[D3D] swapchains and displaymodes

[chronozphere]

Hi everyone. :)

I have a few questions concerning Swapchains, because i want to implement them in my engine.

1. changing a swapchain's displaymode

Normally, when you want to change the displaymode in your game, You release your video-resources, call Device.Reset with new presentation parameters and restore your video-resources again. When using multiple swapchains, this isn't very efficient when you only need to change ONE swapchain.

So i thought it might be okay to release the swapchain you wish the displaymode to be changed, and recreate it with new presentation parameters. Is this a good way of doing this??

If so, is it possible to release all swapchains a device has, and recreate them with new presentation parameters, without having to free/restore other video resources?? This seems more efficient to me than the Device.reset method, also when you only have one swapchain. :)

2. swapchains v.s full-screen rendering

What happens when you create a fullscreen swapchain?? Of course, rendering to the other swapchains is ridiculous, but is this a valid action?? :?

And what about multiple full-screen swapchains?? :twisted:

thank you! ;)

[Clootie]

1. When you are creating D3dDevice - it automatically creates default swapchain. I'm not sure is it possible to have two swapchains for single monitor, when one of SC is fullscreen... Seems you have to try it by yourself.

2. The whole idea to have multiple swapchains is to enable easy way to present to two monitors [in fullscreen mode] which are connected to the same videocard (dual-head).

[chronozphere]

I just managed to make a swapchain test app. :)

It seems that it's impossible to create a fullscreen swapchain on one monitor.
CreateAdditionalSwapChain will fail. So question 2 is completely impossible.

Removing all swapchains cann't be done either because:

Device.GetSwapChain(0,SwapChain);
SwapChain := nil;

will simply not destroy the defaut swapchain, but only the reference to it.

I've been trying to make the backbuffer resize when the window is resized. No succes so far:


function MsgProc(hWnd: HWND; uMsg: UINT; wParam: WPARAM; lParam: LPARAM): LRESULT; stdcall;
var d3dpp: TD3DPresentParameters;
mode: TD3DDisplayMode;
begin
case uMsg of
WM_KEYDOWN:
begin
if wParam = VK_ESCAPE then
SendMessage(Hwnd,WM_CLOSE,0,0);
end;

WM_SIZE:
begin
//ACCES VIOLATION on the following line (at adress #00000000)
g_pD3D.GetAdapterDisplayMode(D3DADAPTER_DEFAULT,mo de);

// Set up the structure used to create the D3DDevice
FillChar(d3dpp, SizeOf(d3dpp), 0);
d3dpp.Windowed := true;
d3dpp.SwapEffect := D3DSWAPEFFECT_COPY;
d3dpp.BackBufferWidth := (lparam and $0000ffff);
d3dpp.BackBufferHeight := (lparam and $ffff0000 shr 16);
d3dpp.BackBufferFormat := mode.Format;

//if the first window is resized
if hwnd = hWindow then
begin
pSwap1 := nil;
g_pd3dDevice.CreateAdditionalSwapChain(d3dpp,pSwap 1);
end;
//if the second window is resized
if hwnd = hWindow2 then
begin
pSwap2 := nil;
g_pd3dDevice.CreateAdditionalSwapChain(d3dpp,pSwap 2);
end;
end;

WM_DESTROY:
begin
Cleanup;
PostQuitMessage(0);
Result:= 0;
Exit;
end;
end;

Result:= DefWindowProc(hWnd, uMsg, wParam, lParam);
end;


Does anyone know what i'm doing wrong?? Is g_pD3D out of scope or something. :?