首先看一下效果图：

分为4部分，先看代码最少的计算模块：

**********Calculation.h*******************#pragma onceclass sAcGePoint2d;class AcGePoint3d;class CCalculation{public:	CCalculation(void);	~CCalculation(void);	//计算两点连线的中点	static AcGePoint2d MiddlePoint(AcGePoint2d pt1, AcGePoint2d pt2);	static AcGePoint3d MiddlePoint(AcGePoint3d pt1, AcGePoint3d pt2);	static AcGePoint3d Pt2dTo3d(AcGePoint2d pt);	//计算常量π的值	static double PI();};

**********Calculation.cpp*******************#include "StdAfx.h"#include "Calculation.h"#include 
    
     CCalculation::CCalculation(void){}CCalculation::~CCalculation(void){}AcGePoint2d CCalculation::MiddlePoint(AcGePoint2d pt1, AcGePoint2d pt2){	AcGePoint2d pt;	pt[X] = (pt1[X] + pt2[X]) / 2;	pt[Y] = (pt1[Y] + pt2[Y]) / 2;	return pt;}AcGePoint3d CCalculation::MiddlePoint(AcGePoint3d pt1, AcGePoint3d pt2){	AcGePoint3d pt;	pt[X] = (pt1[X] + pt2[X]) / 2;	pt[Y] = (pt1[Y] + pt2[Y]) / 2;	pt[Z] = (pt1[Z] + pt2[Z]) / 2;	return pt;}AcGePoint3d CCalculation::Pt2dTo3d(AcGePoint2d pt){	AcGePoint3d ptTemp(pt.x, pt.y, 0);	return ptTemp;}double CCalculation::PI(){	return 4 * atan(1.0);//反正切}
    

然后我们看一下，修改颜色，图层，线条：

**********CModifyEnt.h*******************#pragma once#include "StdAfx.h"class CModifyEnt{public:	CModifyEnt(void);	~CModifyEnt(void);	//改变颜色	static Acad::ErrorStatus ChangeColor(AcDbObjectId entId, Adesk::UInt16 colorIndex);	//改变图层	static Acad::ErrorStatus ChangeLayer(AcDbObjectId entId,CString strLayerName);	//改变线型	static Acad::ErrorStatus ChangeLinetype(AcDbObjectId entId,CString strLinetype);};

**********CModifyEnt.cpp*******************#include "StdAfx.h"#include "ModifyEnt.h"CModifyEnt::CModifyEnt(void){}CModifyEnt::~CModifyEnt(void){}Acad::ErrorStatus CModifyEnt::ChangeColor(AcDbObjectId entId, Adesk::UInt16 colorIndex){	AcDbEntity *pEntity = NULL;	// 打开图形数据库中的对象	acdbOpenObject(pEntity, entId, AcDb::kForWrite);	// 修改实体的颜	pEntity->setColorIndex(colorIndex);// colorIndex:0～256 的值，其中 0 代表随块，256 代表随层	// 用完之后，及时关闭	pEntity->close();	return Acad::eOk;}Acad::ErrorStatus CModifyEnt::ChangeLayer(AcDbObjectId entId, CString strLayerName){	AcDbEntity *pEntity = NULL;	// 打开图形数据库中的对象	acdbOpenObject(pEntity, entId, AcDb::kForWrite);	// 修改实体的图层	pEntity->setLayer(strLayerName);	// 用完之后，及时关闭	pEntity->close();	return Acad::eOk;}Acad::ErrorStatus CModifyEnt::ChangeLinetype(AcDbObjectId entId, CString strLinetype){	AcDbEntity *pEntity = NULL;	// 打开图形数据库中的对象	acdbOpenObject(pEntity, entId, AcDb::kForWrite);	// 修改实体的线型	pEntity->setLayer(strLinetype);	// 用完之后，及时关闭	pEntity->close();	return Acad::eOk;}

