创建游戏内核（11）

本篇是创建游戏内核（10）的续篇，其中涉及到的顶点缓存知识请参阅D3D中基本立体面的绘制。

顶点和VERTEX_BUFFER

顶点是一个麻烦的东西，有时对它束手无策，通过提供一种快速创建、设置以及渲染顶点集合的方法，VERTEX_BUFFER类能够减少此烦恼。

来看看VERTEX_BUFFER类的定义：

class VERTEX_BUFFER
{
private:
    GRAPHICS*               _graphics;      // pointer to graphics object
    IDirect3DVertexBuffer9* _vertex_buffer; // pointer to Direct3D vertex buffer object

    DWORD                   _num_vertices;  // number of vertex
    DWORD                   _vertex_size;   // vertex size
    DWORD                   _fvf;           // flexible vertex format

    BOOL                    _is_locked;     // flag indicates if vertex buffer has been locked
    char*                   _ptr;           // pointer to vertex data buffer

public:
    VERTEX_BUFFER();
    ~VERTEX_BUFFER();

    IDirect3DVertexBuffer9* Get_Vertex_buffer_COM();

    unsigned long Get_Vertex_Size();
    unsigned long Get_Vertex_FVF();
    unsigned long Get_Num_Vertices();

    BOOL Create(GRAPHICS* graphics, unsigned long num_vertices, unsigned long vertex_size, DWORD fvf);
    void Free();

    BOOL Is_Loaded();

    BOOL Set(unsigned long first_vertex, unsigned long num_vertices, void* vertex_list);
    BOOL Render(unsigned long first_vertex, unsigned long num_primitives, DWORD type);

    BOOL Lock(unsigned long first_vertex = 0, unsigned long num_vertices = 0);
    BOOL Unlock();
    void* Get_Ptr();
};

接着是类VERTEX_BUFFER的实现：

//---------------------------------------------------------------------------
// Constructor, initialize data member.
//---------------------------------------------------------------------------
VERTEX_BUFFER::VERTEX_BUFFER()
{
    _graphics       = NULL;
    _vertex_buffer  = NULL;
    _ptr            = NULL;

    _num_vertices   = 0;
    _fvf            = 0;

    _is_locked      = FALSE;
}

//---------------------------------------------------------------------------
// Destructor, free vertex buffer resource.
//---------------------------------------------------------------------------
VERTEX_BUFFER::~VERTEX_BUFFER()
{
    Free();
}

//---------------------------------------------------------------------------
// Get pointer to vetex buffer.
//---------------------------------------------------------------------------
IDirect3DVertexBuffer9* VERTEX_BUFFER::Get_Vertex_buffer_COM()
{
    return _vertex_buffer;
}

//---------------------------------------------------------------------------
// Gets the size of a vertex for a flexible vertex format (FVF)
//---------------------------------------------------------------------------
unsigned long VERTEX_BUFFER::Get_Vertex_Size()
{
    return D3DXGetFVFVertexSize(_fvf);
}

//---------------------------------------------------------------------------
// Get flexible vertex format.
//---------------------------------------------------------------------------
unsigned long VERTEX_BUFFER::Get_Vertex_FVF()
{
    return _fvf;
}

//---------------------------------------------------------------------------
// Get number of vertex.
//---------------------------------------------------------------------------
unsigned long VERTEX_BUFFER::Get_Num_Vertices()
{
    return _num_vertices;
}

//---------------------------------------------------------------------------
// Create vertex buffer.
//---------------------------------------------------------------------------
BOOL VERTEX_BUFFER::Create(GRAPHICS* graphics, unsigned long num_vertices, unsigned long vertex_size, DWORD fvf)
{
    // free vertex buffer resource first
    Free();

    // Check condition

    if((_graphics = graphics) == NULL)
        return FALSE;

    if(_graphics->Get_Device_COM() == NULL)
        return FALSE;

    if(!(_num_vertices = num_vertices) || !(_fvf = fvf) || !(_vertex_size = vertex_size))
        return FALSE;

    // create vertex buffer now
    if(FAILED(_graphics->Get_Device_COM()->CreateVertexBuffer(
        _num_vertices * _vertex_size, 0, _fvf, D3DPOOL_MANAGED, &_vertex_buffer, NULL)))
        return FALSE;

    return TRUE;
}

//---------------------------------------------------------------------------
// Free vertex buffer resource, reset data member.
//---------------------------------------------------------------------------
void VERTEX_BUFFER::Free()
{
    Unlock();

