LT Unlimited

Deal with Gaps in Hatch Boundaries

In AutoCAD LT 2009 and earlier, when you're trying to hatch an area by picking points, it can be so frustrating to see the "valid boundary not found" error message. You had to go hunting around to see if you could find the gap, or increase your Hatch Gap Tolerance, which would create the hatch but make it non-associative.

In AutoCAD LT 2010, both those options have been significantly improved. (It still can't fix gaps in hatch boundaries for you, unfortunately.)

Using the Hatch Gap Tolerance (hiding in the expanded portion of the Hatch dialog) still results in a non-associative hatch. But, as I showed you in a previous post, this is no longer much of a problem when it comes to modifying the hatch later.

If you'd rather fix the gap than work around it, though, LT 2010 can help. When you pick a point that's not in an enclosed area, you now get a much more helpful message:

When you click Close, you can now see exactly where the problem is:

The little red circles go away after a Redraw or Regen.

No more hunting for tiny errors in a hatch boundary! (Although it can only find one or two gaps at a time, so if you have a very broken boundary you may have to run it a few times to find all the holes.)

Edit Non-Associative Hatch Objects

AutoCAD LT 2010 is stuffed full of what I like to call "little big" features -- things that don't take very long to explain or learn, but which will make enormous differences in your day-to-day work.

One of these "little" features is the ability to edit the boundary of a non-associative hatch object.

Let's say that I have a hatch object that for whatever reason isn't filling its boundary the way it should:

Until now, if you selected that hatch object, all you got was one (unhelpful) grip:

And your only choice was to erase the hatch and start over. Let's see what happens when I select that same hatch in LT 2010:
 
Look at all those grips! The large square ones can be used to move corners, while the rectangular ones in the middle of each side can be used to add vertices or convert sides between line and arcs. Check it out:

Now, that's not getting as much attention as the PDF improvements (or as parametrics and freeform over on the AutoCAD side), but it's still an impressive time-saver!

Set Object Snaps to Ignore Hatches

Object snaps are wonderful things, but occasionally you don't actually want to use them. For example, intersecting lines in a hatch pattern probably aren't part of your design, and you'd rather not have them appear as an option when you're looking for intersections.

Fortunately, removing hatches as object snap targets is simple. Just go to the Options dialog, Drafting tab, and check the box marked "Ignore Hatch Objects" under "Object Snap Options". (You can also use the system variable OSOPTIONS.)

Select Hatch and Boundary

Last in the series on unexpected selection behavior is Associative Hatch -- and it's probably not the kind of associative you're thinking of.

Typically, when we hear that a hatch is associative, we understand that to mean that when the boundary of the hatch is modified, the hatch will update to fill the new area. In the context of selection behaviors, though, it means that when the hatch is selected, its boundary is too.

Like the previous two settings, Associative Hatch is also on the Selection tab of the Options dialog. (It's also the PICKSTYLE variable.) The effects of checking this box are noticed most often in trying to delete a hatch. You select the hatch, press Delete, and suddenly the bounding object has been deleted too. If that's not what you wanted, all you need to do is undo, then hop into the Options dialog and put the setting back to normal.

Set Hatch Draw Order

Since AutoCAD LT 2005, you've had the ability to set the draw order of hatches as they're created. In the Options section of the Hatch dialog, you can choose one of the following:

• Do not assign
• Send to back
• Bring to front
• Send behind boundary
• Bring in front of boundary

The default is "Send behind boundary", which means that the hatch is placed under its boundary object but over any other existing objects.

This setting is important for both viewing and plotting -- objects that are "under" other objects are hidden behind them on the screen and during plotting, if your plotter is set to "overwrite lines". Overwriting means that if an object with a thin lineweight is drawn over one with a thicker lineweight, only the thinner line will be printed. Depending on your industry and the final effect you want, this can be a good or a bad setting.

If you have your plotter set up to use "merge lines" this setting doesn't matter as much -- thicker lines win all the time. Even so, I like to keep the "send behind boundary" option set, so that it's easy to see the hatch boundaries on screen.

Recreate Hatch Boundary -- Follow Up

I posted on this topic awhile back, but thanks to a comment and some discussion board conversations, i thought it deserved a follow-up.

In versions prior to LT 2009, the hatch's creation method determines what kind of polyline boundary you're going to get. If you used the "pick point" option, you'll get a closed polyline when you recreate the boundary. However, if you used the "select object" method, the re-created boundary will be lots of separate polylines.

This has been fixed in LT 2009, so that no matter how the hatch was created, the new boundary will be a closed polyline.

Follow-up: Trim Hatches

After I posted about trimming hatches, terbgrave asked, "Why does this only work some of the time when you are trying to trim solid hatches? and it works sometimes when you pick in the perfect spot but nowhere else on the hatch?"

I agree, solid hatches can be a bit temperamental when you try to select them. My best guess would be that it's because solid hatches don't have "lines" or "points" the way other patterns do. You may have to be a little patient & hover your cursor over different spots until you get the hatch, but it will eventually show up.

I also just received a comment asking about this feature in previous versions of AutoCAD, but I believe it wasn't introduced until LT 2007.

Retroactively Create Separate Hatches

Say you've hatched a bunch of objects, and only afterwards realized that you meant to have the "create separate hatches" option checked. Is your only choice now to delete them and start over? Nope -- this option can be applied retroactively through the Hatch Edit command.

Simply double-click on the hatch, check the "create separate hatches" option, and click OK. All hatch "islands", whether defined by "pick points" or "select objects", will become separate entities ready to be further edited at will.

Recreate Hatch Boundary

A hatch that has lost its boundary (and has therefore become non-associative) is not necessarily a lost cause. The new “Recreate Boundary” option in the Hatch Edit dialog saves you from having to delete the hatch and start over. Simply double-click on the troublesome hatch and select “Recreate Boundary”.

You’ll be asked if you want the new boundary to be a region or a polyline. Polylines are more flexible than regions, but the resulting boundary will be lots of separate polylines. Which works, but unfortunately, joining the polylines together into a single object disassociates the hatch again. (Oh well, you can’t have it all.)

Then you’ll be asked if you want to associate the hatch with the new boundary. Considering that the most obvious reason you would want the boundary back is to edit it, you’ll probably want to say yes. Click OK to exit Hatch Edit.

Add Object to Hatch

Let's say you've hatched an area of your drawing, but now you need to add a note, symbol, or some other thing in the middle of it -- and you don't want the hatch to obscure your new object.

Rather than erasing the hatch and starting over, simply double-click on it to launch the HATCHEDIT command (also under Modify-->Object-->Hatch). From the options on the right, select "Add Objects" and pick to select your objects. Click OK, and your hatch now follows around the outside of your text/block/whatever.