From the course: Learning Rhino 6 for Mac

Curve basics - Rhino Tutorial

From the course: Learning Rhino 6 for Mac

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Curve basics

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- [Narrator] To get familiar with using curve objects in Rhino for Mac, we need to know some basic curve properties. Rhino has a number of different curve commands and those are located under the curve menu. Any of these options lets us draw one of three main types of curve and we can see some examples of each in the exercise file curve-basics.3dm . Primitives are shown in blue, straight line curves in black and free form curves in magenta. I've also labeled each grouping with a command I use to draw them. Let's talk first about primitives these include shapes like rectangle, polygon, circle, arc and a few others. They're called primitives since they have some standardized properties. Freeform curves can take basically any shape we want and then we have straight line curves, which may seem like an oxymoron since you'd expect a curve by definition to be, you know, curvy but in Rhino we define a curve more in a mathematical sense than an aesthetic one. So all curves in Rhinos share some basic properties, so for example, all curves have control points as well as start and end points and that's what determines the shape of each curve. We can see these points any time simply by selecting a curve so I'll go ahead and select my interpolate points curve, control points. So we can see each of these white dots is a control point and I can even grab one of these and move it around and change the shape of the curve, curves can also be planar or non-planar. Planar means that all of the curves points can be intersected by the same plane. Now that could be the construction plane as the case for our free form and straight line curves or just another plane in space. Non-planar curves have points that occupied multiple planes, such as the spiral and the helix curves here. Let's switch to perspective to get a better look. So I'll double click on top and then double click on perspective. So we can see here, the spiral in the helix extend outside of that construction plan while all the other ones sit flat and let's go back to top. Curves can also be open or closed a curve is open when the start and end points are in different locations. So our open sketch curve, our open handle curve and all these ones that don't meet up at the end points are open, with a closed curve the start and end points are identical. So these ellipses, the circle, a few of these other ones that enclose a space are all closed curves. We can also chain together multiple curves to form closed boundaries. So for example, this shape here, this is obviously a closed shape, but it's actually made up of individual segments that are chained together. Likewise for the rectangle, polygons and our handle curve here and we can get more detailed information about all these properties of curves through the object panel under the detailed section. So let's go ahead and select this sketch curve and over on the right sidebar. So I'm in the object properties panel, I'll click the details button and you can see, we get a lot of information about this piece of geometry and under that geometry section here, I can see a little report and so here, Rhino is showing me some details. this is a valid curve, it's an open NURBS curve and I can see some additional properties, for example the degree. So degree determines how curvy or how straight a line is capable of being and let's go ahead and try a different one. Let's click done here, so let's click on this closed interpolate points curve and get the details. So this is a valid curve, it's a periodic NURBS curve I can see that the start and end points are the same. So that's telling me it's closed, I can also see that it's closed. Periodic curves by definition are closed and they're defined as periodic when there's a smooth transition from the start to the end point. Non-periodic curves can still be closed, but they'll have an abrupt change, which is sometimes called a kink at the point where the start and end points meet. Let's click done for now and so we can see a non-periodic curve here with this close control points curve, let's click the details. So I can see that it's a valid curve and it's closed, but it's not telling me that it's periodic. So, this is not necessarily a periodic curve so I'll go ahead and click done. So that's an overview of just some of the fundamental curve properties in Rhino for Mac and knowing these will really give us a lot more control and predictability as we go on to make complex curves and surfaces in other videos.

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