Using REGION and SUBTRACT commands to clip intersecting viewports

[jaredmccullough]

I have a question in regards to using the REGION and SUBTRACT command to clip viewports. I have a rectangle that serves as the overall viewport for the paperspace. Within this viewport are multiple smaller circles which serve as viewports. I have read of a technique using REGION and declaring the larger of the viewports a region and each of the smaller ones separate regions then using the SUBTRACT the command to eliminate the overlap. Then making smaller circles within the subtracted space.

 

I am able to delcare the smaller viewports as REGIONs but the larger one will not. Anyone have an idea of why this might be.

 

Also is there any other concerns I should worry about will using this technique?

[ReMark]

Can you post a link to the description of this technique? I'd like to read it myself. Thank you.

[nestly]

Sounds like this Autocad Knowledge Base article

 

Creating a circular viewport completely contained within a larger rectangular viewport

 

The problem may be if the rectangle has already been turned into a viewport. The technique above assumes starting with just a rectangle, and 2 circles in Paperspace. For multiple circular viewports, SUBTRACT all the circular regions from the rectangular region, then convert each remaining circular region into it's own viewport.

Edited July 31, 2013 by nestly

[jaredmccullough]

Remark here is an older post I made with the original concern (read Rkents post): http://www.cadtutor.net/forum/showthread.php?71867-Intersecting-Viewports-Issue

 

Nestly so your saying if I have to start the rectangular viewport over and deem it a region before I turn it into a viewport correct?

[JD Mather]

....

Nestly so your saying if I have to start the rectangular viewport ....

 

I might be missing something because I didn't read through all of this.

But what happens if you don't start with ANY viewport(s).

Create and trim geometry to whatever shape you want your viewport(s).

PE j to create a closed boundary.

Convert the closed boundary (whatever shape it forms) to viewport.

 

OK, now I have read the problem statement.

My initial thought was to delete this response - but I think I will leave it here as there might be something useful to someone.

[nestly]

 

Nestly so your saying if I have to start the rectangular viewport over and deem it a region before I turn it into a viewport correct?

 

To put "holes" in an existing viewport:

 

In Paperspace, create new rectangle (closed polyline) the same size/shape as the existing viewport

Add add circles (or closed polylines) where you want the "holes" to be

Use REGION command to turn all the new objects into regions (use SelectionCycling) to be sure you're selecting the "new" objects)

Use SUBTRACT to remove the smaller regions from the larger one. (use Selection Cycling to assist selecting the right objects)

You should now have only one "region"

Using VPCLIP, select the existing Viewport first, then select the region as the clipping object.

Now your original VP has some "holes" through it.

Depending on your DELOBJ settings, the objects (circles) you used to create the smaller regions may or may not still be there, If they are, use MVIEW > Object to turn them into viewports (again, use SelectionCycling to make sure you're selecting the right objects). If the "circles" were deleted when the regions were created, recreate them and turn them into viewports.

[jaredmccullough]

Nestly

 

I did partially as you stated. I made a rectangle the same size as the "Larger Viewport", made the mulitple smaller viewports, used region and subtract commands. It worked good but I had a few questions concerns:

 

1.) The smaller circles seemed to become part of the "Larger" rectangle viewport making a shape. I am assuming this was the intent but you had mentioned that depending on the DELOBJ settings the circles will be there. What exactly would I need these settings to be on to have the circles stay there?

 

2.) I deleted the original larger viewport noting the scale so I can recreate it in the new "rectangle" viewport because I didnt quite understand the viewport clipping because it was not working for me. I made the new rectangles viewports and put them to the same scale that the old ones were. Do you feel this is an appropriate method or should I be trying to VPCLIP the original?

[nestly]

Nestly

1.) The smaller circles seemed to become part of the "Larger" rectangle viewport making a shape. I am assuming this was the intent but you had mentioned that depending on the DELOBJ settings the circles will be there. What exactly would I need these settings to be on to have the circles stay there?

 

That's the expected behavior if DELOBJ is set to delete the defining Geometry, but whether the circle is automatically deleted upon creation of the Region doesn't really matter.... just redraw it after clipping the Region from the original VP.

 

2.) I deleted the original larger viewport noting the scale so I can recreate it in the new "rectangle" viewport because I didnt quite understand the viewport clipping because it was not working for me. I made the new rectangles viewports and put them to the same scale that the old ones were. Do you feel this is an appropriate method or should I be trying to VPCLIP the original?

 

Yeah, you need the original rectangular viewport. It will be modified to include the "holes" after the Region is "clipped" from it.

 

I made a demo with only one circular viewport, but you can have as many as you need. -->

 

If you still have trouble, upload a sample drawing with a rectangular VP the size you need, and "circles" where ever you want them. (the "holes" don't have to be circles, then can be any shape you can turn into a Region)

 

Also, when completed, the Viewports (and geometry associated with the VPs), should be placed on a "Viewports" layer.

[rkent]

I use a different set of steps to get there.

 

No viewports exist.

Draw a rectangle,

draw a circle,

make them regions,

subtract the circle from the rectangle,

use mview, object, select the region,

adjust the vp scale.

Draw a circle over the circular cutout in the region,

mview, object, select the circle,

adjust the scale in that viewport.

[nestly]

rkent, that's pretty much the method described in link in post #3 and it is simpler, however without having an existing VP to show the model, how do you know where the "holes" should be placed, and how large the "holes" should be?

[rkent]

rkent, that's pretty much the method described in link in post #3 and it is simpler, however without having an existing VP to show the model, how do you know where the "holes" should be placed, and how large the "holes" should be?

 

Well, you are right, without the viewport you wouldn't know where to place the holes. I have stopped using this method because of the inability to edit the size and location of the region. I was thinking of another method using plines, etc. A continuous pline that forms a large and small rectangle(s) for the larger viewport and then a smaller rectangle for the other. Easily edited for size and location.

[nestly]

Thanks for the clarification. This is the first time I've actually put a "hole" in a VP and thought I might be missing something. I also use mainly polygonal VP's that can be grip edited. Sometimes I do put a viewport within a viewport if there's enough dead space... or use a wipeout if there's not.