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 <math.h>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 <math.h>
#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