2013年8月30日星期五（8-3多边形）

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本文介绍了一种使用自定义结构体实现2D多边形的绘制方法，并通过实例展示了如何初始化多边形顶点、设置状态及颜色，以及如何在屏幕上绘制并更新这些多边形的位置。

设定了端点和多边形两个结构体

// a 2D vertex

typedef struct VERTEX2DI_TYP

{

int x,y; // the vertex

} VERTEX2DI, *VERTEX2DI_PTR;

// a 2D polygon

typedef struct POLYGON2D_TYP

{

int state; // state of polygon

int num_verts; // number of vertices

int x0,y0; // position of center of polygon

int xv,yv; // initial velocity

DWORD color; // could be index or PALETTENTRY

VERTEX2DI *vlist; // pointer to vertex list

} POLYGON2D, *POLYGON2D_PTR;

其实就是绘制封闭线段。在上节的基础上，

初始化代码如下述：

// define points of asteroid

VERTEX2DI asteroid_vertices[8] = {33,-3, 9,-18, -12,-9, -21,-12, -9,6, -15,15, -3,27, 21,21};

// loop and initialize all asteroids

for (int curr_index = 0; curr_index < NUM_ASTEROIDS; curr_index++)

{

// initialize the asteroid

asteroids[curr_index].state = 1; // turn it on

asteroids[curr_index].num_verts = 8;

asteroids[curr_index].x0 = rand()%SCREEN_WIDTH; // position it

asteroids[curr_index].y0 = rand()%SCREEN_HEIGHT;

asteroids[curr_index].xv = -8 + rand()%17;

asteroids[curr_index].yv = -8 + rand()%17;

asteroids[curr_index].color = rand()%256;

asteroids[curr_index].vlist = new VERTEX2DI [asteroids[curr_index].num_verts];

for (int index = 0; index < asteroids[curr_index].num_verts; index++)

asteroids[curr_index].vlist[index] = asteroid_vertices[index];

} // end for curr_index

在game_main()中，确定边界

DDraw_Fill_Surface( lpddsback, 0 );

DDRAW_INIT_STRUCT( ddsd );

lpddsback->Lock( NULL, & ddsd, DDLOCK_WAIT | DDLOCK_SURFACEMEMORYPTR, NULL );

for( int curr_index = 0; curr_index < NUM_ASTEROIDS; curr_index ++ )

{

asteroids[curr_index].color = rand() % 256;

Draw_Polygon2D( & asteroids[curr_index], ( UCHAR * )ddsd.lpSurface, ddsd.lPitch );

asteroids[curr_index].x0 += asteroids[curr_index].xv;

asteroids[curr_index].y0 += asteroids[curr_index].yv;

if( asteroids[curr_index].x0 > SCREEN_WIDTH + 100 )

asteroids[curr_index].x0 = -100;

if( asteroids[curr_index].y0 > SCREEN_HEIGHT + 100 )

asteroids[curr_index].y0 = -100;

if( asteroids[curr_index].x0 < - 100 )

asteroids[curr_index].x0 = SCREEN_WIDTH + 100;

if( asteroids[curr_index].y0 < - 100 )

asteroids[curr_index].y0 = SCREEN_HEIGHT + 100;

}

lpddsback->Unlock( NULL );

while( FAILED( lpddsprimary->Flip( NULL, DDFLIP_WAIT ) ) );

Sleep( 33 );

结果如图所示

封装，

加个成员变量

int DDRAW_Interface::Draw_Polygon2D( POLYGON2D_PTR poly, UCHAR * vbuffer, int lpitch )

{

int index = 0;

if( poly->state )

{

for(index = 0; index < poly->num_verts - 1; index ++ )

{

Draw_Clip_Line( poly->vlist[index].x + poly->x0,

poly->vlist[index].y + poly->y0,

poly->vlist[index+1].x + poly->x0,

poly->vlist[index+1].y + poly->y0,

poly->color,

vbuffer, lpitch );

}

Draw_Clip_Line( poly->vlist[0].x + poly->x0,

poly->vlist[0].y + poly->y0,

poly->vlist[index].x + poly->x0,

poly->vlist[index].y + poly->y0,

poly->color,

vbuffer, lpitch );

return ( 1 );

}

else

return ( 0 );

}

在main()中

POLYGON2D asteroids[64];

