From the course: 3ds Max 2026 Essential Training

Editing Bezier splines - 3ds Max Tutorial

From the course: 3ds Max 2026 Essential Training

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Editing Bezier splines

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- [Instructor] A parametric shape primitive, such as a circle or a rectangle, is non-destructive and reversible. It's based upon parameters. If we wanted to go in and edit the shape of that curve directly, we could convert it to a so-called editable object. Then we'll have the ability to, for example, select and manipulate the points on a Bezier curve directly. Let's go through that process. I'll go to the Create Panel, to the Shapes sub-panel, maximize my front view with Alt + W, and click on the circle button. Just drag out to create that circle. Release the mouse. Right click to exit circle creation, and go to the Modify panel. Because this is a parametric primitive, we have a radius parameter, and that is non-destructive and reversible. We can set the radius value to whatever we want and maybe change it to 100 instead of 200. We can always change it back to where it was. Set it back to a radius of 200, and we have the exact same result. It is a reversible, non-destructive primitive. If we convert this to an editable object, we'll lose any parameters that the object may have. But we will gain the ability to manipulate the parts of the object independently to customize the shape. When we save a 3ds Max scene that has a parametric primitive, either a shape or a 3D primitive, 3ds Max does not store the absolute position of all the points on that primitive. Instead, it stores sort of the recipe or instructions for creating that object. It simply stores the fact that it is a circle primitive, it's located at a certain location, and it has certain radius parameters in this case. If it was a rectangle, it would have length and width parameters instead. So it doesn't actually store the object per se. It stores instructions for creating the object, and every time the scene is opened, 3ds Max rebuilds the object from nothing using those instructions. This is one reason why parametric primitives are so lightweight in terms of disc space. It doesn't actually store the positions of the points on the object explicitly. It just stores their recipe. Okay, if we want to work with this directly and customize its shape, we'll need to bake the cake. In other words, we'll need to convert this from the recipe to an actual editable object. And one way to do that is to right click anywhere in the viewport, you'll get the popup quad menu. Now at the bottom, we'll see Convert To. You've got a bunch of options. We want to choose Convert To Editable Spline, and watch what happens in the Modify panel. Okay, it's no longer a parametric primitive, it's not a circle object type anymore. It's now an object type of editable spline, also known as a line. And now we can go in and select the various parts, which in 3ds Max are called sub-objects. We can access the sub-objects by going to the modifier stack here in the Modify panel and opening up the base object type, and we'll see its sub-object types listed. We can, for example, choose vertex, and those are points. We could also go down into the Modify panel to the selection rollout and choose one of the icons there. We can see that the vertex icon is lit up right now. We could also choose segment, and that is a span between two points. I could click on a segment just to show you. There's also the spline sub-object, and again, we get selected either here in the selection rollout or in the modifier stack. I could choose spline, and if I click on the circle, the whole circle is selected. A spline object could have multiple curves inside it. It could have multiple splines. For example, a text object is going to be built out of many different splines in the same object, and we could select and manipulate all of those independently. We're just going to work with vertices, which is the plural of vertex. I'll choose vertex sub-object type, and I can select a vertex. And you can see, because this is a Bezier control vertex or control point, it has these tangent handles. You might be familiar with those from a program like Photoshop or Illustrator. I can either move the point or its tangent handles to change the shape of the object. I'll go to the Move tool and move that point around. Or I could select and click and drag on these tangent handles. Now, let's talk for a moment about the Transform Gizmo. I'll undo that with Control + Z. In certain situations, the Transform Gizmo can actually get in your way, and this is one of those situations. I'll dolly back a little bit, Control + Alt + Middle Mouse just to make it easier to see what's going on. Let's say I wanted to move that control vertex in the X axis of this viewport left and right. If I click on that and try to drag it left and right, I can't, and it's because it's directly underneath the Transform Gizmo, and when I click on it, I inadvertently click on the Y axis of the Transform Gizmo. So to work around that issue, you can hide the Transform Gizmo, and go up into the Views menu, and turn off Show Transform Gizmo, and now you won't accidentally select an axis when you don't want to, but now how do you change what axis you're working in? The Transform Gizmo is actually just a shortcut to something called the Axis Constraints Toolbar. Let's make that visible. I'll right click on any of the grab bars, the textured bars on the top or side of the toolbar or panel. I get a list of all the user interface elements. I want to enable the Axis Constraints Toolbar, and I can move that around or dock it if I want. This is now telling me what axis I'm moving in. It says the Y axis, so that's going to be up and down. If I want to move side to side, I'll choose X. I'll undo that with Control + Z. If I want to move in both X and Y, I would choose XY here. All right, and just as an aside, if I wanted to choose some other plane to transform in, I could hold down this icon and get a fly out and choose some other plane in which to transform. Okay, so I don't need that anymore, I'm going to hide that once again, I'll right click on the grab bar and turn off the axis constraints, and I'll turn my Transform Gizmo back on again. Again, this is a Bezier control vertex. There are other types. We can convert in between them using the quad menu. Let me move this over a little bit. We'll make it kind of crescent moon shape. I'll select the top and bottom vertices here, and those are, once again, Bezier control points. I'll right click to get the quad menu, and in the upper left quadrant in the Tools 1 section, we'll see a list of the vertex types, and there's a checkbox next to Bezier. I can convert these to corner points by choosing Corner. Now there are no longer any Bezier tangent handles, and we get a sharp corner at that vertex. All right, cool. Let's select these two points, and we'll convert them to a different type, right click, and we can choose smooth. And smooth control points don't have tangent handles, and that makes it a little bit easier for you to manipulate them, but they don't always necessarily do exactly what you want. You can't customize the transition or interpolation between these two points. The shape of that segment is going to be entirely determined solely by the positions of its end points. And also if I select these other points on the ends and right click and convert them to smooth also, if we move any one of these around, we can see that we're changing the shape of the entire curve. Just like we saw in the last movie with NURBS, it's kind of the same thing. We don't really have very good localized control over those shapes of those splines using smooth vertices. Okay, I'm going to convert these two back to corner, and I'll convert these ones to something called Bezier Corner. And that gives us the ability to manipulate these handles independently if I want, okay? I'll undo that, Control + Z. What I really want is just Bezier. So with those two vertices selected, I'll right click and once again choose Bezier, and then I can proceed to, in the Y axis, shape these Bezier tangent handles in order to get a sort of crescent moon effect. Very cool. Now one last point is, unlike some programs, the Bezier tangent handles at the ends of these points are not actually sub-objects. They're not listed here. We don't see an entry for tangent handles. Because of that, we actually cannot select more than one tangent handle at a time. They're really just manipulators for controlling the interpolation or the shape of the adjacent segments. We can only manipulate one of these at a time, unfortunately. All right, so once I'm done, I can exit out of sub-object mode. Back in object mode, I've got my crescent moon shape. That's how to work with Bezier splines and sub-objects.

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