    Release_COM(_vertex_buffer);

    _graphics = NULL;
    _ptr      = NULL;

    _num_vertices = 0;
    _fvf          = 0;

    _is_locked = FALSE;
}

//---------------------------------------------------------------------------
// Copy vertex data from VertexList to vertex buffer.
//---------------------------------------------------------------------------
BOOL VERTEX_BUFFER::Set(unsigned long first_vertex, unsigned long num_vertices, void* vertex_list)
{
    // check condition

    if(_graphics == NULL || vertex_list == NULL || _vertex_buffer == NULL)
        return FALSE;

    if(_graphics->Get_Device_COM() == NULL)
        return FALSE;

    // lock the vertex buffer
    if(! Lock(first_vertex, num_vertices))
        return FALSE;

    // copy vertices to vertex buffer
    memcpy(_ptr, vertex_list, num_vertices * _vertex_size);

    // unlock vertex buffer
    return Unlock();
}

//---------------------------------------------------------------------------
// Render vertex buffer into display.
//---------------------------------------------------------------------------
BOOL VERTEX_BUFFER::Render(unsigned long first_vertex, unsigned long num_primitives, DWORD type)
{
    if(_graphics->Get_Device_COM() == NULL || _vertex_buffer == NULL)
        return FALSE;

    // binds a vertex buffer to a device data stream
    _graphics->Get_Device_COM()->SetStreamSource(0, _vertex_buffer, 0, _vertex_size);

    // sets the current vertex stream declaration
    _graphics->Get_Device_COM()->SetFVF(_fvf);

    // Renders a sequence of nonindexed, geometric primitives of the specified type from the current set
    // of data input streams.
    _graphics->Get_Device_COM()->DrawPrimitive((D3DPRIMITIVETYPE) type, first_vertex, num_primitives);

    return TRUE;
}

//---------------------------------------------------------------------------
// Lock vertex buffer from specified position with specified length.
//---------------------------------------------------------------------------
BOOL VERTEX_BUFFER::Lock(unsigned long first_vertex, unsigned long num_vertices)
{
    if(_vertex_buffer == NULL)
        return FALSE;

    // locks a range of vertex data and obtains a pointer to the vertex buffer memory
    if(FAILED(_vertex_buffer->Lock(first_vertex * _vertex_size, num_vertices * _vertex_size, (void**)&_ptr, 0)))
        return FALSE;

    _is_locked = TRUE;

    return TRUE;
}

//---------------------------------------------------------------------------
// Unlock vertex buffer.
//---------------------------------------------------------------------------
BOOL VERTEX_BUFFER::Unlock()
{
    if(_vertex_buffer == NULL)
        return FALSE;

    if(FAILED(_vertex_buffer->Unlock()))
        return FALSE;

    _is_locked = FALSE;

    return TRUE;
}

//---------------------------------------------------------------------------
// Check whether vertex buffer has created successfully.
//---------------------------------------------------------------------------
BOOL VERTEX_BUFFER::Is_Loaded()
{
    return _vertex_buffer ? TRUE : FALSE;
}

//---------------------------------------------------------------------------
// Ger pointer to vertex data.
//---------------------------------------------------------------------------
void* VERTEX_BUFFER::Get_Ptr()
{
    return (void*)_ptr;
}

首先必须使用VERTEX_BUFFER::Create函数创建顶点缓冲，此函数的参数有GRAPHICS对象、用于分配空间的顶点数、单个顶点的大小（单位是字节）、可变顶点格式（FVF）。由此可以看出，要使用这个类，还需要创建一个顶点结构体。

要记得在处理完类的实例后，调用VERTEX_BUFFER::Free函数释放它。但是，在释放类的实例之前，需要调用 VERTEX_BUFFER::Set函数给缓冲区填充要使用的顶点信息。VERTEX_BUFFER::Set函数的参数包括要设置的第一个顶点的索引、要设置的顶点数目、一个指向自定义顶点结构体数组的指针。

