From the course: Learning Rhino 6 for Mac

Surface basics - Rhino Tutorial

From the course: Learning Rhino 6 for Mac

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Surface basics

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- [Narrator] Let's talk about some basic properties of NURB surfaces in Rhino for Mac. To help us out, I've got the exercise file surface basic stuck, 3D em open. And here, we have some examples of different kinds of surfaces. You can imagine a surface in Rhino as starting out as a rectangular piece of fabric, and it's a very very stretchy kind of fabric. And we can use that stretchiness to contort it into all sorts of different shapes, even ones that don't look rectangular or flat. And sometimes we can also trim off parts of the surface to change the shape even more. In Rhino, surfaces have many of the same underlying properties as curves. So for example, surfaces have control points and these are what allow us to stretch out that fabric of the surface. Let's take a look at some control points on these surfaces. And I'll turn those on under the edit, control points, control points on, menu. And I'll just go ahead and click and drag from right to left, to do a crossing selection and grab all these surfaces and then click done. So I can see all my surfaces have control points. Some have more, some have less. And if we zoom into any, I can see that editing the control point, edits the surface. And I'll just command Z to undo that. Back up to the edit menu, let's turn our control points back on. So that's edit control points, control points off. In addition to control points, surfaces also have local coordinates. So if we think again about the fundamental start of any surface in Rhino as being a rectangle, we can imagine that rectangle as having a two dimensional grid covering it. And we call that grid the UV coordinate system. Where local surface coordinates run in the U and V directions. Let's take a look again at this surface. And I can imagine this surface as a little sheet of graph paper, where I have the origin down here at zero zero, and I have the U and the V directions going out to either side. I can get specifics of the UV properties of a surface with the evaluate UV point command. And that's under the analyze surface menu. And it's this one called UV coordinates of a point. So I'll click to activate that, and then I'll select the surface to get UV values from. So as I click here and different parts of the surface, I can see down in the command history. I'm getting the U and the V coordinates of each point. And in my case, it looks like the U and V domains of the surface range from zero to one. And that's usually the case with most surfaces, though sometimes you'll have different domains. So let's click done on that command. And you'll see, I get the list of UV points that I picked. So in addition to control points and UV coordinates, surfaces also have direction, and that kind of acts like the front and the back of a surface. And we can see that direction with the direction command and that's under the analyze menu. So let's try direction with this surface here. We'll just select it and click done. So now I can see my surfaces tagged with these little white arrows, and those are telling me a couple different things. First they're showing the general direction of the surface so I can see they're generally pointing up. And that tells me that I'm looking at the front of this surface from the top. If I rotate down and look from underneath, I can tell that this is the back of the surface because all the arrows are pointing away from me. I can also see the surface normal. This little set of axes here. That's following my mouse. Those show me the directions that are perpendicular to the surface at any given point. Okay, let's click done here. Now surfaces can also be open where their edges don't match up to the edges of any other surface. So lots of these surfaces here are open. They can also be joined together with other surfaces to form poly surfaces like these two here. And if I need to get more details on that, I can look in the object properties inspector and click the details button. Under geometry, I can see this as an open poly surface with two surfaces. And just like with curves, surfaces can be periodic where their seams are smooth. So kind of like this cylinder here, or they can be non periodic like this one where there's kind of a kink at the seam where their start and end meet. Some surfaces can also be totally close, then that's when all of their edges meet up exactly with other surface edges. Now those are special class of surfaces called solids, and we'll cover those in detail In another video. Rhino for Mac also has a special kind of surface called the Lightweight Extrusion. And these are defined very simply just by a profile, a curve and a height. So these two objects here, the cylinder and the free form shape, these are both Lightweight Extrusion objects. And the point of introducing these into Rhino is that they don't take up as much memory as normal surfaces or poly surfaces. And they behave a little bit differently and we can see that if we turn the control points on for either of these surfaces. So shift select both of those. Let's go back to edit under control points, turn control points on. Now you can see, I only get two points for each of these surfaces and these allow us simply to control either the height or the orientation of the extrusion. So I'll click on one and turn the gumball on. You can see now that as I drag this up, my extrusion height changes, I can also rotate, and that allows me to set the orientation of the extrusion.

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