I wonder if I can change the properties (let's say line type) in just a part of a line or object. For instance, a circle over a part of another circle. A part of the circle beneath would be hidden. So I would like to change the property of the circle behind  the other, but just the part which is hidden of course.Any help appreciated Richy

First copy the circles to other place and change the copied circles property to dashed line. Then do trimming for unecessary part as you needed. Trim also the hidden part of the original one. Move back the trimmed dashed circles to original one using appropriate osnap (ie: center). That's what I would do.
 
hth,
Rman

You can [CMD]BREAK[/CMD] the circle at two points, which terminates visible/hidden part of circle. If you want the circle to cohere, make it the group.

[QUOTE=gato richy]I wonder if I can change the properties (let's say line type) in just a part of a line or object. For instance, a circle over a part of another circle. A part of the circle beneath would be hidden. So I would like to change the property of the circle behind  the other, but just the part which is hidden of course.Any help appreciated Richy
[/QUOTE]What are you attempting to do?  you could make the circle that is "on top" a clear item, so that it obscures the part of the circle below it, that it covers..  or are you attempting to do something else??Wipeout?  Although only with a Polyline...which version of ACAD are you using?

Thanks a lot Roman, Kackac and Ross.I think Roman got the point. I thought there was a command like BREAK (like Kadkad said) as to do this kind of operations, making the op. faster.My cad is 2007Im makin a 2D draw which has a lot of hidden parts of a same line, so it is tedious to Break the lines and make a hidden one among them.If you hava another suggestion please, fell free to post it, I'll appreciate all your help.Richy

[QUOTE=Kackac]You can [CMD]BREAK[/CMD] the circle at two points, which terminates visible/hidden part of circle. If you want the circle to cohere, make it the group.[/QUOTE]I thought 'bout BREAK but in case of circles, it gives you problems. One is that you lose an arc and have to draw it again, tedious when there're many.Thanks

[QUOTE=Kackac]You can [CMD]BREAK[/CMD] the circle at two points, which terminates visible/hidden part of circle. If you want the circle to cohere, make it the group.[/QUOTE]I did just what you said, seems fine when there are no many circles one over another. But with 4 (as I tried today) you lose which line is hidden and which is not.I guess it has to like this, since I thought there existed a particular function to do this.Thanks

I'm not sure I understand you well, my english isn't good, but...[QUOTE=gato richy]I thought 'bout BREAK but in case of circles, it
gives you problems. One is that you lose an arc and have to draw it
again, tedious when there're many.[/QUOTE]If you lose a part (rest) of circle, it depend on the direction you select the 1st and 2nd point of break - clockwise or counterclockwise. Or if you mean you lose the part of circle between 1st and 2nd point, this lisp could help you, it break an entity at point, but take care of draw order, it breaks the upper one... Run it typing BP into a command line after apload it into the autocad (If you don't know how to upload it to autocad, ask, I'll help you)uploads/20081128_224944_break_point.lsp[QUOTE=gato richy]I did just what you said, seems fine when there are
no many circles one over another. But with 4 (as I tried today) you
lose which line is hidden and which is not.[/QUOTE]I'm sorry, bud I don't understand it - why do you have 4 circles one over another?
Kackac2008-11-28 23:29:43

Command are upload but not working

Can you specify, what doesn't work, please? What AutoCAD tell you after typing command BP for this lisp?

Hello
if your circles are the same allways you can make a block with them and in this block you can make the linetype of a part to be allways in a way indifferent of the layer you use.