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BackBuffers help

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The following code is straight out of the Tutorials - Vertices chapter in DirectX Documentation. This example just draws a single triangle and presents it in a window. I am very new to DirectX and wanted some help on BackBuffers. I want to expand this code so that multiple back buffers are created and I present them one at a time. I know how to create additional swap chains and associate them with back buffers. Where I need help is how to render/copy the triangle into these multiple back buffers?

//-----------------------------------------------------------------------------
// File: Vertices.cpp
//
// Desc: In this tutorial, we are rendering some vertices. This introduces the
//       concept of the vertex buffer, a Direct3D object used to store
//       vertices. Vertices can be defined any way we want by defining a
//       custom structure and a custom FVF (flexible vertex format). In this
//       tutorial, we are using vertices that are transformed (meaning they
//       are already in 2D window coordinates) and lit (meaning we are not
//       using Direct3D lighting, but are supplying our own colors).
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//-----------------------------------------------------------------------------
#include <d3d9.h>
#pragma warning( disable : 4996 ) // disable deprecated warning 
#include <strsafe.h>
#pragma warning( default : 4996 ) 




//-----------------------------------------------------------------------------
// Global variables
//-----------------------------------------------------------------------------
LPDIRECT3D9             g_pD3D       = NULL; // Used to create the D3DDevice
LPDIRECT3DDEVICE9       g_pd3dDevice = NULL; // Our rendering device
LPDIRECT3DVERTEXBUFFER9 g_pVB        = NULL; // Buffer to hold vertices

// A structure for our custom vertex type
struct CUSTOMVERTEX
{
    FLOAT x, y, z, rhw; // The transformed position for the vertex
    DWORD color;        // The vertex color
};

// Our custom FVF, which describes our custom vertex structure
#define D3DFVF_CUSTOMVERTEX (D3DFVF_XYZRHW|D3DFVF_DIFFUSE)




//-----------------------------------------------------------------------------
// Name: InitD3D()
// Desc: Initializes Direct3D
//-----------------------------------------------------------------------------
HRESULT InitD3D( HWND hWnd )
{
    // Create the D3D object.
    if( NULL == ( g_pD3D = Direct3DCreate9( D3D_SDK_VERSION ) ) )
        return E_FAIL;

    // Set up the structure used to create the D3DDevice
    D3DPRESENT_PARAMETERS d3dpp;
    ZeroMemory( &d3dpp, sizeof(d3dpp) );
    d3dpp.Windowed = TRUE;
    d3dpp.SwapEffect = D3DSWAPEFFECT_DISCARD;
    d3dpp.BackBufferFormat = D3DFMT_UNKNOWN;

    // Create the D3DDevice
    if( FAILED( g_pD3D->CreateDevice( D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, hWnd,
                                      D3DCREATE_SOFTWARE_VERTEXPROCESSING,
                                      &d3dpp, &g_pd3dDevice ) ) )
    {
        return E_FAIL;
    }

    // Device state would normally be set here

    return S_OK;
}




//-----------------------------------------------------------------------------
// Name: InitVB()
// Desc: Creates a vertex buffer and fills it with our vertices. The vertex
//       buffer is basically just a chuck of memory that holds vertices. After
//       creating it, we must Lock()/Unlock() it to fill it. For indices, D3D
//       also uses index buffers. The special thing about vertex and index
//       buffers is that they can be created in device memory, allowing some
//       cards to process them in hardware, resulting in a dramatic
//       performance gain.
//-----------------------------------------------------------------------------
HRESULT InitVB()
{
    // Initialize three vertices for rendering a triangle
    CUSTOMVERTEX vertices[] =
    {
        { 150.0f,  50.0f, 0.5f, 1.0f, 0xffff0000, }, // x, y, z, rhw, color
        { 250.0f, 250.0f, 0.5f, 1.0f, 0xff00ff00, },
        {  50.0f, 250.0f, 0.5f, 1.0f, 0xff00ffff, },
    };

    // Create the vertex buffer. Here we are allocating enough memory
    // (from the default pool) to hold all our 3 custom vertices. We also
    // specify the FVF, so the vertex buffer knows what data it contains.
    if( FAILED( g_pd3dDevice->CreateVertexBuffer( 3*sizeof(CUSTOMVERTEX),
                                                  0, D3DFVF_CUSTOMVERTEX,
                                                  D3DPOOL_DEFAULT, &g_pVB, NULL ) ) )
    {
        return E_FAIL;
    }

