Join George Maestri for an in-depth discussion in this video Creating arcs, part of Maya 2013 Essential Training: 3 NURBS Modeling Techniques.
Now, if you want to create curves that are circular in nature, such as arcs or ellipses, you can use some special tools in Maya. We do have a Circle tool as well as arc tools. So let's take a look at these. Now if I wanted to create just a circle, I could go into Create > NURBS Primitives > Circle, and this basically just creates a basic NURBS circle. All I have to do is left-click on the grid and drag and I have a circle.
Now if we want to, we can take a look at the inputs here. We have basically a Radius. We have a Sweep. So if I want to, I can use this Sweep to create an arc. And then I also have a number of sections, and those are very similar to what we had with the cylinder and the sphere, and that's how many CVs are around the edge of this? In this case we have eight. And if I right-click on this, go on to Control Vertex, you'll see that I have basically eight sections around here.
Now once these curves are created, they are just a standard NURBS curves, so I can just manipulate them however I want. So I'm going to go ahead and right- click, Object mode, and let's delete this. Now in addition to the Circle tool, we have two additional arc tools, the Three Point and the Two Point Arc. So let's take a look at those. I'm going to hop out of my perspective mode and let's go into top view here. We're going to go Create > Arc Tools, and let's start with the Three Point Circular Arc, so I'm going to go ahead and select this and let go.
We get a creation icon here, so I just going to basically left-click to place the points. And then the third point you click determines the arc that you create. So basically, you're laying down two anchor points and this third point is interactive. And we can also grab each additional point to fine-tune this. So as we're creating, we can go back and fine-tune this.
Now once we're done with this and hit Enter, it does become a regular NURBS curve. Now I can go into my ThreePointCircularArc and here are all my creation parameters. If I want, I can change those if I need to. But once I go to edit this, I do get the standard NURBS Curve tool. So I can also just edit this like any other CV curve. So again, Object mode. Let's select this and delete it. And let's take a look at the very last arc tool, and that is called the Two Point Circular Arc, and it's pretty straightforward.
You select one point, two points, and now we've got some control here. So this control here determines which direction this arc goes, this little glyph here. We can reposition what I would call the feet of the arc. And then this controls how deep or shallow the arc is. So this middle point controls the curvature, this one controls which side of those points it's on, and then these two actually control the shape.
And again, just like with the Three Point Arc tool, as soon as I click off of this, they go away. So if go to Select mode, it becomes basically a CV curve. Now I can go into my inputs, either in the Channel Box or the Attribute Editor, and change these however I want. But a lot of times it's just easier to right-click over this, go into Control Vertex, and just manipulate my points. So we have three basic ways of creating arcs and circles in Maya.
We can use the Circle tool, which can also create arcs, and then we have the Three Point and the Two Point Arc tools as well. Now all of these create CV curves, in other words curves that have control vertices, that we can use to further manipulate the curves after creation.
- Creating NURBS primitives
- Manipulating NURBS surfaces and curves
- Detaching NURBS surfaces
- Creating Bezier curves, arcs, and text
- Opening and closing NURBS curves
- Duplicating curves
- Working with the Resolve, Loft, Extrude, and Planar commands
- Creating curves on a surface
- Trimming surfaces
- Working with NURBS Booleans