高级纹理映射技术（5）

高级纹理映射技术（5）

Alpha混合操作

设置alpha操作的语句大致如下：

// i为纹理层序号
pd3dDevice->SetTextureStageState(i, D3DTSS_ALPHAARG1, arg1);
pd3dDevice->SetTextureStageState(i, D3DTSS_ALPHAARG2, arg2);
pd3dDevice->SetTextureStageState(i, D3DTSS_ALPHAOP, op);

参数op是属于枚举类型D3DTEXTUREOP的常量。和纹理颜色混合操作相同，纹理Alpha操作最多可接受三个颜色参数：D3DTSS_ALPHAARG0、D3DTSS_ALPHAARG1、D3DTSS_ALPHAARG2。

Direct3D在渲染一个场景时，它可以结合几种来源的颜色信息：顶点、当前材质、纹理贴图、先前写入渲染目标的颜色信息，然后将其中的一些颜色混合起来。同时也可以使用Alpha来指定Direct3D该以怎样的权重混合这些颜色，Alpha信息可以存储在顶点中、材质中、纹理贴图中。Alpha值为0表示完全透明，Alpha值为1表示不透明，其余0~1之间的值表示不同程度的透明。

如果要从一张纹理中获取Alpha值，应将D3DTA_TEXTURE作为Alpha参数。

如果要使用来自顶点中的Alpha值，应将D3DTA_DIFFUSE作为Alpha参数，并确保渲染状态D3DRS_DIFFUSEMATERIALSOURCE被设置为D3DMCS_COLOR1（这也是默认状态）。

如果要使用来自材质中的Alpha值，应将D3DTA_DIFFUSE作为Alpha参数，并确保渲染状态D3DRS_DIFFUSEMATERIALSOURCE被设置为D3DMCS_MATERIAL。

如果未用SetRenderState()设置D3DRS_DIFFUSEMATERIALSOURCE参数，则从默认来源（即顶点）获取漫反射颜色。

示例程序中将纹理颜色和Alpha混合的代码如下所示：

// set texture color and alpha blend method

pd3dDevice->SetTexture(0, g_texture);
pd3dDevice->SetTextureStageState(0, D3DTSS_TEXCOORDINDEX, 0);
pd3dDevice->SetTextureStageState(0, D3DTSS_COLORARG1, D3DTA_TEXTURE);
pd3dDevice->SetTextureStageState(0, D3DTSS_COLORARG2, D3DTA_DIFFUSE);
pd3dDevice->SetTextureStageState(0, D3DTSS_COLOROP, D3DTOP_MODULATE);

pd3dDevice->SetTextureStageState(0, D3DTSS_ALPHAARG1, D3DTA_TEXTURE);
pd3dDevice->SetTextureStageState(0, D3DTSS_ALPHAOP, D3DTOP_SELECTARG1);

pd3dDevice->SetRenderState(D3DRS_ALPHABLENDENABLE, TRUE);
pd3dDevice->SetRenderState(D3DRS_SRCBLEND, D3DBLEND_SRCALPHA);
pd3dDevice->SetRenderState(D3DRS_DESTBLEND, D3DBLEND_INVSRCALPHA);

Alpha操作从纹理中获取Alpha值，因为用到了Alpha混合，所以在上面的代码中还需要启用Alpha混合并设置Alpha混合系数。

 

运行效果：

 

主程序：

#include  " dxstdafx.h "
#include  " resource.h "

#pragma warning(disable :  4127   4995   4996 )

#define  release_com(p)    do { if(p) { (p)->Release(); (p) = NULL; } } while(0)

#define  IDC_TOGGLE_FULLSCREEN        1
#define  IDC_TOGGLE_REF                2
#define  IDC_CHANGE_DEVICE            3

struct  sCustomVertex
{
     float  x, y, z;
     float  u, v;
};

#define  D3DFVF_CUSTOM_VERTEX    (D3DFVF_XYZ | D3DFVF_TEX1)

const  D3DXCOLOR FONT_COLOR( 0.85f ,  0.85f ,  0.85f ,  1.0f );

CDXUTDialogResourceManager    g_dlg_resource_manager;
CD3DSettingsDlg                g_settings_dlg;
CDXUTDialog                    g_button_dlg;

