a minor annoyance to a crash. The busier the place you fly, the more lag you'll get; eg flying around KSFO will generate more lag than a flight near EGLL, since there is more traffic near KSFO.


==Outside vs. Inside Views==
== Outside vs. Inside Views ==
One of the things that can also affect the frame rate is the view. The inside cockpit view is better than the outside views, like Tower View (especially KSFO) and Chase view without Yaw. Once inside, the GPU and/or graphics card does not have to draw scenery. But if the cockpit is 3D and really detailed, performance is about the same.
One of the things that can also affect the frame rate is the view. The inside cockpit view is better than the outside views, like Tower View (especially KSFO) and Chase view without Yaw. Once inside, the GPU and/or graphics card does not have to draw scenery. But if the cockpit is 3D and really detailed, performance is about the same.


==Operating System Specific==
== Operating System Specific ==
Many newer Linux distributions, like openSUSE 11.2, come with KDE4 as a desktop environment. While it allows some fancy desktop effects, it is known to consume enough computing power from the CPU and the graphics card to slow FlightGear down by 10 frames per second or even more. Choosing another window manager from the login screen, like xfce results in higher FlightGear performance. Setting "Compositing" to "off" in KDE4 might also help.
Many newer Linux distributions, like openSUSE 11.2, come with KDE4 as a desktop environment. While it allows some fancy desktop effects, it is known to consume enough computing power from the CPU and the graphics card to slow FlightGear down by 10 frames per second or even more. Choosing another window manager from the login screen, like xfce results in higher FlightGear performance. Setting "Compositing" to "off" in KDE4 might also help.


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