Game Development Reference
In-Depth Information
What Is a Swap Chain?
An application utilizing Direct3D to render real-time 3D graphics organizes an
animated sequence into a series of frames that are stored in a collection of buffers,
and renders them in the correct sequence. These buffers are grouped into swap
chains that flip to the screen one after the other. A swap chain can render an
upcoming frame in the background and present the frame to the screen when
ready. This mechanism solves a common problem known as “tearing” and offers
smoother animation.
Every Direct3D device that is created automatically instantiates a single implicit
swap chain. When a surface flip is requested through the execution of
Device.Present , the pointers for the front and back buffer(s) are swapped, and a
new frame is presented to the viewer. If there is more than one back buffer in a
swap chain, the pointers are swapped in a circular order.
Additional swap chains can be created within a given device, though a device can
only contain a single full-screen swap chain. Each swap chain renders into a col-
lection of buffers and can be presented to a different window from the main device.
The back buffer for a swap chain can be accessed with SwapChain.GetBackBuffer .
NOTE
Before continuing, it is important to note that, by the term window, I am referring to any control.
This association goes back to the unmanaged Win32 API.
A great benefit of using swap chains with a single device is the notion that resources,
such as meshes and textures, are shared across all swap chains using a single loca-
tion in memory.
Creating a swap chain is very easy to do, and the only prerequisite is that a valid
Direct3D is already available. The first thing to do is to create a PresentParameters
object and specify some rendering properties about the swap chain. Most of the
properties are familiar from regular device settings, but the important ones to note
are DeviceWindow , BackBufferWidth , and BackBufferHeight . All three refer to the han-
dle, width, and height of the window (control) that the swap chain will be bound
to for rendering. The variable of this control is called renderTarget and is of type
System.Windows.Forms.Control .
The following code shows how to build present parameters for a swap chain.
PresentParameters presentParams = new PresentParameters();
presentParams.AutoDepthStencilFormat = DepthFormat.D16;
 
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