IDirect3DVertexBuffer9 *         g_vertex_buffer;
IDirect3DTexture9 *             g_texture;

ID3DXFont *         g_font;
ID3DXSprite *     g_text_sprite;
bool             g_show_help  =   true ;

// --------------------------------------------------------------------------------------
//  Rejects any devices that aren't acceptable by returning false
// --------------------------------------------------------------------------------------
bool  CALLBACK IsDeviceAcceptable( D3DCAPS9 *  pCaps, D3DFORMAT AdapterFormat, 
                                  D3DFORMAT BackBufferFormat,  bool  bWindowed,  void *  pUserContext )
{
     //  Typically want to skip backbuffer formats that don't support alpha blending

    IDirect3D9 *  pD3D  =  DXUTGetD3DObject(); 

     if ( FAILED( pD3D -> CheckDeviceFormat( pCaps -> AdapterOrdinal, pCaps -> DeviceType, AdapterFormat, 
                    D3DUSAGE_QUERY_POSTPIXELSHADER_BLENDING, D3DRTYPE_TEXTURE, BackBufferFormat ) ) )
         return   false ;

     return   true ;
}


// --------------------------------------------------------------------------------------
//  Before a device is created, modify the device settings as needed.
// --------------------------------------------------------------------------------------
bool  CALLBACK ModifyDeviceSettings( DXUTDeviceSettings *  pDeviceSettings,  const  D3DCAPS9 *  pCaps,  void *  pUserContext )
{
     //  If video card does not support hardware vertex processing, then uses sofaware vertex processing.
     if ((pCaps -> DevCaps  &  D3DDEVCAPS_HWTRANSFORMANDLIGHT)  ==   0 )
        pDeviceSettings -> BehaviorFlags  =  D3DCREATE_SOFTWARE_VERTEXPROCESSING;

     static   bool  is_first_time  =   true ;

     if (is_first_time)
    {
        is_first_time  =   false ;

         //  if using reference device, then pop a warning message box.
         if (pDeviceSettings -> DeviceType  ==  D3DDEVTYPE_REF)
            DXUTDisplaySwitchingToREFWarning();
    }

     return   true ;
}


// --------------------------------------------------------------------------------------
//  Create any D3DPOOL_MANAGED resources here 
// --------------------------------------------------------------------------------------
HRESULT CALLBACK OnCreateDevice( IDirect3DDevice9 *  pd3dDevice, 
                                  const  D3DSURFACE_DESC *  pBackBufferSurfaceDesc, 
                                  void *  pUserContext )
{
    HRESULT    hr;

    V_RETURN(g_dlg_resource_manager.OnCreateDevice(pd3dDevice));
    V_RETURN(g_settings_dlg.OnCreateDevice(pd3dDevice));

    D3DXCreateFont(pd3dDevice,  18 ,  0 , FW_BOLD,  1 , FALSE, DEFAULT_CHARSET, OUT_DEFAULT_PRECIS, DEFAULT_QUALITY,
                   DEFAULT_PITCH  |  FF_DONTCARE, L " Arial " ,  & g_font);

    V_RETURN(D3DXCreateTextureFromFile(pd3dDevice, L " tree.tga " ,     & g_texture));
    
     //  create vertex buffer and fill data

    sCustomVertex vertices[]  =      
    {
        {  - 3.0f ,  - 3.0f ,   0.0f ,   0.0f ,  1.0f },
        {  - 3.0f ,   3.0f ,   0.0f ,   0.0f ,  0.0f },
        {   3.0f ,  - 3.0f ,   0.0f ,   1.0f ,  1.0f },
        {   3.0f ,   3.0f ,   0.0f ,   1.0f ,  0.0f }
    };

    pd3dDevice -> CreateVertexBuffer( sizeof (vertices),  0 , D3DFVF_CUSTOM_VERTEX, D3DPOOL_MANAGED,  & g_vertex_buffer, NULL);

     void *  ptr;
    g_vertex_buffer -> Lock( 0 ,  sizeof (vertices), ( void ** ) & ptr,  0 );
    memcpy(ptr, vertices,  sizeof (vertices));
    g_vertex_buffer -> Unlock();

     return  S_OK;
}


// --------------------------------------------------------------------------------------
//  Create any D3DPOOL_DEFAULT resources here 
// --------------------------------------------------------------------------------------
HRESULT CALLBACK OnResetDevice( IDirect3DDevice9 *  pd3dDevice, 
                                 const  D3DSURFACE_DESC *  pBackBufferSurfaceDesc, 
                                 void *  pUserContext )
{
    HRESULT hr;

