【转帖】model getgeomextents vs getextmin vs getlimmin
 

model getgeomextents vs getextmin vs getlimmin
model getgeomextents vs getextmin vs getlimmin
i want to compute the extents (in wcs) of the model layout. if i use code like this:
oddbblocktablerecordptr pmodelblock = m_pdb->getmodelspaceid().safeopenobject();
oddbobjectid layoutid = pmodelblock->getlayoutid();
oddblayoutptr playout = layoutid.safeopenobject();
odgeextents3d ext;
playout->getgeomextents(ext)==eok;
then i get a range that does not contain the ranges of the elements within the file. i don't think that any of the elements in the file have extents that intersect the range returned by getgeomextents. (i compared the returned range to the coordinates logged by odvectorizeex after i modified odvectorizeex to log the wcs coordinates like this (exgssimpledevice.cpp - exsimpleview::update)):
//
// get coordinates in wcs
//
odgematrix3d eye2screen(eyetoscreenmatrix());
odgematrix3d screen2eye(eye2screen.inverse());
odgsview* pview0 = device()->viewat(0);
seteyetooutputtransform(pview0->worldtodevicematrix().inverse() * eye2screen);
using odreadex, i dumped all of the header variables.
the range returned by calling getgeomextents on the model layout is the same as the range returned by pdb->getlimmin and pdb->getlimmax.
the range returned by pdb->getextmin and pdb->getextmax does contain the ranges of the elements within the file.
i am upgrading our application from opendwg to dwgdirect. in our old application, we used the ad_dwghdr extmin and extmax variables to determine the model range of the file and that seemed to work ok for us.
why does getgeomextents return a range that does not contain the elements within the file? is it safe to use getextmin and getextmax? if not, how do i get the total extents of all of the elements of the model?
last edited by wageoghe; 15th december 2005 at 09:12 amfff">. reason: clarify some wording.

it is not save to use pdb->getextmin() and pdb->getextmax(). these methods return the extents that are stored in dwg file; they may be incorrect.
oddblayout::getgeomextents() returns:
if(layout is a model layout)
{
return pdb->getlimmin(), pdb->getlimmax()
}
else
{
// layout is a paper layout
if(layout has viewports)
add to extents viewport extents
else
set extents to limmin,limmax layout fields
}
if(extents are still invalid)
{
// set to some paper size (landscape)
if(pdb->getmeasurement()==oddb::kmetric)
ext.set(odgepoint3d::korigin, odgepoint3d(297., 210., 0.)); // iso a4
else
ext.set(odgepoint3d::korigin, odgepoint3d( 11., 8.5, 0.)); // ansi a (8.50 x 11.00)
}
i think that example of getting the extents you need is odamfcapp zoomextents functionality.
sincerely yours,
george udov
thanks for the quick response.
i still don't understand the values returned by getgeomextents. as you can see by the code that i posted, i am getting the model layout and then calling getgeomextents. i got that code from the odamfcapp's zoomextents functionality. i observed the same thing that you stated in your post, that the model extents, as returned by getgeomextents, is the same as getlimmin, getlimmax. unfortunately, the wcs coordinates of the elements in the file do not fall inside of the extents returned by getgeomextents.
it looks like, if i were to write some code that iterated over all elements, calling getgeomextents on each one, and accumulating the total extents, the results would not be the same as the extents returned by calling getgeomextents on the model layout.
i will try to attach one file that i am using for testing.
attached files (162.0 kb, 11 views)