VERTEX2DI asteroid_vertices[8] = { 30, -3, 9, -18, -12, -9, -21, -12, -9, 6, -15, 15, -3, 27, 21, 21 };

for( int curr_index = 0; curr_index < NUM_ASTEROIDS; curr_index ++ )

{

asteroids[curr_index].state= 1;

asteroids[curr_index].num_verts = 8;

asteroids[curr_index].x0 = rand() % SCREEN_WIDTH;

asteroids[curr_index].y0 = rand() % SCREEN_HEIGHT;

asteroids[curr_index].xv = -8 + rand() % 17;

asteroids[curr_index].yv = -8 + rand() % 17;

asteroids[curr_index].color = rand() % 256;

asteroids[curr_index].vlist = new VERTEX2DI[asteroids[curr_index].num_verts];

for( int index = 0; index < asteroids[curr_index].num_verts; index ++ )

asteroids[curr_index].vlist[index] = asteroid_vertices[index];

}

在GAME_MAIN（）中

ddraw->DDraw_Fill_Surface( ddraw->getbackSurface(), 0 );

ddraw->DDraw_Lock_Back_Surface();

for( int curr_index = 0; curr_index < 64; curr_index ++ )

{

asteroids[curr_index].color = rand() % 256;

ddraw->Draw_Polygon2D( & asteroids[curr_index], ddraw->getbackbuffer(), ddraw->getbacklpitch() );

asteroids[curr_index].x0 += asteroids[curr_index].xv;

asteroids[curr_index].y0 += asteroids[curr_index].yv;

if( asteroids[curr_index].x0 > SCREEN_WIDTH + 100 )

asteroids[curr_index].x0 = -100;

if( asteroids[curr_index].y0 > SCREEN_HEIGHT + 100 )

asteroids[curr_index].y0 = -100;

if( asteroids[curr_index].x0 < - 100 )

asteroids[curr_index].x0 = SCREEN_WIDTH + 100;

if( asteroids[curr_index].y0 < - 100 )

asteroids[curr_index].y0 = SCREEN_HEIGHT + 100;

}

ddraw->DDraw_Unlock_Back_Surface();

while( FAILED( ddraw->DDraw_Flip() ) );

Sleep( 33 );

下一步根据t3dlib进行封装。今天下午做个大清理吧，从头看到尾，

先看下DDRAW_Shutdown();,析构函数重新整理

DDRAW_Interface::~DDRAW_Interface()

{

if( m_lpddclipper )

m_lpddclipper->Release();

if( m_lpddclipperwin )

m_lpddclipperwin->Release();

if( m_lpddsback )

{

m_lpddsback->Release();

}

// now the primary surface

if (m_lpddsprimary)

{

m_lpddsprimary->Release();

} // end if

if (m_lpddpal)

{

m_lpddpal->Release();

} // end if

if( m_lpdd )

{

m_lpdd->Release();

}

USHORT DDRAW_Interface::RGB16Bit565( int r, int g, int b )

{

r >>= 3;

g >>= 2;

b >>= 3;

return ( _RGB16BIT565( ( r ), ( g ), ( b ) ) );

}

int DDRAW_Interface::Draw_Pixel16( int x, int y, int color, USHORT * video_buffer, int lpitch16 )

{

( ( USHORT * ) video_buffer )[x + y * ( lpitch16 >> 1 )] = color;

return ( 1 );

}

int DDRAW_Interface::Draw_Text_GDI( char * text, int x, int y, COLORREF color, LPDIRECTDRAWSURFACE7 lpdds )

{

HDC xdc;

if( FAILED( lpdds->GetDC( & xdc ) ) )

return ( 0 );

SetTextColor( xdc, color );

SetBkMode( xdc, TRANSPARENT );

TextOut( xdc, x, y, text, strlen( text ) );

lpdds->ReleaseDC( xdc );

return 1;

}

int DDRAW_Interface::Draw_Text_GDI( char * text, int x, int y, int color, LPDIRECTDRAWSURFACE7 lpdds )

{

HDC xdc;

if( FAILED( lpdds->GetDC( & xdc ) ) )

return ( 0 );

SetTextColor( xdc, RGB( palette[color].peRed,palette[color].peGreen,palette[color].peBlue ) );

SetBkMode( xdc, TRANSPARENT );

TextOut( xdc, x, y, text, strlen( text ) );

lpdds->ReleaseDC( xdc );

return 1;

}