DirectX3D画线接口ID3DXLine

   使用DrawPrimitive()绘制的线没法控制其线性和绘制虚线，为此DirectX3D提供了ID3DXLine接口用来绘制线。该接口中的

HRESULT Draw(
    CONST D3DXVECTOR2* pVertexList,
    DWORD dwVertexListCount,
    D3DCOLOR Color
    );

  方法中的pVertexList存放需要绘制顶点，他是以line strip的方式给出的，并且其中的点是屏幕坐标下的点。可以通过SetPattern()方法来控制绘制线的类型（虚线或者实线）。其他方法请参看MSDN中ID3DXLine的描述。

   

 

代码如下：

/********************************  
*  Author: rabbit729  
*  E-mail: [email protected]  
*  Date:   2011-07-04  
*  Description: D3DXLine使用
********************************/ 

#include <d3d9.h>
#include <d3dx9.h>

//-----------------------------------------------------------------------------
// 全局变量
//-----------------------------------------------------------------------------
LPDIRECT3D9             g_pD3D       = NULL; //Direct3D对象
LPDIRECT3DDEVICE9       g_pd3dDevice = NULL; //Direct3D设备对象
LPD3DXLINE              g_pLine      = NULL; //Direct3D线对象
D3DXVECTOR2*            g_pLineArr   = NULL; //线段顶点 

//-----------------------------------------------------------------------------
// Desc: 初始化Direct3D
//-----------------------------------------------------------------------------
HRESULT InitD3D( HWND hWnd )
{
	//创建Direct3D对象, 该对象用来创建Direct3D设备对象
    if( NULL == ( g_pD3D = Direct3DCreate9( D3D_SDK_VERSION ) ) )
        return E_FAIL;

	//设置D3DPRESENT_PARAMETERS结构, 准备创建Direct3D设备对象
    D3DPRESENT_PARAMETERS d3dpp; 
    ZeroMemory( &d3dpp, sizeof(d3dpp) );
    d3dpp.Windowed = TRUE;
    d3dpp.SwapEffect = D3DSWAPEFFECT_DISCARD;
    d3dpp.BackBufferFormat = D3DFMT_UNKNOWN;

	//创建Direct3D设备对象
    if( FAILED( g_pD3D->CreateDevice( D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, hWnd,
                                      D3DCREATE_SOFTWARE_VERTEXPROCESSING,
                                      &d3dpp, &g_pd3dDevice ) ) )
    {
        return E_FAIL;
    }

	// 创建Direct3D线对象
	if (FAILED(D3DXCreateLine(g_pd3dDevice, &g_pLine)))
	{
		return E_FAIL;
	}

	//填充线顶点,注意：线填充的都是屏幕坐标，不需要转换
	g_pLineArr = new D3DXVECTOR2[4];
	g_pLineArr[0].x = g_pLineArr[0].y = 50;
	g_pLineArr[1].x = 400;
	g_pLineArr[1].y = 50;
	g_pLineArr[2].x = 50;
	g_pLineArr[2].y = 400;
	g_pLineArr[3].x = 400;
	g_pLineArr[3].y = 400;

   return S_OK;
}


//-----------------------------------------------------------------------------
// Desc: 释放创建对象
//-----------------------------------------------------------------------------
VOID Cleanup()
{
	// 释放Line对象
	if (g_pLine != NULL)
	{
		g_pLine->Release();
	}
	//释放Direct3D设备对象
    if( g_pd3dDevice != NULL) 
        g_pd3dDevice->Release();

	//释放Direct3D对象
    if( g_pD3D != NULL)
        g_pD3D->Release();
}


//-----------------------------------------------------------------------------
// Desc: 渲染图形
//-----------------------------------------------------------------------------
VOID Render()
{
    //清空后台缓冲区
    g_pd3dDevice->Clear( 0, NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB(43, 43, 43), 1.0f, 0 );
    
    //开始在后台缓冲区绘制图形
    if( SUCCEEDED( g_pd3dDevice->BeginScene() ) )
    {
        //绘制线
		g_pLine->SetWidth(3.f);
		g_pLine->SetAntialias(TRUE);
		g_pLine->Draw(g_pLineArr, 4, 0xffffffff);
    
        //结束在后台缓冲区渲染图形
        g_pd3dDevice->EndScene();
    }

    //将在后台缓冲区绘制的图形提交到前台缓冲区显示
    g_pd3dDevice->Present( NULL, NULL, NULL, NULL );
}


//-----------------------------------------------------------------------------
// Desc: 消息处理
//-----------------------------------------------------------------------------
LRESULT WINAPI MsgProc( HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam )
{
    switch( msg )
    {
        case WM_DESTROY:
            Cleanup();
            PostQuitMessage( 0 );
            return 0;

        case WM_PAINT:
            Render();
            ValidateRect( hWnd, NULL );
            return 0;
    }

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


//-----------------------------------------------------------------------------
// Desc: 程序入口
//-----------------------------------------------------------------------------
INT WINAPI WinMain( HINSTANCE hInst, HINSTANCE, LPSTR, INT )
{
    //注册窗口类
    WNDCLASSEX wc = { sizeof(WNDCLASSEX), CS_CLASSDC, MsgProc, 0L, 0L, 
                      GetModuleHandle(NULL), NULL, NULL, NULL, NULL,
                      L"ClassName", NULL };
    RegisterClassEx( &wc );

    //创建窗口
    HWND hWnd = CreateWindow( L"ClassName", L"Direct Line使用", 
                              WS_OVERLAPPEDWINDOW, 200, 100, 600, 500,
                              NULL, NULL, wc.hInstance, NULL );

    //初始化Direct3D
    if( SUCCEEDED( InitD3D( hWnd ) ) )
    { 
        //显示主窗口
		ShowWindow( hWnd, SW_SHOWDEFAULT );
		UpdateWindow( hWnd );

		//进入消息循环
		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();  //渲染图形
			}
		}
    }

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