why directx is more lower than windib?

[Guo Xu]

Hi everyone,
  I am new to SDL.
  I had compiled the example "testsprint", and tested it on my computer( Windows XP )

  But I found that
  at windows mode , the fps of windib is 20 times more than directx,
  and with -fast(fullscreen) param, the fps of directx is still at 60, but the fps of windib can come 200,
  So, who can tell me why this happen and why there are so many pepole say directx is faster than windib?

***The below is the list of results.***

>>>testsprint -width 800 -height 600 -bpp 32 -hw -flip 1000
Screen is at 32 bits per pixel
Screen is in system memory
Sprite is in system memory
Sprite blit uses RLE 
acceleration
205.80 frames per second
>>>testsprint -width 800 -height 600 -bpp 32 -hw -flip -directx 1000
Screen is at 32 bits per pixel

Screen is in system memory
Sprite is in system memory
Sprite blit uses RLE 
acceleration
10.83 frames per second
>>>testsprint -width 800 -height 600 -bpp 32 -fast 1000
Screen is at 32 bits per pixel

Screen is in system memory
Sprite is in system memory
Sprite blit uses RLE 
acceleration
195.55 frames per second
 
>>>testsprint -width 800 -height 600 -bpp 32 -fast -directx 1000
Screen is at 32 bits per pixel

Screen is in video memory
Screen has double-buffering enabled
Sprite is in video memory
Sprite blit uses hardware acceleration
59.61 frames per second

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[Gabriele Greco]

On Thu, Oct 9, 2008 at 2:50 PM, Guo Xu <goooxu@...> wrote:

>>>testsprint -width 800 -height 600 -bpp 32 -fast -directx 1000
Screen is at 32 bits per pixel


Screen is in video memory
Screen has double-buffering enabled
Sprite is in video memory
Sprite blit uses hardware acceleration
59.61 frames per second

As you can see from your tests the hardware acceleration of DirectX is used only in this test, the other test that gave 10fps is using some strange slow rendering path. 

The 60fps limit of this case may be dued to the vertical blank sync, check if your screen mode is refreshed at 60hz, and/or try to disable the sync in the GFX card drivers to see if directx can perform more than software mode, and it should be able to do so at least on XP.

--
Ing. Gabriele Greco, DARTS Engineering
Tel: [phone]  Fax: [phone]
s-mail: Via G.T. Invrea 14 - 16129 GENOVA (ITALY)

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[Guo Xu]

Hi Gabriele

   Thank you for you reply

   I cannot find the option of vertical blank sync on my "NVIDIA Control Panel" 1.5.30.22, may be I should install a newer driver.

   BTW, now a lot of large games, like WOW, both have the windows mode and fullscreen mode,

   And they also use DirectX for rendering, but their render speed in windows mode is not slower than fullscreen mode ,why?

2008/10/9 Gabriele Greco <gabriele.greco@...>

On Thu, Oct 9, 2008 at 2:50 PM, Guo Xu <goooxu@...> wrote:

>>>testsprint -width 800 -height 600 -bpp 32 -fast -directx 1000
Screen is at 32 bits per pixel



Screen is in video memory
Screen has double-buffering enabled
Sprite is in video memory
Sprite blit uses hardware acceleration
59.61 frames per second

As you can see from your tests the hardware acceleration of DirectX is used only in this test, the other test that gave 10fps is using some strange slow rendering path. 

The 60fps limit of this case may be dued to the vertical blank sync, check if your screen mode is refreshed at 60hz, and/or try to disable the sync in the GFX card drivers to see if directx can perform more than software mode, and it should be able to do so at least on XP.

--
Ing. Gabriele Greco, DARTS Engineering
Tel: [phone]  Fax: [phone]
s-mail: Via G.T. Invrea 14 - 16129 GENOVA (ITALY)

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[Gabriele Greco]

On Thu, Oct 9, 2008 at 3:23 PM, Guo Xu <goooxu@...> wrote:

Hi Gabriele

   Thank you for you reply

   I cannot find the option of vertical blank sync on my "NVIDIA Control Panel" 1.5.30.22, may be I should install a newer driver.

   BTW, now a lot of large games, like WOW, both have the windows mode and fullscreen mode,

   And they also use DirectX for rendering, but their render speed in windows mode is not slower than fullscreen mode ,why?

Those are 3d games, you can make fast 3d openGL games, fast both windowed & fullscreen with SDL, but that's a total different story since you could not use SDL_BlitSurface, SDL_FillRect and so on in GL mode.

