ALPHA混合示例

技巧如下:

设置可变顶点格式时增加一个D3DCOLOR类型的漫反射分量,其中的alpha值指定了alpha混合因子。

// The 2D vertex format and descriptor
typedef struct
{
    
float x, y, z;      // 2D coordinates
    float rhw;          // rhw
    D3DCOLOR diffuse;   // diffuse color component
} VERTEX;

#define VERTEX_FVF   (D3DFVF_XYZRHW | D3DFVF_DIFFUSE)

// initialize vertex data
    VERTEX verts[] = {
      { 
100.0f100.0f1.0f1.0f, D3DCOLOR_RGBA(0,64,128,255) },
      { 
300.0f100.0f1.0f1.0f, D3DCOLOR_RGBA(0,64,128,255) },
      { 
100.0f300.0f1.0f1.0f, D3DCOLOR_RGBA(0,64,128,255) },
      { 
300.0f300.0f1.0f1.0f, D3DCOLOR_RGBA(0,64,128,255) },
      {  
50.0f150.0f1.0f1.0f, D3DCOLOR_RGBA(128,0,0,128)  },
      { 
350.0f150.0f1.0f1.0f, D3DCOLOR_RGBA(128,0,0,128)  },
      {  
50.0f350.0f1.0f1.0f, D3DCOLOR_RGBA(128,0,0,128)  },
      { 
350.0f350.0f1.0f1.0f, D3DCOLOR_RGBA(128,0,0,128)  }
    };

D3DCOLOR类型可以用D3DCOLOR_RGBA宏来生成,定义如下:

// maps unsigned 8 bits/channel to D3DCOLOR
#define D3DCOLOR_ARGB(a,r,g,b) \
    ((D3DCOLOR)((((a)
&0xff)<<24)|(((r)&0xff)<<16)|(((g)&0xff)<<8)|((b)&0xff)))

#define D3DCOLOR_RGBA(r,g,b,a) D3DCOLOR_ARGB(a,r,g,b)

其中的a指定了alpha因子,a为255表示该颜色完全不透明,a为0表示该颜色完全透明。

在绘制的时候,将首先绘制的图形设置为禁用alpha混合模式,将后面绘制的图形设置为启用alpha混合模式,并设置alpha混合具体模式。

       // disable alpha blending and draw 2 polygons
        g_d3d_device->SetRenderState(D3DRS_ALPHABLENDENABLE, FALSE);
        g_d3d_device
->DrawPrimitive(D3DPT_TRIANGLESTRIP, 02);

        
// enable alpha blending and draw 2 polygons
        g_d3d_device->SetRenderState(D3DRS_ALPHABLENDENABLE, TRUE);
        g_d3d_device
->SetRenderState(D3DRS_SRCBLEND, D3DBLEND_SRCALPHA);
        g_d3d_device
->SetRenderState(D3DRS_DESTBLEND, D3DBLEND_INVSRCALPHA);
        g_d3d_device
->DrawPrimitive(D3DPT_TRIANGLESTRIP, 42);   

完整源码如下:

/***************************************************************************************
PURPOSE:
    Alpha blending Demo

Required libraries:
  D3D9.LIB
 **************************************************************************************
*/

#include 
<windows.h>
#include 
<stdio.h>
#include 
"d3d9.h"

#pragma comment(lib, 
"d3d9.lib")

#define WINDOW_WIDTH    400
#define WINDOW_HEIGHT   400

#define Safe_Release(p) if((p)) (p)->Release();

// window handles, class and caption text.
HWND        g_hwnd;
HINSTANCE   g_inst;
static char g_class_name[] = "AlphaClass";
static char g_caption[]    = "Alpha Blending Demo";

// the Direct3D and device object
IDirect3D9* g_d3d = NULL;
IDirect3DDevice9
* g_d3d_device = NULL;

// The 2D vertex format and descriptor
typedef struct
{
    
float x, y, z;      // 2D coordinates
    float rhw;          // rhw
    D3DCOLOR diffuse;   // diffuse color component
} VERTEX;

