08.09.12

1.Handle is saved with the graphics,but not ID or the pointer to the object.

The specifically pointer die while closing the graphics.So does the ID of the object while saving the graphics.

2.An object can only be deleted before it is put into  database.Because database is read-only.

3.Handle->Pointer

AcDbObject* pObject;

AcDbHandle handle;

pObject->getAcDbHandle(handle);

 

Study on database and data structure is a big problem.

4.radio ratio(you will know it when creating an ellipse with AcDbEllipse())

=short Axis/long Axis ,so it is smaller than 1.

5.AcDbEllipse(const AcGePoint3d& center,...,double startAngle=0,double endAngle=6.283185);

This is the function used in creating an ellipse.

If the last two parameter is not the default value,you will get an ellipse arc.

fabs() can make you get the absolute value of a number.

6.assert();

This function is used to assert a number or an expression or a variable is right or not .

If not ,it has a popup error message box warning you've done wrongly.

7.const AcGePoint3d& center:=AcGePoint3d center.

Still not clear in this problem.

 

8.AcGePoint3d::kOrigin retruns the point (0,0,0);