接下来，我们看最重要的一部分，创建直线，创建圆（4种方法），创建圆弧（5种方法）：

**********CreateEnt.h*******************#pragma once#include "StdAfx.h"class CCreateEnt{public:	CCreateEnt(void);	~CCreateEnt(void);	// 将实体添加到图形数据库的模型空间	static AcDbObjectId PostToModelSpace(AcDbEntity* pEnt);	// 创建一条线	static AcDbObjectId CreateLine(AcGePoint3d ptStart,AcGePoint3d ptEnd); 		//创建一个圆(圆心、半径法)（三维）	// ptCenter：圆心； 	//radius：半径；	//vec：圆所在平面	static AcDbObjectId CreateCircle(AcGePoint3d ptCenter, AcGeVector3d vec, double radius);	//创建位于 XOY 平面上的圆（二维）依赖三维法	static AcDbObjectId CreateCircle(AcGePoint3d ptCenter, double radius);	//创建一个圆（俩点法）依赖二维法	static AcDbObjectId CreateCircle(AcGePoint2d pt1, AcGePoint2d pt2);	//创建一个圆（三点法）依赖二维法	static AcDbObjectId CreateCircle(AcGePoint2d pt1, AcGePoint2d pt2,AcGePoint2d pt3);	//创建圆弧（圆心、半径、圆弧所在的平面、起点角度和终点角度）	//ptCenter：圆心； 	//vec：圆弧所在平面	//radius：半径；	//startAngle:起点角度	//endAngle：终点角度	static AcDbObjectId CreateArc(AcGePoint3d ptCenter, AcGeVector3d vec, double radius, double startAngle, double endAngle);	//创建圆弧（二维）依赖于圆弧1法	static AcDbObjectId CreateArc(AcGePoint2d ptCenter, double radius, double startAngle, double endAngle);	//创建圆弧（三点法）依赖于二维法	static AcDbObjectId CreateArc(AcGePoint2d ptStart, AcGePoint2d ptOnArc, AcGePoint2d ptEnd);	//创建圆弧（起点、圆心、终点）依赖于二维法	static AcDbObjectId CreateArcSCE(AcGePoint2d ptStart, AcGePoint2d ptCenter, AcGePoint2d ptEnd);	//创建圆弧(起点、圆心、圆弧角度)依赖于二维法	static AcDbObjectId CreateArc(AcGePoint2d ptStart, AcGePoint2d ptCenter, double angle);};

