Join Chris Reilly for an in-depth discussion in this video Drawing freeform curves, part of Up and Running with Rhino for Mac.
- Let's take a closer look at some of the Free-Form Curve commands in Rhino 5 for Mac. Here I've got a few different examples of Free-Form Curves. So we have some Sketch Curves, some Handle Curves, Interpolate Points Curves, and Control Points Curves, as well as this straight line PolyLine, just for reference. So Free-Form Curve commands in Rhino are located under Curve, Free-Form in the menu bar. We can also access them under the Curve icon, or just by typing them directly into the command line.
Now, in my file, I've got two layers of Guide Points that we'll use to draw out some example curves, and those are labeled Left Guide Points and Right Guide Points. And I'll go ahead and turn those on, just by clicking the little lightbulb icon, and you can see, there we go. I'll also make sure that I'm snapping to points in my Object Snap panel, and that'll help us out as we draw out our examples. So, let's look first at this Control Points Curve. And obviously, this curve looks different than the straight line curve below. It has some gradual changes to the curvature.
And what I've done to draw this out is to use each one of these Guide Points, to set a Control Point for the curve. And, I can view the actual Control Points by clicking on the curve, and selecting Edit, Control Points, Control Points On. And this shows me the actual Control Points of the curve. And I can see that, with the exception of the start and end points, the Control Points all lie off of the curve, and they're also directly on top of each of the Guide Points.
But, I can also see though, that even though most of the Control Points aren't touching the curve, they're still influencing the curve's shape. So see how it kind of gets pulled in either direction, towards each one of the points. So, Control Point Curves don't necessarily line up directly with their Control Points, but they're still influenced by them. We can see the same thing in this closed version too. Even though the curve doesn't actually touch any of the Control Points, we can sort of see how the curve's shape is being influenced by their arrangement. I'll turn Control Points back off.
And let's go ahead and draw a couple of our own Control Points Curves. So I'll go to Curve, Free-Form, Control Points. And now I can just start specifying points in space that will be my Control Points. And I can snap right to those points, because I have Object Snap on. And I'll just go along, setting this curve. Now if I accidentally set a point where I didn't want to, I can always come to this Undo option, in the command options, and I can just get rid of that one.
So I'll go back down, and on to the last one. Now, when I want to stop the command I can hit enter, or escape. And there we go. Let's try again with the closed version here. And I'll hit spacebar to activate that command again. And I'll start down here at the bottom, and just work my way around, snapping to each one of those points. Now to close off this curve, there's two things I could do. I could hit this Close command option, but since I have snapping activated, I'm gonna snap right to that beginning point anyway, so I know I'll be in the exact same spot that I started, and the curve will close automatically.
Let's move on and look at the Interpolate Points command. This command works a little bit differently than the Control Point Curve, so it tries to make a curve that passes through each one of the points that you pick. And I can see from the example that it's doing just that, it's actually passing through each one of these Guide Points. And the way that it does that is to draw separate Control Points. So if we turn Control Points on for this curve, I can see that the Control Points and the Guide Points are in different places. So the Interpolate Points command actually calculates its own Control Points, based on the points that we are telling it to pass through.
I'll go ahead and turn Control Points back off. And let's draw a couple of our own. So we'll go to Curve, Free-Form, Interpolate Points. And just like we did last time, I'll just snap to each one of these points. And when I'm done, I'll just hit enter, or escape, to exit the command. Ok, and on to the closed one. Again, I'll just hit spacebar to bring up that Interpolate Points command again. And just like we did last time, snap to each one of these points.
And at this point to close out the curve, again I could hit the Close command option, or I could just snap back to that beginning point, and that'll close it right out. Let's take a look at the Handle Curve. This command allows us to draw a special type of nurbs curve called a bezier curve, and if you've worked in programs like Illustrator, Inkscape or Corel, you might be familiar with this type of curve. So, if we click here, and take a look at the Control Points, we can see, they are kind of all over the place compared to the other curves we've looked at.
