D3D描绘四边形的四种方法之DrawPrimitive、DrawIndexedPrimitive、DrawPrimitiveUP、DrawIndexedPrimitiveUP

创建描绘四边形的四种方法：（程序片段，只是简要介绍不同之处，不对之处，恳请指正）

第一种：最常用的一种：

使用D3D坐标（D3DFVF_XYZ ），通过设置矩阵，使用VB, 4个点。调用DrawPrimitive（）；

使用6个顶点时也可以，在render时需要使用

g_pd3dDevice->DrawPrimitive( D3DPT_TRIANGLELIST, 0, 2 );

LPDIRECT3D9 g_pD3D = NULL;// Used to create the D3DDevice

LPDIRECT3DDEVICE9 g_pd3dDevice = NULL; // Our rendering device

LPDIRECT3DVERTEXBUFFER9 g_pVB = NULL; // Buffer to hold Vertices'

LPDIRECT3DINDEXBUFFER9 g_pIB = NULL;

VOID* pVertices;

struct CUSTOMVERTEX

{

FLOAT x, y, z;

DWORD color;

};

CUSTOMVERTEX Vertices[] =

{

{ -1.0f, -1.0f, 1.f, 0xffff0000, },//左下

{ -1.0f, 1.0f, 1.f, 0xff00ff00, },//左上

{ 1.0f, -1.0f, 1.f, 0xff00ff00, },//右下

{ 1.0f, 1.0f, 1.f, 0xff00ff00, },//右上

};

#define D3DFVF_CUSTOMVERTEX (D3DFVF_XYZ | D3DFVF_DIFFUSE)

HRESULT InitVB()

{

HRESULT hr = E_FAIL;

{

hr = g_pd3dDevice->CreateVetexBuffer( 4 * sizeof(CUSTOMVERTEX), 0, D3DFVF_CUSTOMVERTEX, D3DPOOL_DEFAULT, &g_pVB, NULL) ;

If(E_FAIL == hr)

{ Break; }

hr = g_pVB->Lock( 0, sizeof( Vertices ), ( void** )&pVertices, 0 )

If(E_FAIL == hr)

{ Break; }

memcpy( pVertices, Vertices, sizeof( Vertices ) );

g_pVB->Unlock();

// create index buffer

#if 0

int fIB[] = {0,1,2,2,1,3,};

if (FAILED(g_pd3dDevice->CreateIndexBuffer( sizeof(fIB), D3DUSAGE_DYNAMIC, D3DFMT_INDEX32, D3DPOOL_DEFAULT, &g_pIB, NULL)))

{ return E_FAIL; }

void *pIndexs;

if (FAILED(g_pIB->Lock(0, sizeof(fIB),&pIndexs,D3DLOCK_DISCARD)))

{ return E_FAIL; }

memcpy(pIndexs, fIB, sizeof(fIB)); g_pIB->Unlock();

#endif

}while(false)

return hr；

}

//set world view project matrix.

VOID SetupMatrices()

{ D3DXMATRIXA16 matWorld;

// Set up the rotation matrix to generate 1 full rotation (2*PI radians)

// every 1000 ms. To avoid the loss of precision inherent in very high

// floating point numbers, the system time is modulated by the rotation

// period before conversion to a radian angle.

UINT iTime = timeGetTime() % 1000;

FLOAT fAngle = iTime * ( 2.0f * D3DX_PI ) / 1000.0f;

D3DXMatrixRotationX( &matWorld, fAngle );

g_pd3dDevice->SetTransform( D3DTS_WORLD, &matWorld );

D3DXVECTOR3 vEyePt( 0.0f, 0.0f, -5.0f );

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 );

D3DXMATRIXA16 matProj;

D3DXMatrixPerspectiveFovLH( &matProj, D3DX_PI / 4, 1.778f, 1.0f, 100.0f );

g_pd3dDevice->SetTransform( D3DTS_PROJECTION, &matProj ); }

//render

VOID Render()

{

//USE VB,don't use IB.

//use D3DFVF_XYZ FVF,it’s should call SetupMatrices() SetupMatrices();

g_pd3dDevice->SetStreamSource( 0, g_pVB, 0, sizeof( CUSTOMVERTEX ));

g_pd3dDevice->SetFVF( D3DFVF_CUSTOMVERTEX );

g_pd3dDevice->DrawPrimitive( D3DPT_TRIANGLESTRIP, 0, 2 );

#if 0 // use VB and IB.

SetupMatrices();

g_pd3dDevice->SetStreamSource( 0, g_pVB, 0, sizeof( CUSTOMVERTEX ));

g_pd3dDevice->SetFVF( D3DFVF_CUSTOMVERTEX );

g_pd3dDevice->SetIndices(g_pIB);

g_pd3dDevice->DrawIndexedPrimitive( D3DPT_TRIANGLELIST, 0, 0,4,0,2 );

#endif

}

第二种：使用顶点缓冲区和索引缓冲区，且使用DrawIndexedPrimitive（）。

第三种：使用屏幕坐标，D3DFVF_XYZRHW，而不使用D3DFVF_XYZ。这个时候不需要使用顶点缓冲区和索引缓冲区。

在render的时候，不需要设置world、view、project矩阵。调用DrawPrimitiveUP（）。

struct CUSTOMVERTEX_RHW

{

FLOAT x, y, z, rhw; // The transformed position for the vertex

DWORD color; // The vertex color }; // Initialize three Vertices for rendering a triangle

CUSTOMVERTEX_RHW Verticesrhw[] =

{

{ 50.0f, 150.0f, 0.5f, 1.0f, 0xff00ffff, },

{ 50.0f, 50.0f, 0.5f, 1.0f, 0xffff0000, },

{ 150.0f, 150.0f, 0.5f, 1.0f, 0xff00ffff, },

{ 150.0f, 50.0f, 0.5f, 1.0f, 0xff00ff00, },

};

Void render()

{

//SetupMatrices();

//g_pd3dDevice->SetStreamSource( 0, g_pVB, 0, sizeof( CUSTOMVERTEX ));

g_pd3dDevice->SetFVF( D3DFVF_CUSTOMVERTEX_RHW);

//g_pd3dDevice->DrawPrimitive( D3DPT_TRIANGLESTRIP, 0, 2 );

//g_pd3dDevice->SetIndices(g_pIB);

//g_pd3dDevice->DrawIndexedPrimitive( D3DPT_TRIANGLELIST, 0, 0,4,0,2 );

g_pd3dDevice->DrawPrimitiveUP( D3DPT_TRIANGLESTRIP, 2, (void*)Verticesrhw, sizeof(CUSTOMVERTEX_RHW)); }

第四种：使用屏幕坐标，D3DFVF_XYZRHW，而不使用D3DFVF_XYZ。这个时候不需要使用顶点缓冲区和索引缓冲区。

在render的时候，不需要设置world、view、project矩阵。调用DrawIndexedPrimitiveUP（）。

与第三种方法相比，只是多了一个顶点索引设置。