    // Now we fill the vertex buffer. To do this, we need to Lock() the VB to
    // gain access to the vertices. This mechanism is required becuase vertex
    // buffers may be in device memory.
    VOID* pVertices;
    if( FAILED( g_pVB->Lock( 0, sizeof(vertices), (void**)&pVertices, 0 ) ) )
        return E_FAIL;
    memcpy( pVertices, vertices, sizeof(vertices) );
    g_pVB->Unlock();

    return S_OK;
}




//-----------------------------------------------------------------------------
// Name: Cleanup()
// Desc: Releases all previously initialized objects
//-----------------------------------------------------------------------------
VOID Cleanup()
{
    if( g_pVB != NULL )        
        g_pVB->Release();

    if( g_pd3dDevice != NULL ) 
        g_pd3dDevice->Release();

    if( g_pD3D != NULL )       
        g_pD3D->Release();
}




//-----------------------------------------------------------------------------
// Name: Render()
// Desc: Draws the scene
//-----------------------------------------------------------------------------
VOID Render()
{
    // Clear the backbuffer to a blue color
    g_pd3dDevice->Clear( 0, NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB(0,0,255), 1.0f, 0 );

    // Begin the scene
    if( SUCCEEDED( g_pd3dDevice->BeginScene() ) )
    {
        // Draw the triangles in the vertex buffer. This is broken into a few
        // steps. We are passing the vertices down a "stream", so first we need
        // to specify the source of that stream, which is our vertex buffer. Then
        // we need to let D3D know what vertex shader to use. Full, custom vertex
        // shaders are an advanced topic, but in most cases the vertex shader is
        // just the FVF, so that D3D knows what type of vertices we are dealing
        // with. Finally, we call DrawPrimitive() which does the actual rendering
        // of our geometry (in this case, just one triangle).
        g_pd3dDevice->SetStreamSource( 0, g_pVB, 0, sizeof(CUSTOMVERTEX) );
        g_pd3dDevice->SetFVF( D3DFVF_CUSTOMVERTEX );
        g_pd3dDevice->DrawPrimitive( D3DPT_TRIANGLELIST, 0, 1 );

        // End the scene
        g_pd3dDevice->EndScene();
    }

    // Present the backbuffer contents to the display
    g_pd3dDevice->Present( NULL, NULL, NULL, NULL );
}




//-----------------------------------------------------------------------------
// Name: MsgProc()
// Desc: The window's message handler
//-----------------------------------------------------------------------------
LRESULT WINAPI MsgProc( HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam )
{
    switch( msg )
    {
        case WM_DESTROY:
            Cleanup();
            PostQuitMessage( 0 );
            return 0;
    }

    return DefWindowProc( hWnd, msg, wParam, lParam );
}




//-----------------------------------------------------------------------------
// Name: wWinMain()
// Desc: The application's entry point
//-----------------------------------------------------------------------------
INT WINAPI wWinMain( HINSTANCE hInst, HINSTANCE, LPWSTR, INT )
{
    // Register the window class
    WNDCLASSEX wc = { sizeof(WNDCLASSEX), CS_CLASSDC, MsgProc, 0L, 0L,
                      GetModuleHandle(NULL), NULL, NULL, NULL, NULL,
                      L"D3D Tutorial", NULL };
    RegisterClassEx( &wc );

    // Create the application's window
    HWND hWnd = CreateWindow( L"D3D Tutorial", L"D3D Tutorial 02: Vertices",
                              WS_OVERLAPPEDWINDOW, 100, 100, 300, 300,
                              NULL, NULL, wc.hInstance, NULL );

    // Initialize Direct3D
    if( SUCCEEDED( InitD3D( hWnd ) ) )
    {
        // Create the vertex buffer
        if( SUCCEEDED( InitVB() ) )
        {
            // Show the window
            ShowWindow( hWnd, SW_SHOWDEFAULT );
            UpdateWindow( hWnd );

            // Enter the message loop
            MSG msg;
            ZeroMemory( &msg, sizeof(msg) );
            while( msg.message!=WM_QUIT )
            {
                if( PeekMessage( &msg, NULL, 0U, 0U, PM_REMOVE ) )
                {
                    TranslateMessage( &msg );
                    DispatchMessage( &msg );
                }
                else
                    Render();
            }
        }
    }

    UnregisterClass( L"D3D Tutorial", wc.hInstance );
    return 0;
}

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Can you explain what exactly you want to do?

Normal rendering involved rendering frame after frame into the same back buffer. After each frame, the back buffer is swapped with the front, or copied into it. So drawing a series of images normally involves just one back buffer.

It's also possible to render to render targets, to not display the image as is, but do something with it.

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