Direct2D: D2SwapChain...

[(X)]

I asked Bing: 

What does D2SwapChain do?  It seems to help with screen tearing.  Does it give us access to the screen as a bitmap.

Bing answered:

While D2DSwapChain does not directly give you access to D2DBitmap, you can create a D2DBitmap from the back buffer of the swap chain. This is typically done by using the CreateBitmapFromWicBitmap method. This allows you to draw onto the D2DBitmap and then present the updated image to the swap chain, which will then be displayed on the screen.

---

Here is a GFA provided demo...
'
' D2SwapChain
'
$Library "direct2d"

Global Object Win1RT, swapchain, d2ddev, d2dcontext, d2dbitmap
OpenW 1, 0, 0, 320, 360, ~15

Set Win1RT = D2GetRT(Me.hWnd) ' window RT
D2SwapChain Me.hWnd, swapchain, d2ddev, d2dcontext, d2dbitmap
Trace swapchain

Do
 Sleep
Until Me Is Nothing

Sub Win_1_Paint
 D2BeginDraw Win1RT, D2C_White
 D2ForeColor = D2C_Brown
 D2Box 20, 20, 120, 120
 D2DefLine , 0                 ' no outline
 D2PBox 20, 150, 120, 270
 
 ' Create and select a 50% transparent fillpattern
 D2DefLine                     ' restore default
 D2DefFill ARGB(128, 0, 128, 0)
 D2Box 70, 20, 240, 120
 D2DefLine , 0                 ' no outline
 D2PBox 70, 150, 240, 270
 
 D2EndDraw
EndSub

D2SwapChain and AutoRedraw=1 are both related to rendering graphics, but they serve different purposes.

D2SwapChain is a part of DirectX and is used for managing multiple buffers in graphics rendering. It’s primarily used in double buffering or triple buffering techniques, where the rendering is done off-screen and then swapped to the main screen once the rendering is complete. This helps in reducing screen tearing and stuttering in graphics-intensive applications like games.

On the other hand, AutoRedraw=1 is a property you might find in some graphics libraries or frameworks. When AutoRedraw is set to 1 (or true), it means that the screen will automatically be redrawn whenever a change is made to the graphical elements. This is useful in applications where the graphical elements change frequently and you want the screen to reflect these changes immediately.

So, while both D2SwapChain and AutoRedraw=1 deal with rendering graphics, they are used in different contexts and serve different purposes.

[Roger Cabo]

Interesting..

Does it give us access to the screen as a bitmap?
And how to access the bitmap? :-)

[(X)]

Jan 17, 2024 23:37:06 GMT 1 Roger Cabo said:

Interesting..

Does it give us access to the screen as a bitmap?
And how to access the bitmap? :-)

Bing answered:

While D2DSwapChain does not directly give you access to D2DBitmap...

1) You can create a D2DBitmap from the back buffer of the swap chain. 

This is typically done by using the CreateBitmapFromWicBitmap method.

2) This allows you to draw onto the D2DBitmap and then

3) present the updated image to the swap chain, which will then be displayed on the screen.

[Roger Cabo]

Hmm.. I didn't understand an advantage of this process..

D2SwapChain Me.hWnd, swapchain, d2ddev, d2dcontext, d2dbitmap
...

At first i thought I'm able to display the the back buffer anywhere at the screen
But it clears simply the screen.. anyway of x,y

D2Put 500,500 d2dbitmap

I wrote another example where


$Library "gfawinx"
$Library "UpdateRT"
$Library "direct2d"

// ........................................................................................................
// Calculate speed of passing a bitmap to D2D in real time (ouch!)
// ........................................................................................................