    V_RETURN(g_dlg_resource_manager.OnResetDevice());
    V_RETURN(g_settings_dlg.OnResetDevice());
    V_RETURN(g_font -> OnResetDevice());
    V_RETURN(D3DXCreateSprite(pd3dDevice,  & g_text_sprite));

     //  set dialog position and size

    g_button_dlg.SetLocation(pBackBufferSurfaceDesc -> Width  -   170 ,  0 );
    g_button_dlg.SetSize( 170 ,  170 );

     //  setup world matrix
    D3DXMATRIX mat_world;
    D3DXMatrixIdentity( & mat_world);
    pd3dDevice -> SetTransform(D3DTS_WORLD,  & mat_world);

     //  setup view matrix

    D3DXMATRIX mat_view;
    D3DXVECTOR3 eye( 0.0f ,  0.0f ,  - 10.0f );
    D3DXVECTOR3  at( 0.0f ,  0.0f ,   0.0f );
    D3DXVECTOR3  up( 0.0f ,  1.0f ,   0.0f );

    D3DXMatrixLookAtLH( & mat_view,  & eye,  & at,  & up);
    pd3dDevice -> SetTransform(D3DTS_VIEW,  & mat_view);

     //  set projection matrix
    D3DXMATRIX mat_proj;
     float  aspect  =  ( float )pBackBufferSurfaceDesc -> Width  /  pBackBufferSurfaceDesc -> Height;
    D3DXMatrixPerspectiveFovLH( & mat_proj, D3DX_PI / 4 , aspect,  1.0f ,  100.0f );
    pd3dDevice -> SetTransform(D3DTS_PROJECTION,  & mat_proj);

     //  setup material

    D3DMATERIAL9 material;
    ZeroMemory( & material,  sizeof (D3DMATERIAL9));

    material.Ambient.r  =   1.0f ;
    material.Ambient.g  =   1.0f ;
    material.Ambient.b  =   1.0f ;
    material.Ambient.a  =   1.0f ;

    pd3dDevice -> SetMaterial( & material);

    pd3dDevice -> SetRenderState(D3DRS_AMBIENT,  0xFF00FF00 );

     //  set texture color and alpha blend method

    pd3dDevice -> SetTexture( 0 , g_texture);
    pd3dDevice -> SetTextureStageState( 0 , D3DTSS_TEXCOORDINDEX,     0 );
    pd3dDevice -> SetTextureStageState( 0 , D3DTSS_COLORARG1,        D3DTA_TEXTURE);
    pd3dDevice -> SetTextureStageState( 0 , D3DTSS_COLORARG2,        D3DTA_DIFFUSE);
    pd3dDevice -> SetTextureStageState( 0 , D3DTSS_COLOROP,            D3DTOP_MODULATE);

    pd3dDevice -> SetTextureStageState( 0 , D3DTSS_ALPHAARG1,        D3DTA_TEXTURE);
    pd3dDevice -> SetTextureStageState( 0 , D3DTSS_ALPHAOP,            D3DTOP_SELECTARG1);

    pd3dDevice -> SetRenderState(D3DRS_ALPHABLENDENABLE,    TRUE);
    pd3dDevice -> SetRenderState(D3DRS_SRCBLEND,            D3DBLEND_SRCALPHA);
    pd3dDevice -> SetRenderState(D3DRS_DESTBLEND,            D3DBLEND_INVSRCALPHA);

     return  S_OK;
}

// --------------------------------------------------------------------------------------
//  Release resources created in the OnResetDevice callback here 
// --------------------------------------------------------------------------------------
void  CALLBACK OnLostDevice(  void *  pUserContext )
{
    g_dlg_resource_manager.OnLostDevice();
    g_settings_dlg.OnLostDevice();
    g_font -> OnLostDevice();

    release_com(g_text_sprite);
}


// --------------------------------------------------------------------------------------
//  Release resources created in the OnCreateDevice callback here
// --------------------------------------------------------------------------------------
void  CALLBACK OnDestroyDevice(  void *  pUserContext )
{
    g_dlg_resource_manager.OnDestroyDevice();
    g_settings_dlg.OnDestroyDevice();    

    release_com(g_font);
    release_com(g_vertex_buffer);
    release_com(g_texture);
}