#define VERTEX_FVF   (D3DFVF_XYZRHW | D3DFVF_DIFFUSE)

IDirect3DVertexBuffer9
* g_vertex_buffer = NULL;
IDirect3DTexture9
*      g_texture = NULL;

//--------------------------------------------------------------------------------
// Window procedure.
//--------------------------------------------------------------------------------
long WINAPI Window_Proc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    
switch(msg)
    {
    
case WM_DESTROY:
        PostQuitMessage(
0);
        
return 0;
    }

    
return (long) DefWindowProc(hwnd, msg, wParam, lParam);
}

//--------------------------------------------------------------------------------
// Initialize d3d, d3d device, vertex buffer, texutre. 
//--------------------------------------------------------------------------------
BOOL Do_Init()
{
    D3DPRESENT_PARAMETERS present_param;
    D3DDISPLAYMODE  display_mode;
    BYTE
* vertex_ptr;

    
// initialize vertex data
    VERTEX verts[] = {
      { 
100.0f100.0f1.0f1.0f, D3DCOLOR_RGBA(0,64,128,255) },
      { 
300.0f100.0f1.0f1.0f, D3DCOLOR_RGBA(0,64,128,255) },
      { 
100.0f300.0f1.0f1.0f, D3DCOLOR_RGBA(0,64,128,255) },
      { 
300.0f300.0f1.0f1.0f, D3DCOLOR_RGBA(0,64,128,255) },
      {  
50.0f150.0f1.0f1.0f, D3DCOLOR_RGBA(128,0,0,128)  },
      { 
350.0f150.0f1.0f1.0f, D3DCOLOR_RGBA(128,0,0,128)  },
      {  
50.0f350.0f1.0f1.0f, D3DCOLOR_RGBA(128,0,0,128)  },
      { 
350.0f350.0f1.0f1.0f, D3DCOLOR_RGBA(128,0,0,128)  }
    }; 

    
// do a windowed mode initialization of Direct3D
    if((g_d3d = Direct3DCreate9(D3D_SDK_VERSION)) == NULL)
        
return FALSE;

    
// retrieves the current display mode of the adapter
    if(FAILED(g_d3d->GetAdapterDisplayMode(D3DADAPTER_DEFAULT, &display_mode)))
        
return FALSE;

    ZeroMemory(
&present_param, sizeof(present_param));

    
// initialize d3d presentation parameter
    present_param.Windowed          = TRUE;
    present_param.SwapEffect        
= D3DSWAPEFFECT_DISCARD;
    present_param.BackBufferFormat  
= display_mode.Format;

    
// creates a device to represent the display adapter
    if(FAILED(g_d3d->CreateDevice(D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, g_hwnd,
                                  D3DCREATE_SOFTWARE_VERTEXPROCESSING, 
&present_param, &g_d3d_device)))
        
return FALSE;     

    
// create the vertex buffer and set data
    g_d3d_device->CreateVertexBuffer(sizeof(VERTEX) * 80, VERTEX_FVF, D3DPOOL_DEFAULT, &g_vertex_buffer, NULL);

    
// locks a range of vertex data and obtains a pointer to the vertex buffer memory
    g_vertex_buffer->Lock(00, (void**)&vertex_ptr, 0);

    memcpy(vertex_ptr, verts, 
sizeof(verts));

    
// unlocks vertex data
    g_vertex_buffer->Unlock();

    
return TRUE;
}

//--------------------------------------------------------------------------------
// Release all d3d resource.
//--------------------------------------------------------------------------------
BOOL Do_Shutdown()
{
    Safe_Release(g_vertex_buffer);
    Safe_Release(g_d3d_device);
    Safe_Release(g_d3d);

    
return TRUE;
}

//--------------------------------------------------------------------------------
// Render a frame.
//--------------------------------------------------------------------------------
BOOL Do_Frame()
{
    
// clear device back buffer
    g_d3d_device->Clear(0, NULL, D3DCLEAR_TARGET, D3DCOLOR_RGBA(000255), 1.0f0);

    
// Begin scene
    if(SUCCEEDED(g_d3d_device->BeginScene()))
    {
        
// set the vertex stream, shader, and texture.