2d acceleration of SDL at the moment is not very used nor supported, it works only on Win32 and in fullscreen mode, it uses ancient DX5 API, so in the latest version it's disabled by default.

Most 2d games works well on modern computer doing everything in software and then doing the final blit to videoram, with SDL this is the ONLY way to go if you want to use also alpha channel surfaces.

This will change with SDL 1.3/2.0 that will provide a backend for opengl/directx accelerated 2d gfx, if you feel confortable with SDL 2d API just stick with it and use software mode (IE open the window with something similar to SDL_SetVideoMode(w, h, 0, SDL_SWSURFACE)) if your game is too slow (I doubt it will) you can always try to use SDL 1.3 snapshots or the glSDL extension you can find here http://olofson.net/mixed.html.

2d acceleration provided by a 3d backend like the SDL 1.3 one or glSDL have also the big advantage that works also on Linux and Mac.

--
Bye,
 Gabry

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[Alexander Shpilkin]

The screen is redrawn at 60 fps on the hardware (i.e. actually only 60
frames are sent to the physical display) so there is _no_ actual
difference between 60fps and 200fps. You should try to time the
rendering and SwapBuffers() calls separately because SwapBuffers()
waits for the next actual frame to be sent to the hardware. And, vsync
is switched off not in
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[Guo Xu]

Thank you Gabriele and Alexander，

 I will post the result after I do a new test.

2008/10/10 Alexander Shpilkin <ashpilkin@...>

The screen is redrawn at 60 fps on the hardware (i.e. actually only 60
frames are sent to the physical display) so there is _no_ actual
difference between 60fps and 200fps. You should try to time the
rendering and SwapBuffers() calls separately because SwapBuffers()
waits for the next actual frame to be sent to the hardware. And, vsync
is switched off not in

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[Guo Xu]

Hi Gabriele, Alexander

I Installed a new nvidia driver, it can close the vertical blank sync.

And I use glSDL extension did a newer test,

here is the result:

>>>testsprint -width 800 -height 600 -bpp 32 -hw -flip 1000

Screen is at 32 bits per pixel

Screen is in system memory

Sprite is in system memory

Sprite blit uses RLE acceleration

217.93 frames per second

>>>testsprint -width 800 -height 600 -bpp 32 -hw -flip -directx 1000

Screen is at 32 bits per pixel

Screen is in system memory

Sprite is in system memory

Sprite blit uses RLE acceleration

68.63 frames per second

>>>testsprint -width 800 -height 600 -bpp 32 -hw -flip -gl 1000

Screen is at 24 bits per pixel

Screen is in system memory

Sprite is in system memory

1246.23 frames per second

>>>testsprint -width 800 -height 600 -bpp 32 -fast 1000

Screen is at 32 bits per pixel

Screen is in system memory

Sprite is in system memory

Sprite blit uses RLE acceleration

212.30 frames per second

>>>testsprint -width 800 -height 600 -bpp 32 -fast -directx 1000

Screen is at 32 bits per pixel

Screen is in video memory

Screen has double-buffering enabled

Sprite is in video memory

Sprite blit uses hardware acceleration

151.63 frames per second

>>>testsprint -width 800 -height 600 -bpp 32 -fast -gl 1000

Screen is at 24 bits per pixel

Screen is in system memory

Sprite is in system memory

1247.44 frames per second

As Gabriele said, the opengl rendering is much more faster.

And I will try to separate the rendering and swapbuffer later, it will be looked better.

Thanks a lot for your advice.

2008/10/10 Guo Xu <goooxu@...>

Thank you Gabriele and Alexander，

 I will post the result after I do a new test.

2008/10/10 Alexander Shpilkin <ashpilkin@...>

The screen is redrawn at 60 fps on the hardware (i.e. actually only 60
frames are sent to the physical display) so there is _no_ actual
difference between 60fps and 200fps. You should try to time the
rendering and SwapBuffers() calls separately because SwapBuffers()
waits for the next actual frame to be sent to the hardware. And, vsync
is switched off not in

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[c2woody]

>  But I found that
>  at windows mode , the fps of windib is 20 times more than directx,

For some to me unknown reason the hardware acceleration is
disabled for windowed mode when using the directx interface.
The commit message is very unspecific about why this was removed,
and I've not yet experienced any trouble when re-enabling hw
acceleration for windowed mode.



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