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- View Offline
- Understanding points, edges, and polygons
- Working with the Knife, Extrude, and Bridge tools
- Connecting splines
- Rounding corners
- Extruding paths from Illustrator
- Reviewing the polygon and spline modeling workflow
- Working with NURBs
Skill Level Beginner
When working in Points, Edges, and Polygons, the Extrude tool allows you to create extrusions or movement in the polygons as your object. Now, let's see what that means. I'm going to do my same trick here, I'll add a cube and make it editable. This time I'm going to travel into Polygon mode. Now, I'm going to use the Selection tool. I'll just hit the Spacebar to grab the Selection tool, and I'll grab a single side of the polygon. When I do that, I right-click in the menu and I have all these options available to me now. The Extrude option is this guy right here.
I'll select that, and with the Extrude tool active, if I click and drag any place that's not on one of these handles, it's very important, don't click on the handles, click away from the handles. I'll click and drag. When I do that, I'm now extruding. I'm adding a layer of definition to this object in a way that's different than the Knife tool. Each time I click and drag, I make a new extrusion. If I click once, I deselect it. Now, let's go back and undo that for a second, and I will undo to get back all the way to the default cube.
Let's switch back to the Selection tool, and grab two sides of this cube, and I'll hit the Spacebar again to get back to the Extrude tool. When I click and drag, it extrudes these polygons in two directions. Now, what happens though if I wanted to add an extrusion that traveled around the sides where these polygons were merged together? That's where something called the Maximum Angle comes in. I'm going to undo that for a second. You notice over here in the Extrude tool, let's raise that up a bit, the Maximum Angle is set for 89. That means anything less than 89 degrees, CINEMA 4D is going to treat that as two extrusions.
And what it's referring to is the angle between the polygons, the angle from this polygon to this polygon. And I know because this is a cube it's exactly 90 degrees. So, because the Max Angle is set to 89 degrees, when I click and drag, it's going to treat these as two separate polygons. Now, if I change the Maximum Angle from 89 to 91, now it's just one degree more, I know that, that 91 is more than this angle here. Watch what happens when I click and drag. You can see that it extrudes that outward creating this arrangement of polygons on the top here, and that is a really important behavior.
There's going to be times where you want to make sure that you extrude around corners and that allows you to do it. There is one more really important option with the Extrude tool, and that's Preserve Groups. Let's see how that works. I'm going to close this document up, Command or Ctrl+W and don't bother saving it. Let's get a sphere this time. Let's make that sphere editable by clicking on the Make Editable option, and let's go into Polygon mode again. I'm going to zoom in a bit. Now, I'm going to grab just a few polygons on the front of this sphere. So, let's hit the Spacebar to get the Selection tool, and just paint a selection around.
I'll just grab a bunch of polygons here. Let's orbit around so we can see those from the side. Now, I'm going to right-click and get my Extrude tool. When I extrude outward, look what happens. It extrudes out as one solid chunk. Well, what happens if I wanted to extrude each one of those polygons individually? That's where Preserve Groups come in. That's different than the Maximum Angle. Because of the shape of the cube, the angle from polygon to polygon is extremely low. So, in order to get those polygons to separate, I have to uncheck Preserve Groups.
So let's undo; Command or Ctrl+Z and then let's uncheck Preserve Groups. And now watch what happens when I click and drag. You can see that now it extrudes each of these polygons individually creating a lot more detail, and each time I drag, I can create a new level of detail there. The next thing I want to talk about is the Create Caps option. So, once again, I'm going to close this document up, don't bother saving it. And in a new document, I'm going to create a plane this time. And a plane object is just a flat arrangement of polygons, and you can see it's laying flat on the ground plane.
I'm going to make it editable, and then go into Polygon mode. Now, the way that the Extrude tool normally behaves is that when you extrude something, it's going to leave a cavity where that extrusion happened. So, let's see what that means. I'm going to get the Selection tool, hit Spacebar, and grab an arrangement of polygons here on this plane. Let's orbit around so we can see the underside. I'm going to right-click and get the Extrude tool. And when I click and drag, I'm dragging to the right now. It's extruding outward along the polygons.
Now, you can see that it's left this cavity here, and this cavity is where the polygons used to be, and it's added this level of detail. Now, how did it know to do that? First of all, all 3D applications have something called a normal direction. The normal direction is the direction that the polygons are facing and it's along an axis that's perpendicular to the surface of the polygon. In order for me to be able to see these normals, I need to turn on an option. I'm going to go to the Options menu and go to Configure All. And under the Attribute Manager now I see the Viewport Options, and I am on the Display Section.
I'm going to turn on Normals. When I do that, I now see these little white lines extending up and those white lines tells me what direction those polygons are facing. If we look around underside, you can see that those white lines don't extend in both directions. This is the back side of the polygons, and those are the front sides of the polygons. And so, by dragging to the left, you're extruding along the normal axes. Now, the Extrude tool has a really important option. Let's right-click again and go back to the Extrude tool to get to its options. We're going to do Create Caps.
When I select Create Caps, because I had the Extrude tool still selected, it filled in the backside of those polygons. Let's undo that and redo it again. So, I'm going to undo and then I'll undo to get back to my original flat plane. When I use the Extrude tool now, I'm going to turn on Create Caps. So when I do it this time, you notice that it automatically creates polygons along the backside of that extrusion. You can see I've created depth here, but I filled in the hole on the backside automatically. There's going to be a lot of times when you want to do that. For example, let's undo one more time.
If I want to add thickness to this entire plane and have it become more of a rectangular prism, I'm going to select all the polygons and then grab the Extrude tool one more time, and I'll leave Create Caps on, and watch what happens. I'm going to click and drag to the right and I've created a rectangular prism, basically a thick plane that now has polygons on both sides. So that Create Caps option is really useful. So as you can see the Extrude tool allows you to create dimension in your objects and create unusual shapes by extruding along the normal axis. Next up, we'll take a look at the Extrude Inner tool which is a variation on that idea.