        
// binds a vertex buffer to a device data stream
        g_d3d_device->SetStreamSource(0, g_vertex_buffer, 0sizeof(VERTEX));

        
// set the current vertex stream declation
        g_d3d_device->SetFVF(VERTEX_FVF);

        
// assigns a texture to a stage for a device
        g_d3d_device->SetTexture(0, g_texture);

        
// disable alpha blending and draw 2 polygons
        g_d3d_device->SetRenderState(D3DRS_ALPHABLENDENABLE, FALSE);
        g_d3d_device
->DrawPrimitive(D3DPT_TRIANGLESTRIP, 02);

        
// enable alpha blending and draw 2 polygons
        g_d3d_device->SetRenderState(D3DRS_ALPHABLENDENABLE, TRUE);
        g_d3d_device
->SetRenderState(D3DRS_SRCBLEND, D3DBLEND_SRCALPHA);
        g_d3d_device
->SetRenderState(D3DRS_DESTBLEND, D3DBLEND_INVSRCALPHA);
        g_d3d_device
->DrawPrimitive(D3DPT_TRIANGLESTRIP, 42);        

        
// end the scene
        g_d3d_device->EndScene();
    }

    
// present the contents of the next buffer in the sequence of back buffers owned by the device
    g_d3d_device->Present(NULL, NULL, NULL, NULL);

    
return TRUE;
}

//--------------------------------------------------------------------------------
// Main function, routine entry.
//--------------------------------------------------------------------------------
int WINAPI WinMain(HINSTANCE inst, HINSTANCE, LPSTR cmd_line, int cmd_show)
{
    WNDCLASSEX  win_class;
    MSG         msg;

    g_inst 
= inst;

    
// create window class and register it
    win_class.cbSize        = sizeof(win_class);
    win_class.style         
= CS_CLASSDC;
    win_class.lpfnWndProc   
= Window_Proc;
    win_class.cbClsExtra    
= 0;
    win_class.cbWndExtra    
= 0;
    win_class.hInstance     
= inst;
    win_class.hIcon         
= LoadIcon(NULL, IDI_APPLICATION);
    win_class.hCursor       
= LoadCursor(NULL, IDC_ARROW);
    win_class.hbrBackground 
= NULL;
    win_class.lpszMenuName  
= NULL;
    win_class.lpszClassName 
= g_class_name;
    win_class.hIconSm       
= LoadIcon(NULL, IDI_APPLICATION);

    
if(! RegisterClassEx(&win_class))
        
return FALSE;

    
// create the main window
    g_hwnd = CreateWindow(g_class_name, g_caption, WS_CAPTION | WS_SYSMENU, 00,
                          WINDOW_WIDTH, WINDOW_HEIGHT, NULL, NULL, inst, NULL);

    
if(g_hwnd == NULL)
        
return FALSE;

    ShowWindow(g_hwnd, SW_NORMAL);
    UpdateWindow(g_hwnd);

    
// initialize game
    if(Do_Init() == FALSE)
        
return FALSE;

    
// start message pump, waiting for signal to quit.
    ZeroMemory(&msg, sizeof(MSG));

    
while(msg.message != WM_QUIT)
    {
        
if(PeekMessage(&msg, NULL, 00, PM_REMOVE))
        {
            TranslateMessage(
&msg);
            DispatchMessage(
&msg);
        }
        
        
// draw a frame
        if(Do_Frame() == FALSE)
            
break;
    }

    
// run shutdown function
    Do_Shutdown();

    UnregisterClass(g_class_name, inst);
    
    
return (int) msg.wParam;
}

效果图:


posted @ 2007-08-27 17:30  至尊王者  阅读(872)  评论(0编辑  收藏  举报