前面我们已经学习了点和线的绘制,本篇我们继续绘图函数学习----矩形的绘制，也就是长方形的绘制,并给出一个绘制楼房的例子演示矩形的应用。

所有绘制矩形相关函数如下：

//以下矩形左上角坐标(left, top)，右下角坐标(right,bottom )
//以线条颜色绘制边框，以填充颜色填充内部
 
//画无填充矩形
void rectangle( int left, int top, int right, int bottom );
 
//画无边框填充矩形
void solidrectangle( int left, int top, int right, int bottom );
 
//画填充矩形
void fillrectangle( int left, int top, int right, int bottom );
 
//清空矩形，以背景色清空矩形
void clearrectangle( int left, int top, int right, int bottom );

可以看到有四个绘制函数,而且参数都是一致的,参数标明矩形左上角坐标，及右下角坐标 。

四个函数效果分别是：

1、画无填充矩形  rectangle
 
2、画无边框填充矩形 solidrectangle

3、画填充矩形 fillrectangle 
 
4、清空矩形，以背景色清空矩形 clearrectangle 

我们以后会看到所有针对类似矩形这种具有面积的图形,都分别实现四种绘制效果,分别是1、无填充--不带有前缀,2、无边框--solid开头，3、带边框及填充--fill开头，4、清空形状区域，也就是以背景色填充。

下面用一个随机城市建筑的绘制例程展示矩形的简单应用:

// Building.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"

#include "../import/include/CGBoard.h"
#include "math.h"

#ifdef _DEBUG
#pragma comment(lib,"../import/lib/SimpleCG_MDd.lib")
#else
#pragma comment(lib,"../import/lib/SimpleCG_MD.lib")
#endif

#define SUBCOLOR(x,y) ((x-y)<0?0:(x-y))
#define ADDCOLOR(x,y) ((x+y)>255?255:(x+y))
int g_nWidth = 600;		//画面宽度
int g_nHeight= 600;		//画面高度

//画建筑的窗户1
void DrawWindow1( int nX, int nY, int nWidth, int nHeight, int nWidthCnt, int nHeightCnt )
{
	int i;
	int j;
	if(nWidthCnt<=0||nHeightCnt<=0)
		return;
	int nWidthWindow = nWidth / nWidthCnt;
	int nHeightWindow = nHeight / nHeightCnt;
	setfillcolor(RGB(rand()%200,130,180));
	for( j=0; j<nHeightCnt; j++ )
		for( i=0; i<nWidthCnt; i++ )
		{
			//画填充矩形
			fillrectangle( nX+nWidthWindow*i, nY+nHeightWindow*j, nX+nWidthWindow*i+nWidthWindow-5, nY+nHeightWindow*j+nHeightWindow-3 );
		}
}
//画建筑的窗户2
void DrawWindow2( int nX, int nY, int nWidth, int nHeight, int nHeightCnt )
{
	int i;
	int j;
	if(nHeightCnt<=0)
		return;
	int nHeightWindow = nHeight / nHeightCnt;
	setfillcolor(RGB(rand()%255,rand()%255,rand()%255));
	//画填充矩形
	fillrectangle( nX, nY, nX+nWidth, nY+nHeight );
	setfillcolor(RGB(200+rand()%55,200+rand()%55,200+rand()%55));
	for( j=0; j<nHeightCnt; j++ )
	{
		//填充矩形画横边
		solidrectangle( nX+1, nY+nHeightWindow*j, nX+nWidth, nY+nHeightWindow*j+3 );
	}
	//填充矩形画竖边
	if(rand()%2)
	{
		solidrectangle( nX+nWidth/5, nY, nX+nWidth/5+10, nY+nHeight );
		solidrectangle( nX+nWidth*4/5, nY, nX+nWidth*4/5+10, nY+nHeight );
	}
}
//画建筑的窗户3
void DrawWindow3( int nX, int nY, int nWidth, int nHeight, COLORREF  nColor )
{
	int i;
	int j;
	int nWidthCnt = nWidth / 10;
	int nHeightCnt = nHeight / 10;
	int r=GetRValue(nColor);
	int g=GetGValue(nColor);
	int b=GetBValue(nColor);
	setfillcolor(RGB( SUBCOLOR(r,50),SUBCOLOR(g,50),SUBCOLOR(b,50) ));
	//画填充矩形
	solidrectangle( nX, nY, nX+nWidth, nY+nHeight );
	r=GetRValue(nColor);
	g=GetGValue(nColor);
	b=GetBValue(nColor);
	setfillcolor(RGB( ADDCOLOR(r,30),ADDCOLOR(g,30),ADDCOLOR(b,30) ));
	for( i=1; i<nWidthCnt; i++ )
	{
		//画填充矩形
		solidrectangle( nX+10*i, nY, nX+10*i+3, nY+nHeight );
	}
	for( i=1; i<nHeightCnt; i++ )
	{
		//画填充矩形
		solidrectangle( nX, nY+10*i, nX+nWidth, nY+10*i+3 );
	}	
}
//画建筑类型1
void DrawBuilding1( int nX, int nY, int nWidth, int nHeight )
{
	int nWidthCnt = (nWidth-10) / 20;
	int nHeightCnt = (nHeight-10) / 30;
	//画填充矩形
	COLORREF  nColor= RGB(rand()%255,rand()%255,rand()%255);
	if(rand()%2)
	{
		//房顶
		if(rand()%2)
		{
			setfillcolor(RGB(0,0,0));
			fillrectangle( nX + nWidth-nWidth/4, nY - nHeight-80, nX + nWidth-nWidth/4+3, nY - nHeight );
		}
		setfillcolor(nColor);
		if(rand()%2)
		{
			fillrectangle( nX + nWidth-nWidth/4-20, nY - nHeight-40, nX + nWidth-20-nWidth/4+20, nY - nHeight );
		}
		fillrectangle( nX+20, nY - nHeight-20, nX + nWidth-20, nY - nHeight );
	}
	setfillcolor(nColor);
	fillrectangle( nX, nY - nHeight, nX + nWidth, nY );
	int nWindowType=rand()%2;
	switch(nWindowType)
	{
	case 1:
		DrawWindow1( nX+(nWidth-nWidthCnt*20)/2, nY - nHeight+(nHeight-nHeightCnt*30)/2, nWidthCnt*20, nHeightCnt*30, nWidthCnt, nHeightCnt );
		break;
	default:
		nWidthCnt = (nWidth-10) / 20;
		nHeightCnt = (nHeight-10) / 10;
		DrawWindow2( nX+(nWidth-nWidthCnt*20)/2, nY - nHeight+(nHeight-nHeightCnt*10)/2, nWidthCnt*20, nHeightCnt*10, nHeightCnt );
		break;
	}
}
//画建筑类型2
void DrawBuilding2( int nX, int nY, int nWidth, int nHeight )
{
	int nFloorHeight=nHeight/3;
	int nFloorWidth=nWidth/3;
	int nWidthCnt = (nFloorWidth-10) / 20;
	int nHeightCnt = (nFloorHeight-6) / 30;
	COLORREF  nColor= RGB(rand()%255,rand()%255,rand()%255);
	
