alphablend.cpp

一本书上的例子

//=============================================================================
// Desc: Alpha混合测试
//=============================================================================

#include <d3dx9.h>


//-----------------------------------------------------------------------------
// Desc: 全局变量
//-----------------------------------------------------------------------------
LPDIRECT3D9             g_pD3D           = NULL; //Direct3D对象
LPDIRECT3DDEVICE9       g_pd3dDevice     = NULL; //Direct3D设备对象
LPD3DXMESH              g_pMesh          = NULL; //网格模型对象
D3DMATERIAL9*           g_pMeshMaterials = NULL; //网格模型材质
LPDIRECT3DTEXTURE9*     g_pMeshTextures  = NULL; //网格模型纹理
DWORD                   g_dwNumMaterials = 0L;   //网格模型子块数量


//-----------------------------------------------------------------------------
// Desc: 设置世界矩阵
//-----------------------------------------------------------------------------
VOID SetWorldMatrix()
{
    //创建并设置世界矩阵
    D3DXMATRIXA16 matWorld;
    D3DXMatrixRotationY( &matWorld, timeGetTime()/1000.0f );
    g_pd3dDevice->SetTransform( D3DTS_WORLD, &matWorld );
}

//-----------------------------------------------------------------------------
// Desc: 设置观察矩阵和投影矩阵
//-----------------------------------------------------------------------------
VOID SetViewAndProjMatrix()
{
    //创建并设置观察矩阵
    D3DXVECTOR3 vEyePt( 0.0f, 15.0f, -20.0f );
    D3DXVECTOR3 vLookatPt( 0.0f, 0.0f, 0.0f );
    D3DXVECTOR3 vUpVec( 0.0f, 1.0f, 0.0f );
    D3DXMATRIXA16 matView;
    D3DXMatrixLookAtLH( &matView, &vEyePt, &vLookatPt, &vUpVec );
    g_pd3dDevice->SetTransform( D3DTS_VIEW, &matView );

    //创建并设置投影矩阵
    D3DXMATRIXA16 matProj;
    D3DXMatrixPerspectiveFovLH( &matProj, D3DX_PI/4, 1.0f, 1.0f, 100.0f );
    g_pd3dDevice->SetTransform( D3DTS_PROJECTION, &matProj );
}


//-----------------------------------------------------------------------------
// Desc: 初始化Direct3D
//-----------------------------------------------------------------------------
HRESULT InitD3D( HWND hWnd )
{
    //创建Direct3D对象, 该对象用于创建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;
    d3dpp.EnableAutoDepthStencil = TRUE;
    d3dpp.AutoDepthStencilFormat = D3DFMT_D16;

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

	//Alpha混合设置, 设置混合系数
	g_pd3dDevice->SetRenderState( D3DRS_ALPHABLENDENABLE,   true );
	g_pd3dDevice->SetRenderState( D3DRS_SRCBLEND,  D3DBLEND_SRCALPHA );
	g_pd3dDevice->SetRenderState( D3DRS_DESTBLEND, D3DBLEND_INVSRCALPHA );

    //深度测试相关设置
    g_pd3dDevice->SetRenderState( D3DRS_ZENABLE, true );
	g_pd3dDevice->SetRenderState( D3DRS_ZFUNC, D3DCMP_LESS );
	g_pd3dDevice->SetRenderState( D3DRS_ZWRITEENABLE, TRUE );

    //设置环境光
    g_pd3dDevice->SetRenderState( D3DRS_AMBIENT, 0xffffffff );

	//设置观察矩阵和投影矩阵
	SetViewAndProjMatrix();

    return S_OK;
}


//-----------------------------------------------------------------------------
// Desc: 从绝对路径中提取纹理文件名
//-----------------------------------------------------------------------------
void RemovePathFromFileName(LPSTR fullPath, LPWSTR fileName)
{
	//先将fullPath的类型变换为LPWSTR
	WCHAR wszBuf[MAX_PATH];
	MultiByteToWideChar( CP_ACP, 0, fullPath, -1, wszBuf, MAX_PATH );
	wszBuf[MAX_PATH-1] = L'\0';

	WCHAR* wszFullPath = wszBuf;

	//从绝对路径中提取文件名
	LPWSTR pch=wcsrchr(wszFullPath,'\\');
	if (pch)
		lstrcpy(fileName, ++pch);
	else
		lstrcpy(fileName, wszFullPath);
}


//-----------------------------------------------------------------------------
// Desc: 创建场景图形
//-----------------------------------------------------------------------------
HRESULT InitGeometry()
{
    LPD3DXBUFFER pD3DXMtrlBuffer;

