3

Windows7 is using point filtering to stretch from my DirectX9 back-buffer to the window client area. When the window is resized the artifacts from the stretching look very bad. We can avoid this by changing the back buffer size, but that requires calling IDirect3DDevice9::Reset(). This results in a black screen and a small delay while resizing is happening.

Is there any way to improve the filtering method windows uses? Or, Is there any way to update the window from a different DirectX surface such as a Render Target?

Im using unmanaged C++ DirectX code. Say I have a 1280 x 720 back buffer surface:

D3DPRESENT_PARAMETERS  presentParams;
presentParams.BackBufferWidth  = 1280;
presentParams.BackBufferHeight = 720;
gD3D->CreateDevice(
    0, D3DDEVTYPE_HAL, hWnd,               
    D3DCREATE_HARDWARE_VERTEXPROCESSING,
    &presentParams,
    &pD3D9Device);

Yet I have a 1920 x 1080 window:

hWnd = CreateWindowExA(NULL, "WindowClass", winName,
                flags, 0, 0, 1920, 1080,
                NULL, NULL, hInstance, NULL);

When I call Present() windows will stretch my DirectX back buffer to the window. However their stretch doesn't appear to perform any filtering.

pD3D9Device->Present(NULL, NULL, NULL, NULL);

I can resize the backbuffer, but that requires a call to Reset() and Reset() causes video memory surfaces to be lost.

JustinB
  • 1,532
  • 15
  • 18
  • I remvoed the `windows` and `windows-7` tags, because they're meaningless. The question is about `DirectX9`, which is obviously Windows-specific, and `DirectX` is doing the sampling/rendering, not Windows itself (if Windows did it, you wouldn't need DirectX). – Ken White Jul 13 '12 at 01:32
  • Windows is just doing the stretch blt (after rendering) to the window. – JustinB Jul 13 '12 at 01:47
  • 1
    The usual way is to make the back buffer and window the same size - if you can't change the buffer, change the window. I presume DirectX is using the fastest possible way to get the image to the window, which involves no filtering. You can minimize the distortion by making the buffer an integer division of the window size. – Mark Ransom Jul 19 '12 at 22:26
  • Yes, this makes sense. In the case where the user is resizing the window to arbitrary sizes we were trying to handle it gracefully and quickly. – JustinB Jul 20 '12 at 00:58

3 Answers3

1

I bump to this problem when I try to play video in window, and want to resize window without the need to reset device.

I found a solution from mpc-hc source code: https://github.com/mpc-hc/mpc-hc/blob/develop/src/filters/renderer/VideoRenderers/SyncRenderer.cpp

1) Make backbuffer big (biggest size that you expect the window would be)-> I chose screen size

2) Draw only on a rectangle, that size equal to the window

3) use Device.Present(srcrect, destrect). srcrect and destrect are the same rectangle and are window size.

I am new to directX and all, but this solution works for me.

Ngo Phuong Le
  • 440
  • 6
  • 9
0

It would be helpful if you posted some code fragments of the specific operations you're asking about, however if you are using the GDI (Unmanaged Win32) StretchBlt function, you can get better resizing behavior with HALFTONE, as per this post: Is StretchBlt HALFTONE == BILINEAR for all scaling?

If you are using GDI+ (WinForms/C#), you can get Bilinear (or better) interpolation using g.InterpolationMode = InterpolationMode.Bilinear (look at MSDN for all options). Be warned that GDI+ is typically slower than GDI (or DX)

(Somewhat related info in this post: Bilinear interpolation - DirectX vs. GDI+)

Community
  • 1
  • 1
holtavolt
  • 4,378
  • 1
  • 26
  • 40
  • Thanks for the information. However I am not using GDI, just DirectX. Im just trying to avoid resizing my backbuffer in DirectX, but it seems this is the only way to go. – JustinB Jul 19 '12 at 21:12
0

Have you tried the IDirect3DDevice9::SetSamplerState?

http://msdn.microsoft.com/en-us/library/windows/desktop/bb174698(v=vs.85).aspx

Actually I was searching around for a similar issue I had. I used D3D9 texture to render some images. On Vista, the SetSamplerState plus Linear Texture Filtering helps reducing the artifacts caused by resizing windows a lot. But this is not the case on Windows7. I'm not sure how this is handled differently in the 2 platforms.

Jerry
  • 1