// --------------------------------------------------------------------------------------
//  Handle updates to the scene
// --------------------------------------------------------------------------------------
void  CALLBACK OnFrameMove( IDirect3DDevice9 *  pd3dDevice,  double  fTime,  float  fElapsedTime,  void *  pUserContext )
{
}

// --------------------------------------------------------------------------------------
//  Render the helper information
// --------------------------------------------------------------------------------------
void  RenderText()
{
    CDXUTTextHelper text_helper(g_font, g_text_sprite,  20 );
    
    text_helper.Begin();

     //  show frame and device states
    text_helper.SetInsertionPos( 5 ,  5 );
    text_helper.SetForegroundColor(FONT_COLOR);
    text_helper.DrawTextLine( DXUTGetFrameStats( true ) );
    text_helper.DrawTextLine( DXUTGetDeviceStats() );

     //  show other simple information
    text_helper.SetForegroundColor( D3DXCOLOR( 1.0f ,  1.0f ,  1.0f ,  1.0f ) );
    text_helper.DrawTextLine(L " Texture Alpha Blend " );

     //  show helper information
    
     const  D3DSURFACE_DESC *  surface_desc  =  DXUTGetBackBufferSurfaceDesc();

     if (g_show_help)
    {
        text_helper.SetInsertionPos( 10 , surface_desc -> Height  -   18   *   5 );
        text_helper.SetForegroundColor(FONT_COLOR);
        text_helper.DrawTextLine(L " Controls (F1 to hide): " );
        
        text_helper.SetInsertionPos( 40 , surface_desc -> Height  -   18   *   4 );
        text_helper.DrawTextLine(L " Quit: ESC " );
    }
     else
    {
        text_helper.SetInsertionPos( 10 , surface_desc -> Height  -   15   *   4 );
        text_helper.SetForegroundColor( D3DXCOLOR( 1.0f ,  1.0f ,  1.0f ,  1.0f ) );
        text_helper.DrawTextLine(L " Press F1 for help " );
    }

    text_helper.End();
}

// --------------------------------------------------------------------------------------
//  Render the scene 
// --------------------------------------------------------------------------------------
void  CALLBACK OnFrameRender( IDirect3DDevice9 *  pd3dDevice,  double  fTime,  float  fElapsedTime,  void *  pUserContext )
{
    HRESULT hr;

     if (g_settings_dlg.IsActive())
    {
        g_settings_dlg.OnRender(fElapsedTime);
         return ;
    }

     //  Clear the render target and the zbuffer 
    V( pd3dDevice -> Clear( 0 , NULL, D3DCLEAR_TARGET  |  D3DCLEAR_ZBUFFER, D3DCOLOR_ARGB( 0 ,  32 ,  64 ,  80 ),  1.0f ,  0 ) );

     //  Render the scene
     if ( SUCCEEDED( pd3dDevice -> BeginScene() ) )
    {
        pd3dDevice -> SetStreamSource( 0 , g_vertex_buffer,  0 ,  sizeof (sCustomVertex));
        pd3dDevice -> SetFVF(D3DFVF_CUSTOM_VERTEX);
        pd3dDevice -> DrawPrimitive(D3DPT_TRIANGLESTRIP,  0 ,  2 );

        RenderText();

        V(g_button_dlg.OnRender(fElapsedTime));

        V( pd3dDevice -> EndScene() );
    }
}


// --------------------------------------------------------------------------------------
//  Handle messages to the application 
// --------------------------------------------------------------------------------------
LRESULT CALLBACK MsgProc( HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam, 
                           bool *  pbNoFurtherProcessing,  void *  pUserContext )
{
     * pbNoFurtherProcessing  =  g_dlg_resource_manager.MsgProc(hWnd, uMsg, wParam, lParam);
     if ( * pbNoFurtherProcessing)
         return   0 ;

     if (g_settings_dlg.IsActive())
    {
        g_settings_dlg.MsgProc(hWnd, uMsg, wParam, lParam);
         return   0 ;
    }

