Join Paul F. Aubin for an in-depth discussion in this video Understanding cutable families, part of Revit: Tips, Tricks, and Troubleshooting.
- [Instructor] In this video I want to talk about cuttable elements. So all of the categories in Revit are either cuttable or non-cuttable and the difference determines how they will display in plans and in sections. So with cuttable elements you actually get a live slice through the element at the point of the cut plane. This is either the floor plane, cut plane, or the section line. With a non-cuttable element the element will display in its entirety regardless of whether you're slicing through it or not. So what I have here on screen is two different showers and they look identical initially in the views that I have displayed here, I have a floor plan on the left and a section on the right, but they're actually quite different from one another.
And I can illustrate that fairly quickly by taking this section line and just sort of moving it forward a little bit, so that it just slices through the front of the Shower Pan on both sides. And when I do that you'll see that the shower here on the left remains unchanged, but the one here on the right is now actually slicing through the Shower Pan, versus this one over here where it is ignoring that slice and just showing you the overall graphic. So what's the difference? Let me undo that and move that section line back.
Well, first of all, let's start off with what cuttable categories are, or rather which categories are cuttable. So you can see this easily enough by just going to Visibility Graphics. So if I type V-G to get into the Visibility Graphics dialog it will list out all of the model categories and you'll be able to tell just by looking at this window which categories are cuttable and which ones aren't. Those categories that have Override buttons all the way across, those are cuttable categories, but the ones where the Cut column is grayed out, those are non-cuttable.
So, for example, Casework is cuttable, but if I come down here and I look at Furniture you can see that Furniture is not cuttable. Now if we go a little bit further down and we locate Plumping Fixtures we'll see that Plumbing Fixtures are not cuttable. So this explains why at least the shower on the left is not showing in cut, but doesn't really explain what's going on with the shower on the right. Well, let's investigate a little bit further. It turns out that both of these elements are Plumbing Fixtures, so here's the shower on the left, it's a Plumbing Fixture, here's the shower on the right, it's also a Plumbing Fixture.
So how did I get one of them to behave like a cuttable element and the other is behaving in its default manner? Well, let's start with the default one, let's start with the one here on the left and select that family and open it up with Edit Family. Now the way that I built both of these showers was to create the components within them as nested families. So if you look at the Shower Pan here you can see that this is another Plumbing Fixture for the Shower Pan.
And at first assumption might be that that would be the correct way to go, until you start to consider things like the cuttability of the object you may be tempted to just create it as a Plumbing Fixture. The Shower Head is also a Plumbing Fixture, which again, seems perfectly logical initially when we're considering that we're trying to create a shower and that seems like, a Plumbing Fixture seems like the right category. So if you don't mind that the Shower Pan is not showing slice through then maybe this is perfectly fine the way that I've built it here.
Now I'm going to close out of here and talk about one other reason why you might not be satisfied with the way that that one is built. Notice that I have these other two sections here cutting at odd little angles. Well, cuttability isn't just when you happen to be looking at it nice and orthogonally. If I take this section here cutting through the non-cuttable version of the shower, open that one up, notice that it still continues to display the entire shower. More importantly, it's actually showing the fixtures of the shower, even though they're actually behind the cut plane.
So we're cutting well in front of those, if we kind of drop this down and take a look here, we are cutting well in front of that Shower Head and we're cutting here looking in the opposite direction and yet they still display. So that's the other reason that you might not be satisfied with just using the standard behavior of the non-cuttable Plumbing Fixture category. Now let's compare that to this section over here. When I open that one up and take a look this one is behaving like a cuttable element.
Notice that it's only showing me the little corner of the Shower Pan that I happen to be slicing through at the moment and it's not showing me anything else. It's being quite literal in fact and that may be too extreme in the other direction, but it's one or the other behaviors that you're going to get. So how did I make this one cuttable? So let's select this one and do Edit Family to talk about that. We've got two nested families again, so this is a family and this is a family. Now I'll talk about this in a moment.