	//房顶
	if(rand()%2)
	{
		setfillcolor(RGB(0,0,0));
		fillrectangle( nX + nFloorWidth/4, nY - nHeight-80, nX + nFloorWidth/4+3, nY - nHeight );
	}
	//房体
	//画填充矩形
	setfillcolor(nColor);
	fillrectangle( nX, nY - nHeight, nX + nFloorWidth, nY - nHeight + nFloorHeight );
	DrawWindow1( nX+(nFloorWidth-nWidthCnt*20)/2, nY - nHeight+(nFloorHeight-nHeightCnt*30)/2, nWidthCnt*20, nHeightCnt*30, nWidthCnt, nHeightCnt );
	fillrectangle( nX, nY - nHeight + nFloorHeight, nX + nFloorWidth*2, nY - nHeight + nFloorHeight*2 );
	DrawWindow1( nX+(nFloorWidth-nWidthCnt*20)/2, nY - nHeight+nFloorHeight+(nFloorHeight-nHeightCnt*30)/2, nWidthCnt*40, nHeightCnt*30, nWidthCnt*2, nHeightCnt );
	fillrectangle( nX, nY - nHeight + nFloorHeight*2, nX + nWidth, nY );
	DrawWindow1( nX+(nFloorWidth-nWidthCnt*20)/2, nY - nHeight+nFloorHeight*2+(nFloorHeight-nHeightCnt*30)/2, nWidthCnt*60, nHeightCnt*30, nWidthCnt*3, nHeightCnt );
}
void DrawBuilding3Floor( int nX, int nY, int nWidth, int nHeight, COLORREF  nColor )
{
	//画填充矩形
	int nPad=5;
	setfillcolor(nColor);
	fillrectangle( nX, nY, nX + nWidth, nY + nHeight );
	DrawWindow3( nX+nPad, nY +nPad, nWidth-nPad*2, nHeight  - nPad*2, nColor );
}
//画建筑类型3
void DrawBuilding3( int nX, int nY, int nWidth, int nHeight )
{
	int i;
	int nPad=3;
	int nInner=10;
	int nWindowWidth=10;
	int nFloorHeight=nHeight/8;
	int nWidthCnt = (nWidth-30) / nWindowWidth;
	int nHeightCnt = (nFloorHeight-10) / nWindowWidth;
	COLORREF  nColor= RGB(rand()%200,rand()%200,rand()%200);

	int y=nY;
	for( i=0; i<8; i++ )
	{
		if(i%2==0)
			nInner = 10;
		else
			nInner = 0;
		DrawBuilding3Floor( nX+nInner, y-nFloorHeight, nWidth, nFloorHeight, nColor);
		y -= nFloorHeight;
	}
}
void DrawProcess()
{
	int i;
	line( 0, g_nHeight-80, g_nWidth, g_nHeight-80 );
	
	for( i=0; i<8; i++ )
	{
		int nWindowType=rand()%3;
		switch(nWindowType)
		{
		case 1:
			DrawBuilding1( rand()%500, g_nHeight-80, 100+rand()%200, 220+rand()%200 );
			break;
		case 2:
			DrawBuilding2( rand()%500, g_nHeight-80, 100+rand()%200, 220+rand()%200 );
			break;
		default:
			DrawBuilding3( rand()%500, g_nHeight-80, 100+rand()%200, 220+rand()%200 );
			break;
		}
	}
	//马路
	setfillcolor(0);
	fillrectangle( 0, g_nHeight-80, g_nWidth, g_nHeight );
	setfillcolor(RGB(255,255,2555));
	for( i=0; i<g_nWidth; i+=100 )
	{
		solidrectangle( i, g_nHeight-60, i+50, g_nHeight-50 );
	}
}
int _tmain(int argc, _TCHAR* argv[])
{
	srand(GetTickCount());
	//初始化
	if( !ShowingBoard(g_nWidth,g_nHeight, DrawProcess))
		return 1;
	//关闭图库
	CloseBoard();
	return 0;
}

可以看到所有图形元素都是用矩形绘制，发挥你的想象，你一定能发现矩形的更多更好玩的用法。

运行界面：

 每次运行都随机生成各种建筑，我只构建了简单的三种建筑类型，你可以尝试修改代码，绘制更多更有趣的建筑。赶紧动起手来吧。