Author Topic: Add support for custom refresh rates (Read 22339 times)

Tungsten · « **on:** November 07, 2008, 02:45:55 pm »

If you are using a CRT-monitor it will default to 60 Hz when using fullscreen mode. Instead of using a refresh rate locker for certain resolutions add a member to the VideoMode class.

VideoMode.hpp
Add an unsigned int DisplayFreq member.

Code: [Select]


    unsigned int Width;        ///< Video mode width, in pixels
    unsigned int Height;       ///< Video mode height, in pixels
    unsigned int BitsPerPixel; ///< Video mode pixel depth, in bits per pixels
    unsigned int DisplayFreq;  ///< Video mode display frequency

Change the constructor to take a DisplayFreq parameter(defaults to 60 if not specified).

Code: [Select]


VideoMode::VideoMode(unsigned int ModeWidth, unsigned int ModeHeight, unsigned int ModeBpp, unsigned int ModeFreq) :
Width       (ModeWidth),
Height      (ModeHeight),
BitsPerPixel(ModeBpp),
DisplayFreq(ModeFreq)

I have implemented it for the win32 platform

VideoModeSupport.cpp

In the GetSupportedVideoModes method add the DisplayFrequency argument to the constructor call.

Code: [Select]


VideoMode Mode(Win32Mode.dmPelsWidth,Win32Mode.dmPelsHeight,
               Win32Mode.dmBitsPerPel,Win32Mode.dmDisplayFrequency);

VideoMode.cpp

Change the overloaded comparison operator to

Code: [Select]


return  (Width        == Other.Width)        &&
        (Height       == Other.Height)       &&
        (BitsPerPixel == Other.BitsPerPixel) &&
        (DisplayFreq  == Other.DisplayFreq);

so it can fail if a too high refresh rate was selected.

WindowImpWin32.cpp

In the SwitchToFullscreen method add

Code: [Select]


DevMode.dmDisplayFrequency	= Mode.DisplayFreq;
DevMode.dmFields			    = DM_PELSWIDTH | DM_PELSHEIGHT | DM_BITSPERPEL | DM_DISPLAYFREQUENCY;

so it can change the frequency when the call to ChangeDisplaySettings is made.

zarka · « **Reply #1 on:** November 07, 2008, 09:26:53 pm »

Quote from: "Tungsten"

If you are using a CRT-monitor it will default to 60 Hz when using fullscreen mode. Instead of using a refresh rate locker for certain resolutions add a member to the VideoMode class.

A better solution would be to use the refresh rate currently selected by the user.. or you will probably be hated by all the gamers that play your game that have a monitor capable of higher refresh rates. That makes it safer to use to. in case someone has a monitor that does not support 60hz

Tungsten · « **Reply #2 on:** November 07, 2008, 10:20:14 pm »

Uh , i think you misunderstood that statement.

The current svn-version of sfml will default back to 60hz no matter what refresh rate you use in desktop mode. You will always end up with 60 hz in fullscreen mode.

The change adds support for the user to specify the refresh rate used in fullscreen mode nothing else. If the specified refresh rate is not a supported mode it will fail and default back to the "best" mode supported by the card.

If you do not specify a value it will be set to 60. If that is not a supported refresh rate(which is highly unlikely) it will also fail and default back to the "best" mode supported by the card. That functionality is already implemented in sfml by the IsValid() method in the VideoMode class.

Of course you can change the behaviour so if no refresh rate value is specified it will try to pick the current desktop refresh rate but that might also fail if you use a different fullscreen resolution compared to your desktop resolution.

zarka · « **Reply #3 on:** November 08, 2008, 11:41:18 am »

Quote from: "Tungsten"

Uh , i think you misunderstood that statement.

The current svn-version of sfml will default back to 60hz no matter what refresh rate you use in desktop mode. You will always end up with 60 hz in fullscreen mode.

The change adds support for the user to specify the refresh rate used in fullscreen mode nothing else. If the specified refresh rate is not a supported mode it will fail and default back to the "best" mode supported by the card.

If you do not specify a value it will be set to 60. If that is not a supported refresh rate(which is highly unlikely) it will also fail and default back to the "best" mode supported by the card. That functionality is already implemented in sfml by the IsValid() method in the VideoMode class.

Of course you can change the behaviour so if no refresh rate value is specified it will try to pick the current desktop refresh rate but that might also fail if you use a different fullscreen resolution compared to your desktop resolution.

Aaaah i see

and now i agree with you

Laurent · « **Reply #4 on:** November 08, 2008, 09:34:17 pm »

This is not the expected behaviour. On Windows, I change only the width, height and bits per pixel. So the frequency is not supposed to change. Did you try on other computers, to make sure this behaviour was consistent ?

Tungsten · « **Reply #5 on:** November 09, 2008, 01:33:07 pm »

I actually think that is the expected behaviour if you do not specify a value for the dmDisplayFrequency member of the DEVMODE structure.

The ChangeDisplaySettings function will default to what is considered a "compatible" refresh rate for the device if not specified. It's a non-issue for LCD screens because they use a fixed 60 Hz frequency.

Laurent · « **Reply #6 on:** November 09, 2008, 07:25:26 pm »

Quote

I actually think that is the expected behaviour if you do not specify a value for the dmDisplayFrequency member of the DEVMODE structure

I can't see anything saying this in the MSDN. I just see that there's a parameter where you specify what properties to change, so I assume the others won't be modified.

SephiRok · « **Reply #7 on:** July 27, 2009, 12:38:58 am »

Quote from: "Laurent"

This is not the expected behaviour. On Windows, I change only the width, height and bits per pixel. So the frequency is not supposed to change. Did you try on other computers, to make sure this behaviour was consistent ?

My friend has the same problem.

blewisjr · « **Reply #8 on:** July 27, 2009, 01:07:23 am »

I think that might be the default behavior. Most LCD monitors actually use 60HZ frequency in windowed mode and 75HZ in fullscreen actually tho.

SephiRok · « **Reply #9 on:** July 27, 2009, 01:10:50 am »

Windowed mode depends on the desktop refresh rate.

When switching to fullscreen you get forced to 60, even if your desktop is 75.

blewisjr · « **Reply #10 on:** July 27, 2009, 01:13:21 am »

Opse had it backwards

Calmatory · « **Reply #11 on:** October 05, 2009, 11:59:58 am »

Any further information on "solving" this issue?

Laurent · « **Reply #12 on:** October 05, 2009, 12:47:50 pm »

No, sorry.

Antidote · « **Reply #13 on:** November 09, 2009, 07:51:21 am »

LCDs DON'T use Hz they use Reponse Time (Measured in milliseconds), and it DOESN'T change when the application is in fullscreen or in windowed, i don't know where you got this information but it's wrong.

SephiRock is correct, windowed mode is dependent on the Desktop settings, and you are forced in to 60Hz when in fullscreen.

dunce · « **Reply #14 on:** November 10, 2009, 05:12:34 am »

The last post here was more than a month ago. What's the need to dig up this topic just to discuss LCD monitors.

Quote

LCDs DON'T use Hz they use Reponse Time (Measured in milliseconds)

Refresh rate has nothing to do with response time. They are different physical characteristics. LCDs have both. Response time denotes dynamic capability of LCD cells (how fast they can change their state). LCDs DO use Hz (saying your words). For example my old crappy Samsung has three available rates (60, 70, 72 Hz). And I can choose any of them. BTW, a monitor itself, no matter CRT or LCD, knows nothing about windowed or fullscreen mode. These are OS & videodriver that control its behaviour.