OpenW 1, 0, 0, _X, _Y, ~15

Global Object Win1RT
Set Win1RT = D2GetRT(Win_1.hWnd)
Set Me = Win_1

// ........................................................................................................
// Create a bitmap in the PC Ram
Type BITMAPINFOHEADER
 - DWord  biSize
 - Long   biWidth,         biHeight
 - Word   biPlanes,        biBitCount
 - DWord  biCompression,   biSizeImage
 - Long   biXPelsPerMeter, biYPelsPerMeter
 - DWord  biClrUsed,       biClrImportant
End Type

Type BITMAPINFO
 bmh As BITMAPINFOHEADER
End Type

Global bminfo As BITMAPINFO

bminfo.bmh.biSize = SizeOf(bminfo.bmh)
bminfo.bmh.biWidth = Win_1.Width / PixelsToTwipX(1)
bminfo.bmh.biHeight = Win_1.Height / PixelsToTwipY(1)
bminfo.bmh.biPlanes = 1
bminfo.bmh.biBitCount = 32
// ... biCompression, biSizeImage, biXPelsPerMeter, biYPelsPerMeter, biClrUsed, und biClrImportant = 0

Global RenderBmpRamAdr As Long

// ... Create a Bitmap in the PC Ram
Global RenderDib As Handle = CreateDIBSection(Null, bminfo, DIB_RGB_COLORS, V:RenderBmpRamAdr, Null, 0)

Global Object D2DRenderBMP

// ... ..................................... ....
// ... I didn't understand the how it's used ....
// ... ..................................... ....
Global Object swapchain, d2ddev, d2dcontext, d2dbitmap
D2SwapChain Me.hWnd, swapchain, d2ddev, d2dcontext, d2dbitmap

Global t# = Timer
Global counter%
Global frames#
FontSize = 18
Do
 D2BeginDraw Win1RT, D2C_Black
 RenderLoop()
 // D2EndDraw  // <---- Do not! Then you're able calculate performance and display by simple Print AT(,)
 PeekEvent
Until Me Is Nothing || MouseK

Proc RenderLoop()
 Static wait$ = "Wait!"
 Print AT(1, 1); wait$
 
 counter%++
 
 Dim td# = Timer
 // LByte (A|R|G|B)
 // 0.5ms at 4K
 MemZero RenderBmpRamAdr, bminfo.bmh.biWidth * bminfo.bmh.biHeight * 4 // fastest for clr the RenderBmpRamAdr memory.
 Dim mz# = Timer - td#
 
 // D2Bitmap takes about 6ms on my machine... that's quite a lot!
 // The bitmap must pass through the north bridge to the GPU... But the bandwidth through the north bridge is about 100GB/s... peanuts for the system.
 // Unfortunately, that takes too much time!!
 Set D2DRenderBMP = D2Bitmap(RenderDib, WICBitmapUsePremultipliedAlpha /* <--- fastest */)
 
 D2Put 0, 0, D2DRenderBMP
 td# = (Timer - td#) * 1000
 
 If Timer - t# => 1
   wait$ = ""
   t# = Timer
   // ~158 on UHD. ~260 on HD
   Print AT(1, 1); " Depends on the screen size!"
   Print  "------------------------------------------"
   Print  " MemZero RenderBmpRamAdr ms: " & mz#
   Print  " Loops per second : " & counter
   Print  " Set D2DRenderBMP = D2Bitmap() call ms " &  td#
   counter% = 0
 EndIf
EndProc


[(X)]

I wrote to our Help Doc editor about D2SwapChain...

Having explored the use of D2SwapChain in the Direct2D library, he found it more relevant to Direct3D.

D2SwapChain creates a sequence of images as back buffers for smooth animation or display. To function properly, it requires methods like Present and GetBuffer, and a way to repaint the object, which seems unachievable in GB32. The only method to add images to the back buffers in GB32 appears to be by loading bitmaps from other forms, which seems inefficient.

Given the current interest in 3D on the forum, the he suggests opening this issue to the community, hoping someone with a better understanding of 3D graphical interfaces could make this function practical.

I love a good puzzle and this one may indeed be a stumper.  We'll see how long this nut takes to crack!

