【转帖】objectarx&dummies习题（一）答案
 

objectarx&dummies习题（一）答案
objectarx&dummies习题（一）答案
lab 1 - solved
hello,
hope you did solve this lab. i will present my solution now but this doesn't mean that this is the best or the only way to go.
after have created the project and added the two commands as the lab instructions said, open the acrxentrypoint.cpp file, move your cursor into carxlab1app class and add the following code:
static acdbobjectid addtomodelspace(acdbentity* pent) {
acdbobjectid entid = acdbobjectid::knull;
// get block table
acdbblocktable* pblocktable = null;
acdbhostapplicationservices()->workingdatabase()
->getblocktable(pblocktable,acdb::kforread);
// get block table record (model space)
if (pblocktable) {
acdbblocktablerecord* pbtr = null;
// open modelspace (for write)
pblocktable->getat(acdb_model_space,
pbtr,acdb::kforwrite);
if (pbtr) {
// add entity and get its objectid
pbtr->appendacdbentity(entid,pent);
// close btr
pbtr->close();
}
// close block table
pblocktable->close();
}
return entid;
}
static void arxlab1_cents(void) {
// first, let's create the circle
acgepoint3d cenpt(0,0,0);
acdbcircle* pcirc = new acdbcircle(cenpt,
acgevector3d::kzaxis,10.0);
// add the circle to database and close it
addtomodelspace(pcirc);
pcirc->close();
// now, let's create the line
acgepoint3d startpt(0,0,0);
acgepoint3d endpt(10,10,0);
acdbline* pline = new acdbline(startpt,endpt);
// add the line to database and close it
addtomodelspace(pline);
pline->close();
}
static void arxlab1_chents(void) {
ads_name en;
ads_point pt;
// prompt for selection
if (acedentsel("\nselect an entity: ",
en, pt) == rtnorm) {
acdbobjectid eid = acdbobjectid::knull;
// get the objectid from ads_name
acdbgetobjectid(eid, en);
acdbentity* pent = null;
// open entity (for write) to chance its color
if (acdbopenobject((acdbobject*&)pent,
eid,acdb::kforwrite) == acad::eok) {
pent->setcolorindex(1);
// close the entity!
pent->close();
}
}
else acutprintf("\ncommand aborted.");
}
the first function, called addtomodelspace() is a generic utility function which adds an arbitrary entity to modelspace and return its objectid. following this function you will find two functions that were linked with cents and chents commands.
all 3 funtions are placed into your application class. pay attention to the code flow and be careful to not forget any braces or close() methods.
英文真棒，请教老大怎样学好英文呢