This one is still a Plumbing Fixture, but this one down here, there's two things that I did to make it cuttable. The first is make sure that the nested component is a cuttable category. So if you think back to the Visibility Graphics dialog that we were in a moment ago, if you scroll down through the list and look for cuttable categories you'll find that Generic Model is one of the cuttable categories. So in this case I decided that it was okay for the Shower Pan to be a Generic Model nested inside that Plumbing Fixture, because the parent family is still a Plumbing Fixture and I'll be able to turn on and off Plumbing Fixtures and do other Plumbing Fixture like things to it, but the Pan itself will take its cuttable behavior forward into the parent family, as long as I do one other thing.
And that one other thing is to take this Generic Model family, let's edit it, and make sure that it's set as a Shared family. Now this is very important. If it's not set as a Shared family, if I were to uncheck that and load it all the way back through it would no longer cut through the Shower Pan anymore, because that Generic Model behavior would stop at the level of the Plumbing Fixture, but when you make it a Shared family you're taking that behavior and pushing it all the way through to the project.
That's what Shared means, you're sharing the behavior of that family all the way through. So you can tab in and select it, you can schedule it on schedules, you can make sure that that cuttable behavior comes forward. You get all of those benefits when you do a Shared family. So that's the trick to making the Shower Pan cuttable. Now if I select the Plumbing Fixtures and edit that family they are also set to Shared. And that's important as well to help get what we want, but what we want here is a little bit different than what we wanted with the Shower Pan.
What I wanted with the Shower Pan was to be able to slice through it and have it actually show a live cut through the Shower Pan. But I don't want to slice through the Shower Head, I don't want to see just part of the Shower Head when I'm cutting through it. I either want to see the Shower Head or not, but I want it to display more intelligently based on whether I'm looking at it or whether it's near by the cut. So let me show you a couple diagrams to help illustrate what's really going on here. So our original shower family looks something like this. If you leave it in the Plumbing Fixture category then what happens is the way that Revit determines if it will be visible or not is by looking at the bounding box of the entire object.
So if you imagine a box surrounding the entire object then if any part of this box intersects the cut plane it displays the entire object. So that's why even though we were slicing through a little corner we were still seeing the stuff behind, because if it hits the box it shows the whole thing. Now contrast that to the behavior when you nest in Shared families instead. When you nest in Shared families now instead of the overall bounding box of the main object taking precedence what you actually get is a separate bounding box for each Shared family.
So here I'm highlighting the bounding box that we get for the Shower Pan and because it's also a cuttable category not only does that bounding box dictate when to display that element, but it will also do a live cut through that element because it's Generic Model and it's cuttable. Now contrast that to the Fixtures and they have a much smaller bounding box now, which means that they will only display if the section cut hits the smaller bounding box, but because the subcategory is still Plumbing Fixture it follows the rules of a non-cuttable family, meaning it will either display it or it won't.
So if your section cut even nicks a little corner of this bounding box it displays the entire fixture, but if it misses that bounding box then it doesn't display it at all. And this is why it's so much easier to control what you're going to get when you have that Shared version of the Shower Head. So if we go back to this example here, if I open up this section I'm only seeing the little corner of that Shower Head that I'm slicing through, but if I start to move this section head and let's move it in a little bit.
You see, I'm still seeing just the Shower Pan. Notice I'm not getting the Shower Head at all yet until I get close enough to it that it starts to intersect the bounding box of the Shower Head and then it displays the whole thing. So, again, the nested component of the Shower Head is a non-cuttable category, so it either displays or it doesn't. The nested component of the Shower Pan is a cuttable category, so not only does it display or not, but it also displays live in cut, it displays what actually is being sliced through, as apposed to just showing it or not showing it.
So this is how you can mix and match the behaviors and when you understand what the behavior of each category is then toggling on that Shared checkbox gives you the flexibility to be able to decide which behaviors you want your overall family to have and kind of build those in by nesting in Shared components of appropriate categories to give you those various behaviors.
NOTE: The exercise files for this course can only be opened in the most recent version of Revit (Revit 2017).
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