[dragonjim]

For added information and functionality, here are two methods of the SwapChain object in the form of functions:

$Library "C:\Program Files (x86)\GFABASIC32\Include\UpdateRT.lg32"
$Library "C:\Program Files (x86)\GFABASIC32\Include\direct2d.lg32"
UpdateRuntime      ' Patches GfaWin23.Ocx

GUID IID_ID3D11Texture2D = 6f15aaf2-d208-4e89-9ab4-489535d34f9c
GUID IID_IDXGISwapChain1 = 790a45f7-0d42-4876-983a-0a55cfe6f4aa
Type IDXGISwapChain1Vtbl          ' inherits from IDXGISwapChain
 - Long QueryInterface, AddRef, Release
 - Long SetPrivateData, SetPrivateDataInterface, GetPrivateData, GetParent
 - Long GetDevice
 - Long Present, GetBuffer, SetFullscreenState, GetFullscreenState, GetDesc, _
   ResizeBuffers, ResizeTarget, GetContainingOutput, GetFrameStatistics, GetLastPresentCount
 ' Methods
 - Long GetDesc1, GetFullscreenDesc, GetHwnd, GetCoreWindow, Present1, IsTemporaryMonoSupported, _
   GetRestrictToOutput, SetBackgroundColor, GetBackgroundColor, SetRotation, GetRotation
EndType

Global Object Win1RT, swapchain, d2ddev, d2dcontext, d2dbitmap
OpenW 1, 0, 0, 320, 360, ~15
Set Win1RT = D2GetRT(Me.hWnd) ' window RT
D2SwapChain Me.hWnd, swapchain, d2ddev, d2dcontext, d2dbitmap

Function  D2SwapChain_Present(swapchain As Object, iSyncInterval As Int32, iFlags As Int32)
 /* Purpose: The IDXGISwapChain::Present method is used to display a rendered image to the user. It’s the point where your frame gets presented on the screen.
 /* Parameters:
 /* - iSyncInterval: An integer that specifies how to synchronize the presentation of a frame with the vertical blank. Depending on the swap effect model _
   (e.g., discard, sequential, or flip), different values are used. For example: _
   For the bit-block transfer (bitblt) model (used with DXGI_SWAP_EFFECT_DISCARD or DXGI_SWAP_EFFECT_SEQUENTIAL), _
   values range from 0 (immediate presentation) to 4 (synchronize after the nth vertical blank). _
   For the flip model (used with DXGI_SWAP_EFFECT_FLIP_SEQUENTIAL), _
   values range from 0 (cancel remaining time on the previously presented frame) to 4 (synchronize presentation for at least n vertical blanks).
 /* - iFlags: An integer value that contains swap-chain presentation options. These options are defined by the DXGI_PRESENT constants.
 /* Return Value : Possible return values include: _
   S_OK: Presentation succeeded. _
   DXGI_ERROR_DEVICE_RESET or DXGI_ERROR_DEVICE_REMOVED: Indicates issues related to the graphics device. _
   DXGI_STATUS_OCCLUDED: The window is partially or completely obscured. _
   D3DDDIERR_DEVICEREMOVED: The video card has been physically removed or had a driver upgrade.
 Local hr = StdCall({{{V:swapchain}} + OffsetOf(IDXGISwapChain1Vtbl.Present)})({V:swapchain}, iSyncInterval, iFlags)
 Assert hr <> 0 ' SwapChain_Present failed
EndFunction
Function  D2SwapChain_GetBackBuffer(swapchain As Object, iBackBuffer As Int32, Optional iType As Int32)
 /* Purpose: The GetBackBuffer method retrieves a back buffer from the device’s swap chain. Back buffers are essential for rendering and displaying frames.
 /* Parameters:
 /* - iBackBuffer: An index representing the back buffer object to return. Back buffers are numbered from 0 to the total number of back buffers minus one. _
   Note that a value of 0 corresponds to the first back buffer, not the front buffer. The front buffer is not accessible through this method.
 /* - Type: The type of back buffer requested. In Direct3D 9, stereo view is not supported, so the only valid value for this parameter is D3DBACKBUFFER_TYPE_MONO.
 /* Return Value : _
   If the method succeeds, the return value is D3D_OK. _
   If iBackBuffer exceeds the total number of back buffers, the function fails and returns D3DERR_INVALIDCALL.
 If iType = 0 Then iType = IID_ID3D11Texture2D
 Local backBuffer As Int32
 Local hr = StdCall({{{V:swapchain}} + OffsetOf(IDXGISwapChain1Vtbl.GetBuffer)})({V:swapchain}, iBackBuffer, iType, V:backBuffer)
 Assert hr <> 0 ' Failed to get Back Buffer handle
 Return backBuffer
EndFunction