    //加载文件模型
    if( FAILED( D3DXLoadMeshFromX( L"Heli.x", D3DXMESH_SYSTEMMEM, 
                                   g_pd3dDevice, NULL, 
                                   &pD3DXMtrlBuffer, NULL, &g_dwNumMaterials, 
                                   &g_pMesh ) ) )
    {
		return E_FAIL;
	}

    //提取材质和纹理数据
    D3DXMATERIAL* d3dxMaterials = (D3DXMATERIAL*)pD3DXMtrlBuffer->GetBufferPointer();
    g_pMeshMaterials = new D3DMATERIAL9[g_dwNumMaterials];
    g_pMeshTextures  = new LPDIRECT3DTEXTURE9[g_dwNumMaterials];

    for( DWORD i=0; i<g_dwNumMaterials; i++ )
    {
        g_pMeshMaterials[i] = d3dxMaterials[i].MatD3D;
        g_pMeshMaterials[i].Ambient = g_pMeshMaterials[i].Diffuse;

        g_pMeshTextures[i] = NULL;
        if( d3dxMaterials[i].pTextureFilename != NULL && 
            strlen(d3dxMaterials[i].pTextureFilename) > 0 )
        {
			//获取纹理文件名
			WCHAR filename[256];
			RemovePathFromFileName(d3dxMaterials[i].pTextureFilename, filename);

            //创建纹理对象
            if( FAILED( D3DXCreateTextureFromFile( g_pd3dDevice, filename, 
                                                   &g_pMeshTextures[i] ) ) )
            {
				return E_FAIL;
            }
        }
    }

    //释放保存模型材质和纹理数据的数据对象
    pD3DXMtrlBuffer->Release();

    return S_OK;
}


//-----------------------------------------------------------------------------
// Desc: 释放创建的对象
//-----------------------------------------------------------------------------
VOID Cleanup()
{
	//释放网格模型材质
    if( g_pMeshMaterials != NULL ) 
        delete[] g_pMeshMaterials;

	//释放网格模型纹理
    if( g_pMeshTextures )
    {
        for( DWORD i = 0; i < g_dwNumMaterials; i++ )
        {
            if( g_pMeshTextures[i] )
                g_pMeshTextures[i]->Release();
        }
        delete[] g_pMeshTextures;
    }

	//释放网格模型对象
    if( g_pMesh != NULL )
        g_pMesh->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()
{
    //清除后缓冲区和深度缓冲区
    g_pd3dDevice->Clear( 0, NULL, D3DCLEAR_TARGET|D3DCLEAR_ZBUFFER, 
                         D3DCOLOR_XRGB(0,0,255), 1.0f, 0 );
    
    //开始在后台缓冲区绘制图形
    if( SUCCEEDED( g_pd3dDevice->BeginScene() ) )
    {
        SetWorldMatrix();   //设置世界矩阵

		//绘制不透明部分, 必须先绘制不透明的物体
        for( DWORD i=0; i<g_dwNumMaterials; i++ )
        {
			if(g_pMeshMaterials[i].Diffuse.a==1.0f)
			{
				g_pd3dDevice->SetMaterial( &g_pMeshMaterials[i] );
				g_pd3dDevice->SetTexture( 0, g_pMeshTextures[i] );
				g_pMesh->DrawSubset( i );
			}
        }

		//绘制透明部分
        for( DWORD i=0; i<g_dwNumMaterials; i++ )
        {
			if(g_pMeshMaterials[i].Diffuse.a!=1.f)
			{
				g_pd3dDevice->SetMaterial( &g_pMeshMaterials[i] );
				g_pd3dDevice->SetTexture( 0, g_pMeshTextures[i] );
				g_pMesh->DrawSubset( i );
			}
        }

		//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_KEYDOWN:
		switch(wParam)
		{
		case 48:  //"0"键, 禁用Alpha混合
			g_pd3dDevice->SetRenderState(D3DRS_ALPHABLENDENABLE, false);
			break;

		case 49: //"1"键, 激活Alpha混合
			g_pd3dDevice->SetRenderState(D3DRS_ALPHABLENDENABLE, true);
			break;
		}
		return 0;
    }

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


//-----------------------------------------------------------------------------
// Desc: 入口函数
//-----------------------------------------------------------------------------
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"Alpha混合", 
                              WS_OVERLAPPEDWINDOW, 200, 100, 500, 500,
                              GetDesktopWindow(), NULL, wc.hInstance, NULL );

	//初始化Direct3D
    if( SUCCEEDED( InitD3D( hWnd ) ) )
    {
		//创建场景图形
        if( SUCCEEDED( InitGeometry() ) )
        {
            //显示窗口
            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();
            }
        }
    }

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