AutoCAD Civil 3D

[#1]

Hello

i need a help recently i try to practice on SAC and i have problem i want to know how to add shape only for the exterior area 

i want only the area in yellow color and the red one be empty

Thank you

[#2]

I don't think it's possible. I was trying to use Aux links to try and define it without success.

It would be nice to be able to subtract one shape from another. You can define the inner shape and overall shape, but not the difference. S3=S2-S1

Maybe Peter Or Kati might has some suggestions.

[#3]

You need 2 links, one on top of the other connecting the inside set of links to the outside set of links to make the "donut" one continuous set of links instead of two sets of links. 

Hope this makes sense without a graphic. If it doesn't let me know and I can sketch up something for you. 

[#4]

Thanks Kati,

In this case I created L9 & L10 to get from the inner to the outer boundary. I'm not sure the original poster is going to want those links to show. Is there any way in SAC to not show them? I tried Auxiliary links already.

[#5]

Yes, sadly you will need them to be links and not auxiliary links. I typically just put them in a central location to make them look like they are 'supposed' to be there. 

[#6]

You should be able to apply different codes to those links than the rest of the links in the sub.  That way you can use code sets in C3D to make them not display.