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In this video, we will take a look at the Extrude command and explore some of its options. We are also going to introduce to additional commands: the Offset and the Surface and Planar curves. These are two of the most useful commands and boy, they are so darn handy. We will be using them regularly in conjunction with other surfacing commands. I am going to start off by working on the eyes and mouth of our robot. To do so, I am going to jump to the Front viewport and maximize it, double-click on the label, and I want to give some thickness to these eyes before we extrude them.
So, I am going to start off with that Offset command I just mentioned. Okay. Anytime you see this selection menu popping up, it's Rhino saying there is multiple items in close proximity. So, I will go ahead and select the Curve, and the selection menu will close. Go to the Curve menu to find the Offset, and it defaults to whatever value was used last. Looks like it's 1. I am going to change this to the ThroughPoint option, which basically means any number you select.
So, I can kind of move it around, and this is a great design technique, so if you don't know that something is supposed to be 1 or 2.5, you can just do what I call the Eyeball approach. So, whenever it looks good, you click, and now we've got a copy that is offset exactly whatever that number was. So, here is another cool part about this Offset command. I am going to do it over on the other eye by selecting and then repeat the command. Notice it is defaulting to the prior number I set, which was 2.001.
So, I probably want them to match. I will just go ahead and right-click to accept. So, there we have the exact same offset on both of those eyes. I want to go back to the Perspective viewport now. Maximize. I am going to zoom in to make this work a little bit easier, and I am going to select both of these curves at the same time. I am adding to them by holding down the Shift key. We would then go to Surface > Extrude Curve > Straight and again, we could type in a number at any time.
I am going to go ahead and type in 2. See how that looks. Now, it looks like it went the wrong way. It's actually inside. So, you got to be careful about the direction. So, I will Ctrl+Z, undo it and repeat the command. You can do that by right-clicking in the white area at the top command line. Extrude those same two curves again.
This is a good opportunity to mention this little tooltip here. It's telling me the exact dimension, and I should have noticed that. Right now, it's -2. So, the +2 that I typed in just went the other way, which was inside. I will just go ahead and eyeball that again, so now we can use that setting, whatever it was, for the other eye. So, I am going to select the curve, Shift to add the other curve, right-click to repeat, and then instead of typing a number or eyeballing it, I am just going to hit the right-click to enter the prior value.
Okay, we have got both eyes, already offset and then extruded. Now here is a very cool tip. This is my personal favorite command; I hope you agree. This is the Surface from Planar Curves. So, this is a great way to finish off surfaces when its face is in a single plane. So, if that doesn't make sense, it will soon. Go to Surface > from Planar Curves, and I am going to pick those two edges and right-click to accept, so check this out.
We have got a surface that is essentially capped, and it wasn't built from two curves. It was built from the edges. So, it's important to note that Rhino, many times, if there is a clean, defined edge, you don't have to have a line there. Many commands will look at edges or lines, and they are both treated the same. Another thing to note here is the ISO Curves we discussed earlier, these lines across the surface. We've got one going this way and the other going the opposite way. That's telling you something. This surface is as simple as it possibly could be.
So, that's another great reason use this command. It's always just going to close it off with the simplest possible surface, and that's always the goal. Okay. Let's repeat it again, Surface > from Planar Curves, and pick the two edges, right-click and we are closed off. You might want to follow up here by selecting the three new surfaces and just joining them together. The Join command is over here on main toolbar, so it's a personal preference.
You can do it anytime or at the very end of the file. It just may keep things a little more organized. All right. Let's jump back to the Front viewport for working on the mouth. Before I do this same Offset command, I would like to put a radius around all four corners. So, I am going to select that and go to the Curve menu, and I am going to Fillet Corners. This is a nice command, and it's similar to Fillet Curves but corners will do all four at once.
I wanted one. That's the default. I will go ahead and accept. Nice; all four are done at one time. So, that's the difference between Fillet Curves and Fillet Corners. If there's a hundred corners, it will find all of them. Fillet Curves is just a single intersection. Fortunately, the commands are located right next to each other, so if you forget, you can find them pretty easily. Let's go ahead and Offset this to give it a thickness. To do this, I am going to use Curve > Offset Curve, and go ahead and just match that same size of the eye and we will switch back to Perspective, double-clicking to maximize.
Now, instead of a Straight Extrude, we are going to try a little variation called the Tapered Extrude. So, I am going to start off with this outer curve here, Surface > Extrude > Tapered, and you can see a subtle angle here that's controlled by the DraftAngle option here. And I will type in 10 to make it little more pronounced, and that looks great. It can go both directions. But actually, I want it to taper that opposite way going out, no problem.
I don't have to type in -10. I can just go up here and Click FlipAngle, so that does the same work. So, I am going to go out -2. This time, I will type the number just for practice. So, there is an extrusion that is straight linear, but with the exact angle that I used. Let's do that inside of the mouth with the next curve. Surface > Extrude > Tapered. You actually want to go the opposite direction here, so I am going to flip the angle one more time.
Now, it could accept the prior dimension, but let's say you didn't know what that was. So, I will just demonstrate here. We can snap to one of these corners. Just turn on Quadrant Snap, and it will find the corners. So, now, I've matched that distance, if I didn't happen to know the exact number. So, I am just showing a couple of different ways to do the same end result. And now we will close this off with my favorite command, Surface > from Planar Curves. Select the edges, right-click, until it is undone, and there we have the mouth tapering in both directions about 10 degrees each, for a distance of 2 and capped.
Even though the Extrude command will generate very linear forms, including when tapered, it is still one of the most frequently using surfacing commands due to the variety of forms you can create. Of course, the quality of any surface is only as good as the curve or curves that generate it. So, make sure your curves are very simple and ideally flattened Planar. I also showed you how to create additional surfaces using the Curved Offset command and then close it off with a surface from Planar Curves. So, remember those.
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