**********Calculation.cpp*******************#include "StdAfx.h"#include "CreateEnt.h"#include "Calculation.h"#include 
    
     #include "gearc3d.h"CCreateEnt::CCreateEnt(void){}CCreateEnt::~CCreateEnt(void){}AcDbObjectId CCreateEnt::CreateLine(AcGePoint3d ptStart,AcGePoint3d ptEnd){	// 在内存上创建一个新的AcDbLine对象	//AcGePoint3d ptStart(0, 0, 0);	//AcGePoint3d ptEnd(100, 100, 0);	AcDbLine *pLine = new AcDbLine(ptStart, ptEnd);		AcDbObjectId lineId;	lineId = CCreateEnt::PostToModelSpace(pLine);	return lineId;}AcDbObjectId CCreateEnt::PostToModelSpace(AcDbEntity* pEnt){	// 获得指向块表的指针	AcDbBlockTable *pBlockTable = NULL;	//workingDatabase()能够获得一个指向当前活动的图形数据库的指针，	acdbHostApplicationServices()->workingDatabase()->getBlockTable(pBlockTable, AcDb::kForRead);	// 获得指向特定的块表记录（模型空间）的指针	AcDbBlockTableRecord *pBlockTableRecord NULL;	pBlockTable->getAt(ACDB_MODEL_SPACE, pBlockTableRecord,AcDb::kForWrite);	// 将AcDbLine类的对象添加到块表记录中	AcDbObjectId entId;	pBlockTableRecord->appendAcDbEntity(entId, pEnt); 	// 关闭图形数据库的各种对象	pBlockTable->close();	pBlockTableRecord->close();	pEnt->close(); 	return entId;}AcDbObjectId CCreateEnt::CreateCircle(AcGePoint3d ptCenter, AcGeVector3d vec, double radius){	AcDbCircle *pCircle = new AcDbCircle(ptCenter, vec, radius);	// 将实体添加到图形数据库	AcDbObjectId circleId;	circleId = CCreateEnt::PostToModelSpace(pCircle);	return circleId;}AcDbObjectId CCreateEnt::CreateCircle(AcGePoint3d ptCenter, double radius){	AcGeVector3d vec(0, 0, 1);	return CCreateEnt::CreateCircle(ptCenter, vec, radius);}AcDbObjectId CCreateEnt::CreateCircle(AcGePoint2d pt1, AcGePoint2d pt2){ 	// 计算圆心和半径	AcGePoint2d pt = CCalculation::MiddlePoint(pt1, pt2);	AcGePoint3d ptCenter(pt[X], pt[Y], 0); // 圆心	double radius = pt1.distanceTo(pt2) / 2;//distanceTo 函数用于计算两点之间的距离，也就是半径		// 创建圆	return CCreateEnt::CreateCircle(ptCenter, radius);}AcDbObjectId CCreateEnt::CreateCircle(AcGePoint2d pt1, AcGePoint2d pt2,AcGePoint2d pt3){	/*	// 使用数学方法	double xysm, xyse, xy;	AcGePoint3d ptCenter;	double radius; 	xy = pow(pt1[X], 2) + pow(pt1[Y], 2);	xyse = xy - pow(pt3[X], 2) - pow(pt3[Y], 2);	xysm = xy - pow(pt2[X], 2) - pow(pt2[Y], 2);	xy = (pt1[X] - pt2[X]) * (pt1[Y] - pt3[Y]) - (pt1[X] - pt3[X]) * (pt1[Y] - pt2[Y]);	// 判断参数有效性	if (fabs(xy) < 0.000001)	{		AfxMessageBox(_T("所输入的参数无法创建圆形！"));		return 0;	}	// 获得圆心和半径	ptCenter[X] = (xysm * (pt1[Y] - pt3[Y]) - xyse * (pt1[Y] - pt2[Y])) / (2 * xy);	ptCenter[Y] = (xyse * (pt1[X] - pt2[X]) - xysm * (pt1[X] - pt3[X])) / (2 * xy);	ptCenter[Z] = 0;	radius = sqrt((pt1[X] - ptCenter[X]) * (pt1[X] - ptCenter[X]) + (pt1[Y] - ptCenter[Y]) * (pt1[Y] - ptCenter[Y]));	if (radius < 0.000001)	{		AfxMessageBox(_T("半径过小！"));		return 0;	}	return CCreateEnt::CreateCircle(ptCenter, radius);*/	// 使用几何类	AcGeCircArc2d geArc(pt1, pt2, pt3);	AcGePoint3d ptCenter(geArc.center().x, geArc.center().y, 0);	return CCreateEnt::CreateCircle(ptCenter, geArc.radius());	}AcDbObjectId CCreateEnt::CreateArc(AcGePoint3d ptCenter, AcGeVector3d vec, double radius, double startAngle, double endAngle){	AcDbObjectId arcId;	AcDbArc *pArc = new AcDbArc(ptCenter, vec, radius, startAngle, endAngle);	arcId = CCreateEnt::PostToModelSpace(pArc);	return arcId;}AcDbObjectId CCreateEnt::CreateArc(AcGePoint2d ptCenter, double radius, double startAngle, double endAngle){	AcGeVector3d vec(0, 0, 1);	return CCreateEnt::CreateArc(CCalculation::Pt2dTo3d(ptCenter),vec, radius, startAngle, endAngle);}AcDbObjectId CCreateEnt::CreateArc(AcGePoint2d ptStart, AcGePoint2d ptOnArc, AcGePoint2d ptEnd){	// 使用几何类获得圆心、半径	AcGeCircArc2d geArc(ptStart, ptOnArc, ptEnd);	AcGePoint2d ptCenter = geArc.center();	double radius = geArc.radius();	// 计算起始和终止角度	AcGeVector2d vecStart(ptStart.x - ptCenter.x, ptStart.y - ptCenter.y);	AcGeVector2d vecEnd(ptEnd.x - ptCenter.x, ptEnd.y - ptCenter.y);	double startAngle = vecStart.angle();	double endAngle = vecEnd.angle();	return CCreateEnt::CreateArc(ptCenter, radius, startAngle, endAngle);}AcDbObjectId CCreateEnt::CreateArcSCE(AcGePoint2d ptStart, AcGePoint2d ptCenter, AcGePoint2d ptEnd){	// 计算半径	double radius = ptCenter.distanceTo(ptStart);	// 计算起、终点角度	AcGeVector2d vecStart(ptStart.x - ptCenter.x, ptStart.y - ptCenter.y);	AcGeVector2d vecEnd(ptEnd.x - ptCenter.x, ptEnd.y - ptCenter.y);	double startAngle = vecStart.angle();	double endAngle = vecEnd.angle();	// 创建圆弧	return CCreateEnt::CreateArc(ptCenter, radius, startAngle, endAngle);}AcDbObjectId CCreateEnt::CreateArc(AcGePoint2d ptStart, AcGePoint2d ptCenter, double angle){	// 计算半径	double radius = ptCenter.distanceTo(ptStart);	// 计算起、终点角度	AcGeVector2d vecStart(ptStart.x - ptCenter.x, ptStart.y - ptCenter.y);	double startAngle = vecStart.angle();	double endAngle = startAngle + angle;	// 创建圆弧	return CCreateEnt::CreateArc(ptCenter, radius, startAngle, endAngle);}
    

