AutoCAD LT

[#1]

O.K., I'm missing something. I am trying to draw a line using osnaps tangent to two elipses. Only the second point I pick on the second ellipse ever appears to be truly tangent. The first point I pick on the first ellipse sometimes looks right but when I zoom in it really isn't tangent. Any help?

[#2]

>>O.K., I'm missing something. I am trying to draw a line using osnaps tangent to two elipses. Only the second point I pick on the second ellipse ever appears to be truly tangent. The first point I pick on the first ellipse sometimes looks right but when I zoom in it really isn't tangent. Any help?<<

If you zoom into a drawing, circles, ellipses and arcs become
facetted. You need to regen to get true circles again. This is due to
speed optimizations.

Dietmar Rudolph

President, CR/LF GmbH, http://www.crlf.de
Vice-President Europe, CADLock, Inc. http://www.cadlock.com
Webmaster, AutoCAD Developers Group Europe, http://www.adge.org
Member of the Autodesk Discussion Forum Moderator Program

Author, "Mastering AutoCAD 2000 Objects", http://www.crlf.de/Verlag/PublishingServices.html

[#3]

I checked, and do not think it is a regen issue. Try drawing two elipses, one a little larger than the other. Now turn the tangent onsap on and draw a line tangent to both elipses. When I do it, AutoCAD shows the tangent icon when picking both the first and second elipses but only the intersection with the second elipse is truly tangent. By the way, the same thing seems to happen with splines.

[#4]

>>I checked, and do not think it is a regen issue. Try drawing two elipses, one a little larger than the other. Now turn the tangent onsap on and draw a line tangent to both elipses. When I do it, AutoCAD shows the tangent icon when picking both the first and second elipses but only the intersection with the second elipse is truly tangent. By the way, the same thing seems to happen with splines.<<

Sorry, you are correct. AutoCAD does not support the 'deferred
tangent' object snap with ellipses and splines. As you can see from
the osnap marker and tooltip, using TAN with the first point of your
line will give you the tangent point *from the last used point* to the
ellipse, not the deferred tangent as with circles.

Dietmar Rudolph

President, CR/LF GmbH, http://www.crlf.de
Vice-President Europe, CADLock, Inc. http://www.cadlock.com
Webmaster, AutoCAD Developers Group Europe, http://www.adge.org
Member of the Autodesk Discussion Forum Moderator Program

Author, "Mastering AutoCAD 2000 Objects", http://www.crlf.de/Verlag/PublishingServices.html

[#5]

Thanks for confirming this. I guess I'm not going crazy after all. I am really suprised to see AutoCAD LT does not support this. Are there any workarounds besides manual construction methods? Does the full version of AutoCAD support line tangency between two ellipses or splines?

[#6]

>>Are there any workarounds besides manual construction methods? Does the full version of AutoCAD support line tangency between two ellipses or splines?<<

No ;-)

Dietmar Rudolph

President, CR/LF GmbH, http://www.crlf.de
Vice-President Europe, CADLock, Inc. http://www.cadlock.com
Webmaster, AutoCAD Developers Group Europe, http://www.adge.org
Member of the Autodesk Discussion Forum Moderator Program

Author, "Mastering AutoCAD 2000 Objects", http://www.crlf.de/Verlag/PublishingServices.html

[#7]

Thanks. Looks like an obvious enhancement request to me.