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chpstcks

OpenGL [edit] choppy panning animation

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hello, I am creating a maximized windowed application (meaning that it plays nice with other windowed application, but occupies the whole screen and does not change the resolution) that pans large textured rectangle (close to 1600x1200) across the screen. My frame rate is decent enough (capped at 35fps), and movement rate is constant. However, the animation is still choppy (it's not unbearable, but just not up to par)... I have the identical app implemented in OpenGL (with frame rate capped at 30) and the animation is far smoother. i logged the application and the biggest difference between the two version is that blt in directx (have to use dx7 for compatibility =/ ) is way slower than SwapBuffers in the opengl version. Whereas swapbuffers takes about 5-15ms per frame, blt/bltfast averages at 25ms. any insights or ideas on why this is the case would be greatly appreciated ^^;; thanks, ~dAviD [Edited by - chpstcks on November 30, 2006 4:02:22 PM]

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If you're doing it in 3D using textured quads in OpenGL, I think it will almost certainly be faster than blitting using DirectDraw.

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OpenGL will use hardware for rendering, DirectDraw will almost certainly be software. The equivalent to OpenGL would be Direct3D, not DirectDraw - and you should get performance pretty much identical to OpenGL.

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Quote:
Original post by Evil Steve
OpenGL will use hardware for rendering, DirectDraw will almost certainly be software. The equivalent to OpenGL would be Direct3D, not DirectDraw - and you should get performance pretty much identical to OpenGL.


hmmm... well, I'm using direct3d to draw quads to the offscreen surface, then blt'ing it to the primary; wasn't aware there's another way to do this.... or am i just confused? o_O

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Quote:
Original post by chpstcks
Quote:
Original post by Evil Steve
OpenGL will use hardware for rendering, DirectDraw will almost certainly be software. The equivalent to OpenGL would be Direct3D, not DirectDraw - and you should get performance pretty much identical to OpenGL.


hmmm... well, I'm using direct3d to draw quads to the offscreen surface, then blt'ing it to the primary; wasn't aware there's another way to do this.... or am i just confused? o_O
It's been years since I used DDraw - If you're fullscreen, you can flip the surfaces I think. In windowed mode you need to blit the backbuffer to the window, yes.

However, there shouldn't be much of a speed difference between D3D and OpenGL if things are done correctly. I imagine OpenGL has to do something similar to what D3D does behind the scenes too...

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Quote:
Original post by Evil Steve
It's been years since I used DDraw - If you're fullscreen, you can flip the surfaces I think. In windowed mode you need to blit the backbuffer to the window, yes.

However, there shouldn't be much of a speed difference between D3D and OpenGL if things are done correctly. I imagine OpenGL has to do something similar to what D3D does behind the scenes too...


Right, SwapBuffers does functionally the same thing for OpenGL in Windows as Blt does for directX. My blt speed doesn't seems to be dependent on what i'm blt'ing, but what size the primary surface is... i can blt from a 32x32 back surface to a 1200x1600 front surface (or even a blank screen) and it still takes 25ms. I guess this is expected since it's just copying pixels across buffers... i tried messing around with DDBLTFX struct but doesn't seem to matter >_<

is there any reason to believe using IDirect3DDevice8::Present() will be faster than IDirectDrawSurface7::Blt() ?

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Yes, because it will render in 3D using 3D Hardware. Let me see if I have this correct: you're using Direct3D to render textured quads to a surface, then using DirectDraw to blit it to the screen? Why not just use Direct3D to render it to the backbuffer?

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Quote:
Original post by Sc4Freak
Yes, because it will render in 3D using 3D Hardware. Let me see if I have this correct: you're using Direct3D to render textured quads to a surface, then using DirectDraw to blit it to the screen? Why not just use Direct3D to render it to the backbuffer?


i do render the rectangle to the back buffer using direct3D, but i still have to blt it to the primary surface since it's a windowed app. So you guys seem to be suggesting that Blt, even with the right flags set, will use software to render rather than hardware? Doesn't that mean all windowed 3D app before Dx8 used software blitting?? o_O?? just seems so strange...

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I played with my app some more and was able to reach a frame rate of ~150fps by giving it exclusive access to the screen... but the panning is STILL not smooth!

So this points to a settings problem rather than a blt problem, but i went through all the render states and texture stage states and i just can't get it to pan smoothly >___<

please help~

i have the following set:

m_pd3dDevice->SetRenderState(D3DRENDERSTATE_AMBIENT, 0xffffffff );
m_pd3dDevice->SetRenderState( D3DRENDERSTATE_ANTIALIAS, D3DANTIALIAS_SORTINDEPENDENT );
m_pd3dDevice->SetRenderState(D3DRENDERSTATE_EDGEANTIALIAS , D3DANTIALIAS_SORTINDEPENDENT );
m_pd3dDevice->SetRenderState( D3DRENDERSTATE_TEXTUREPERSPECTIVE, FALSE );

m_pd3dDevice->SetTextureStageState( 0, D3DTSS_COLORARG1, D3DTA_TEXTURE );
m_pd3dDevice->SetTextureStageState( 0, D3DTSS_COLORARG2, D3DTA_DIFFUSE );
m_pd3dDevice->SetTextureStageState( 0, D3DTSS_COLOROP, D3DTOP_MODULATE );
m_pd3dDevice->SetTextureStageState( 0, D3DTSS_MINFILTER, D3DTFN_LINEAR );
m_pd3dDevice->SetTextureStageState( 0, D3DTSS_MAGFILTER, D3DTFG_LINEAR );
m_pd3dDevice->SetTextureStageState( 0, D3DTSS_ADDRESS, D3DTADDRESS_CLAMP);

//i tried the notearing flag for blt and that didn't help either

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