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Render directx in only a portion of a window


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#1 noatom   Members   -  Reputation: 782

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Posted 21 February 2014 - 04:33 PM

So if I want to make a windowed app that has directx in a portion of it, how would I do that? Usually directx just takes the whole window.



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#2 aregee   Members   -  Reputation: 1019

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Posted 21 February 2014 - 06:03 PM

In OpenGL, it is done with glViewport.  Searching the net, I see that DirectX equivalent is SetViewport.



#3 Buckeye   Crossbones+   -  Reputation: 4582

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Posted 21 February 2014 - 07:36 PM

Your best results will be to render to the full buffer and set a rectangular area of the client window in the Present function.

RECT vRect;
GetClientRect(hwnd,&vRect);

... render your scene up to device->EndScene();
// present the buffer to the upper right corner of the window
RECT pRect;
pRect.left = vRect.right/2;
pRect.right = vRect.right;
pRect.top = 0;
pRect.bottom = vRect.bottom/2;
device->Present(0,&pRect, 0, 0);

Be sure to present the buffer with the same aspect ratio of the buffer, otherwise the presentation will be stretched or squashed.


Edited by Buckeye, 21 February 2014 - 07:38 PM.

Please don't PM me with questions. Post them in the forums for everyone's benefit, and I can embarrass myself publicly.


#4 andur   Members   -  Reputation: 578

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Posted 21 February 2014 - 09:35 PM

Just add a smaller control that is the portion of the window you want to render to and use its HWND instead of the main window's HWND.



#5 Buckeye   Crossbones+   -  Reputation: 4582

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Posted 21 February 2014 - 09:53 PM

Actually, andur's suggestion will probably work better for you. Just create a child window of the main window. You can resize and position the child wherever you'd like within the client area. Build the viewport and projection matrix using the child's client size and aspect ratio. In the render routine:

RECT cRect;
GetClientRect(hChildWindow,&cRect);

... do your rendering

device->Present( &cRect, &cRect, hChildWindow, 0 ); // assumes viewport set to child client size

Edited by Buckeye, 21 February 2014 - 09:54 PM.

Please don't PM me with questions. Post them in the forums for everyone's benefit, and I can embarrass myself publicly.


#6 noatom   Members   -  Reputation: 782

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Posted 22 February 2014 - 06:58 AM

but isn't there any way to set the backbuffer height and width? i tried setting them but they just occupy the whole window. And without manually setting them, my aspect ratio will be hard to estimate.

 

 

EDIT: Just used a viewport.


Edited by noatom, 22 February 2014 - 07:10 AM.


#7 Buckeye   Crossbones+   -  Reputation: 4582

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Posted 22 February 2014 - 08:58 AM


without manually setting them, my aspect ratio will be hard to estimate

As long as the backbuffer width/height is larger than the child window's client width/height you'll be fine. Just don't render to the entire backbuffer.

 

They are a couple approaches but the simplest would be:

Get the child's client rect.

 

RECT cRect;

GetClientRect(hChildWnd,&cRect);

 

Set the viewport to the child's rect size. // sets the portion of the backbuffer to render to.

 

Set the view to whatever you want.

 

Set the projection with the aspect ratio of the child. aspect = (float)cRect.width/(float)cRect.height.

 

Draw the scene

 

device->Present( &cRect, &cRect, hChildWnd, 0 ); // present the cRect area of the backbuffer to the cRect area of the child window

 

EDIT: Yes, setting the viewport properly is the key.


Edited by Buckeye, 22 February 2014 - 09:04 AM.

Please don't PM me with questions. Post them in the forums for everyone's benefit, and I can embarrass myself publicly.


#8 aregee   Members   -  Reputation: 1019

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Posted 22 February 2014 - 08:59 AM

Reading the other comments here, I will retract my answer, assuming you won't be rendering in the other parts of the screen as well - then it stands.  In retrospect, it seem the solution you are seeking is the answer given by andur.



#9 8up tuotlo   Members   -  Reputation: 120

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Posted 23 February 2014 - 02:44 AM

D3DVIEWPORT9 Viewport;
 
Viewport.X = 0;
Viewport.Y = 0;
Viewport.Width  = 200;
Viewport.Height = 200;
Viewport.MinZ   = 0.0f;
Viewport.MaxZ   = 1.0f;
 
d3ddev->SetViewport(&Viewport);


#10 noatom   Members   -  Reputation: 782

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Posted 23 February 2014 - 03:59 AM

Yea apparently using a viewport won't work since the backbuffer will still be created by default to fill the entire window. You simply cannot specify a custom buffer size. So,by using a viewport you will have all the space that is nonrendered black, and if you decide to put buttons or other controls in that space, there will be problems with rendering.

 

The only solution is to actually render in a control like a tab.



#11 Buckeye   Crossbones+   -  Reputation: 4582

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Posted 23 February 2014 - 07:41 AM

Yea apparently using a viewport won't work since the backbuffer will still be created by default to fill the entire window. You simply cannot specify a custom buffer size. So,by using a viewport you will have all the space that is nonrendered black, and if you decide to put buttons or other controls in that space, there will be problems with rendering.

 

The only solution is to actually render in a control like a tab.

Not true at all.

the backbuffer will still be created by default to fill the entire window

It may be the size of the client area, but it doesn't have to fill it.

by using a viewport you will have all the space that is nonrendered black

Irrelevant. Don't present the non-rendered area.

if you decide to put buttons or other controls in that space

Just for clarity, child windows aren't put in the backbuffer. They're drawn to the client area.

 

EDIT: Now you've got me confused. The first rectangle in the Present parameter is set the same as the viewport rectangle. See the correction below.

 

Keep the backbuffer the size of the mainwindow's client area (the default) and set the viewport to the size of the rendering area desired (the size you want to appear in the client area.) For the Present call, set the first rectangle (source rect) to [0 <--EDIT: no] same rectangle as the viewport to present only the viewport area. Set the second rectangle parameter (destination rect) to the position and size in the client area where you want the scene to appear, e.g., the source rectangle with an offset relative to the client area.

 

Note: you can't use the DirectX presentation area in the client for anything else, but the rest of the client is yours to use.

 

client_area_text.png

 

EDIT2: If you want to use the entire backbuffer for rendering, you can also do that. Use the default viewport or set the viewport to the backbuffer size. Set the first Present parameter to 0 (present the entire backbuffer) and the second parameter as mentioned above. The entire backbuffer image will be resized (resampled, probably to your disliking) to the destination rectangle.


Edited by Buckeye, 23 February 2014 - 08:09 AM.

Please don't PM me with questions. Post them in the forums for everyone's benefit, and I can embarrass myself publicly.


#12 noatom   Members   -  Reputation: 782

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Posted 23 February 2014 - 09:05 AM

@Buckeye well thanks,however right now I made it work by just using a win32 control. For future readers: use the one you think it's easier(the one specified by Buckeye gives you more control over size and aspect ratio,but I guess you can resize win32 controls too so...your choice)






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