经过以上的准备，就可以使用VERTEX_BUFFER::Render函数渲染多边形了，注意可以指定开始绘制的第一个顶点以及要绘制的图元（多边形的面）的总数目。

type参数的含义如下表所示：

标志	说明
D3DPT_POINTLIST	将顶点通过单独的点集合方式进行渲染。
D3DPT_LINELIST	将顶点通过单独的线段集合方式进行渲染。
D3DPT_LINESTRIP	一连串的线段，每条线段都是从前一个顶点到当前顶点绘制而成。
D3DPT_TRIANGLELIST	三角形列，其中每个三角形都有三个独享的顶点。
D3DPT_TRIANGLESTRIP	三角形带，每个顶点都使用前面两个顶点来形成一个面。
D3DPT_TRIANGLEFAN	三角形扇，每个顶点都使用一个中心顶点和另外两个顶点形成一个面。

其中三角形列、带、扇示意图如下：

下面给出测试代码：

点击下载源码和工程

/*****************************************************************************
PURPOSE:
    Test for class VERTEX_BUFFER.
*****************************************************************************/

#include "Core_Global.h"

#pragma warning(disable : 4996)

//===========================================================================
// Defines class APP which public inherits from class APPLICATION.
//===========================================================================
class APP : public APPLICATION
{
private:
    GRAPHICS  _graphics;
    VERTEX_BUFFER _vertex_buffer;

    // 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)

public:
    BOOL Init();
    BOOL Shutdown();
    BOOL Frame();
};

//-----------------------------------------------------------------------------
// Initialize graphics, set display mode, set vertex buffer.
//-----------------------------------------------------------------------------
BOOL APP::Init()
{
    // initialize vertex data
    VERTEX verts[] = {
      { 100.0f, 100.0f, 1.0f, 1.0f, D3DCOLOR_RGBA(0,64,128,255) },
      { 300.0f, 100.0f, 1.0f, 1.0f, D3DCOLOR_RGBA(0,64,128,255) },
      { 100.0f, 300.0f, 1.0f, 1.0f, D3DCOLOR_RGBA(0,64,128,255) },
      { 300.0f, 300.0f, 1.0f, 1.0f, D3DCOLOR_RGBA(0,64,128,255) },
      {  50.0f, 150.0f, 1.0f, 1.0f, D3DCOLOR_RGBA(128,0,0,128)  },
      { 350.0f, 150.0f, 1.0f, 1.0f, D3DCOLOR_RGBA(128,0,0,128)  },
      {  50.0f, 350.0f, 1.0f, 1.0f, D3DCOLOR_RGBA(128,0,0,128)  },
      { 350.0f, 350.0f, 1.0f, 1.0f, D3DCOLOR_RGBA(128,0,0,128)  }
    };

    // initialize graphics
    if (! _graphics.Init())
        return FALSE;

    // set display mode for graphics
    if(! _graphics.Set_Mode(Get_Hwnd(), TRUE, FALSE, 400, 400, 16))
        return FALSE;

    // create the vertex buffer
    _vertex_buffer.Create(&_graphics, 8, sizeof(VERTEX), VERTEX_FVF);

    // Copy vertex data from VertexList to vertex buffer.
    _vertex_buffer.Set(0, 8, verts);

    return TRUE;
}

//-----------------------------------------------------------------------------
// Release all d3d resource.
//-----------------------------------------------------------------------------
BOOL APP::Shutdown()
{
    // Free vertex buffer resource, reset data member.
     _vertex_buffer.Free();

    return TRUE;
}

//-----------------------------------------------------------------------------
// Render a frame.
//-----------------------------------------------------------------------------
BOOL APP::Frame()
{
    // clear display with specified color
    _graphics.Clear_Display(D3DCOLOR_RGBA(0, 0, 0, 255));

    // begin scene
    if(_graphics.Begin_Scene())
    {
        // 1) disable alpha blending first
        _graphics.Enable_Alpha_Blending(FALSE);

        // Render vertex buffer into display.
        _vertex_buffer.Render(0, 2, D3DPT_TRIANGLESTRIP);

        // 2) enable alpha blending now
        _graphics.Enable_Alpha_Blending(TRUE);

        // Render vertex buffer into display.
        _vertex_buffer.Render(4, 2, D3DPT_TRIANGLESTRIP);

        // end the scene
        _graphics.End_Scene();
    }

    // display video buffer
    _graphics.Display();

    return TRUE;
}

int PASCAL WinMain(HINSTANCE inst, HINSTANCE, LPSTR cmd_line, int cmd_show)
{
    APP app;

    return app.Run();
}

运行截图：

posted on 2007-09-03 21:33 lovedday 阅读(344) 评论(0) 编辑收藏引用

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