     * pbNoFurtherProcessing  =  g_button_dlg.MsgProc(hWnd, uMsg, wParam, lParam);
     if ( * pbNoFurtherProcessing)
         return   0 ;

     return   0 ;
}


// --------------------------------------------------------------------------------------
//  Handle keybaord event
// --------------------------------------------------------------------------------------
void  CALLBACK OnKeyboardProc(UINT charater,  bool  is_key_down,  bool  is_alt_down,  void *  user_context)
{
     if (is_key_down)
    {
         switch (charater)
        {
         case  VK_F1:
            g_show_help  =   ! g_show_help;
             break ;
        }
    }
}

// --------------------------------------------------------------------------------------
//  Handle events for controls
// --------------------------------------------------------------------------------------
void  CALLBACK OnGUIEvent(UINT  event ,  int  control_id, CDXUTControl *  control,  void *  user_context)
{
     switch (control_id)
    {
     case  IDC_TOGGLE_FULLSCREEN:
        DXUTToggleFullScreen();
         break ;

     case  IDC_TOGGLE_REF:
        DXUTToggleREF();
         break ;

     case  IDC_CHANGE_DEVICE:
        g_settings_dlg.SetActive( true );
         break ;
    }
}

// --------------------------------------------------------------------------------------
//  Initialize dialogs
// --------------------------------------------------------------------------------------
void  InitDialogs()
{
    g_settings_dlg.Init( & g_dlg_resource_manager);
    g_button_dlg.Init( & g_dlg_resource_manager);

    g_button_dlg.SetCallback(OnGUIEvent);

     int  x  =   35 , y  =   10 , width  =   125 , height  =   22 ;

    g_button_dlg.AddButton(IDC_TOGGLE_FULLSCREEN, L " Toggle full screen " , x, y,         width, height);
    g_button_dlg.AddButton(IDC_TOGGLE_REF,          L " Toggle REF (F3) " ,     x, y  +=   24 , width, height);
    g_button_dlg.AddButton(IDC_CHANGE_DEVICE,      L " Change device (F2) " , x, y  +=   24 , width, height, VK_F2);    
}

// --------------------------------------------------------------------------------------
//  Initialize everything and go into a render loop
// --------------------------------------------------------------------------------------
INT WINAPI WinMain( HINSTANCE, HINSTANCE, LPSTR,  int  )
{
     //  Enable run-time memory check for debug builds.
#if  defined(DEBUG) | defined(_DEBUG)
    _CrtSetDbgFlag( _CRTDBG_ALLOC_MEM_DF  |  _CRTDBG_LEAK_CHECK_DF );
#endif

     //  Set the callback functions
    DXUTSetCallbackDeviceCreated( OnCreateDevice );
    DXUTSetCallbackDeviceReset( OnResetDevice );
    DXUTSetCallbackDeviceLost( OnLostDevice );
    DXUTSetCallbackDeviceDestroyed( OnDestroyDevice );
    DXUTSetCallbackMsgProc( MsgProc );
    DXUTSetCallbackFrameRender( OnFrameRender );
    DXUTSetCallbackFrameMove( OnFrameMove );
    DXUTSetCallbackKeyboard(OnKeyboardProc);
   
     //  TODO: Perform any application-level initialization here
    InitDialogs();

     //  Initialize DXUT and create the desired Win32 window and Direct3D device for the application
    DXUTInit(  true ,  true ,  true  );  //  Parse the command line, handle the default hotkeys, and show msgboxes
    DXUTSetCursorSettings(  true ,  true  );  //  Show the cursor and clip it when in full screen
    DXUTCreateWindow( L " Texture Color And Alpha Blend "  );
    DXUTCreateDevice( D3DADAPTER_DEFAULT,  true ,  640 ,  480 , IsDeviceAcceptable, ModifyDeviceSettings );

     //  Start the render loop
    DXUTMainLoop();

     //  TODO: Perform any application-level cleanup here

     return  DXUTGetExitCode();
}

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