最后，创建AutoCAD命令，达到在AutoCAD命令行中输入命令，布局窗口看到我们的大斧头的目的：

**********acrxEntryPoint.cpp*******************static void HHLCreateEntsLine(void)	{		AcGePoint3d ptStart(0, 100, 0);		AcGePoint3d ptEnd(0, -100, 0);		AcDbObjectId lineId;		lineId = CCreateEnt::CreateLine(ptStart, ptEnd);		CModifyEnt::ChangeColor(lineId, 1);		ptStart.set(-10, 100, 0);		ptEnd.set(-10, -100, 0);		lineId = CCreateEnt::CreateLine(ptStart, ptEnd);		CModifyEnt::ChangeColor(lineId, 1);		CModifyEnt::ChangeLayer(lineId, _T("虚线"));		CModifyEnt::ChangeLinetype(lineId, _T("中心线"));	}	static void HHLCreateEntsCircle(void)	{		// “圆心、半径”法创建一个圆		AcGePoint3d ptCenter(50, 50, 0);		CCreateEnt::CreateCircle(ptCenter, 5);		// 两点法创建一个圆		AcGePoint2d pt1(70, 100);		AcGePoint2d pt2(130, 100);		//CCreateEnt::CreateCircle(pt1, pt2);		// 三点法创建一个圆		pt1.set(60, 100);		pt2.set(140, 100);		AcGePoint2d pt3(100, 60);		//CCreateEnt::CreateCircle(pt1, pt2, pt3);	}	static void HHLCreateEntsArc(void)	{		// 创建位于XOY平面上的圆弧		AcGePoint2d ptCenter(50, -50);		CCreateEnt::CreateArc(ptCenter, 100 * sqrt( (double)2 ) / 2, 1 * CCalculation::PI() / 4, 3 * CCalculation::PI() / 4);				// 三点法创建圆弧		AcGePoint2d ptStart(100, 0);		AcGePoint2d ptOnArc(120, 50);		AcGePoint2d ptEnd(100, 100);		CCreateEnt::CreateArc(ptStart, ptOnArc, ptEnd);				// “起点、圆心、终点”创建圆弧		ptStart.set(100, 100);		ptCenter.set(50, 150);		ptEnd.set(0, 100);		CCreateEnt::CreateArcSCE(ptEnd , ptCenter, ptStart);				// “起点、圆心、圆弧角度”创建圆弧		ptStart.set(0, 0);		ptCenter.set(-50, 50);		CCreateEnt::CreateArc(ptStart, ptCenter, CCalculation::PI() / 2);	}ACED_ARXCOMMAND_ENTRY_AUTO(CCreateEntsApp, HHL, CreateEntsLine, CreateLine, ACRX_CMD_TRANSPARENT, NULL)ACED_ARXCOMMAND_ENTRY_AUTO(CCreateEntsApp, HHL, CreateEntsCircle, CreateCircle, ACRX_CMD_TRANSPARENT, NULL)ACED_ARXCOMMAND_ENTRY_AUTO(CCreateEntsApp, HHL, CreateEntsArc, CreateArc, ACRX_CMD_TRANSPARENT, NULL)

注意：最后这部分代码是加在现有cpp里的，该cpp为程序的主入口