I'll turn that back off. So let's start our own. So Curve, Free-Form, Handle Curve. And here, we click once, to set an anchor point. Then we get these control handles, centered on the anchor point, and these help us determine the direction of curvature for each of the segments that we make in our curve. So now I get the next curve anchor point, and I'll set that, the next Guide Point. These control handles are a little counterintuitive at first, since you actually need to drag in the opposite direction that you want the curve to go, so if I want the curve to go up, I actually drag down, and vice versa.
So if I want to get something like this, I'll click here to set the control handle, and then I'm on to the next one. By default, your control handles will be symmetrical, but if I wanted to create sort of an abrupt change in curvature, so also called a kink, I can hold down the option key and that lets me set the two handles independently of each other. And there you see I get this abrupt change in curvature. Now I could also make a straight line segment, by setting the control handles in the exact same place as the anchor point, and luckily my object snapping makes that really easy.
And then I just get a straight line. I'll do the same for here, and when I get to the end, I can just hit enter, or escape, to finish out. So, once you get used to it, the Handle Curve is a really powerful tool for drawing complex shapes that are still really accurate. So, I'd especially recommend practicing with that one. Let's go ahead and do this closed shape too, so I'll go to Curve, Free-Form, Handle Curve. So I set my anchor point, then I need to do my control handles, and I'm just going to start to do a little pattern here.
And again, it does take some getting used to, but once you get the hang of it, this Handle Curve is so great for doing all kinds of complex shapes that otherwise would be really difficult. And again, because I have object snap snapping to points, when I go to set the last point, it's snapped directly onto the first point, which automatically closes out the curve. Lastly, we have the Sketch command. And this is the closest to kind of freehand drawing, so, I can see here, if I select the Sketch Curve, and I go to Control Points On, lots of Control Points.
A little bit similar to the Handle Curve, they're kind of all over the place. And they're different than the Guide Points that we use to draw. So I'll turn those back off. And let's go ahead and draw some Sketch Curves. So I'll go to Curve, Free-Form, Sketch. And to draw a Sketch Curve, all I do is click and drag. And I can pretty much go anywhere I want, I'll still pass through the Guide Points, just for consistency, but, again, very much like a freehand drawing.
I can do just about whatever I want. When I'm done I just let go, and Rhino does a little bit of cleanup, to sort of smooth out my curve. And similar to the Control Points Curve, Rhino makes its own set of Control Points for its Sketch Curves. Then I'm actually going to escape out of this command. So if I select that curve, and I go to Edit, Control Points, Control Points On, and see that Rhino's made its own set of Control Points, even though I snapped to each one of these points, Rhino kind of does its own thing, and steers it more towards what I actually drew.
This tool lends itself much more to expressive drawing, than accurate drafting, but sometimes that's exactly what we want. Go ahead and turn Control Points back off, and let's try to do a closed curve. So we'll do Curve, Free-Form, Sketch. And if I'd like to make a closed curve with Sketch, I can just activate this command option here. And that way, when I release my mouse button, Rhino automatically closes out the curve, so I'll just let go right here, and it closes it out.
Unlike the other Free-Form Curves, the Sketch command is a persistent command, so it's assuming that I want to do multiple Sketches, in sequence, and that why it stays active even after I release the mouse button. So when I'm finished, I can just click Done, or hit escape to exit out of the command. So that's an overview of drawing with the Free-Form Curve tools in Rhino 5 for Mac, and these tools, along with Straight Lines, and Curve Primitives, make up the full range of Curve tools in Rhino.
And practicing with all of these tools is going to give you a lot of great skills for more advanced modeling techniques that we'll cover later.
- Installing Rhino for Mac
- Viewing a 3D model in Rhino 5
- Manipulating objects with commands
- Creating curves, surfaces, and solids
- Applying transformations to 3D objects
- Creating unique shapes with Boolean operators
- Snapping to objects and planes
- Prototyping a 3D model
- Lighting and rendering