How to Use T-Splines in Rhino for Smooth and Flexible Modeling
T-Splines are a type of surface that can be used in Rhino to create smooth and flexible models. T-Splines are different from NURBS surfaces, which are the standard type of surface in Rhino, because they allow more control over the shape and topology of the surface. T-Splines can also be converted to SubD objects, which are a new type of geometry in Rhino 7 that can be edited with simple tools like push and pull.
In this article, we will show you how to use T-Splines in Rhino for various modeling tasks, such as creating organic shapes, editing complex surfaces, and importing and exporting T-Spline objects.
Creating T-Spline Objects
There are several ways to create T-Spline objects in Rhino. One way is to use the T-Spline commands that are available in the T-Splines toolbar or menu. These commands allow you to create T-Spline primitives, such as planes, spheres, cylinders, and tori, or to draw T-Spline curves and surfaces from scratch. You can also use the Append command to add faces to an existing T-Spline object.
Another way to create T-Spline objects is to convert NURBS objects to T-Splines using the Convert command. This command allows you to convert NURBS curves, surfaces, polysurfaces, or meshes to T-Splines with different options for preserving the shape or simplifying the topology. You can also convert SubD objects to T-Splines using the same command.
Editing T-Spline Objects
Editing T-Spline objects is similar to editing NURBS objects, but with some differences. One difference is that you can switch between two modes: box mode and smooth mode. Box mode shows the control points and edges of the T-Spline object, while smooth mode shows the smooth surface. You can toggle between these modes by pressing the Tab key. Box mode is useful for making coarse adjustments to the shape and topology of the object, while smooth mode is useful for making fine adjustments and seeing the final result.
Another difference is that you can use some special tools that are specific to T-Splines, such as Insert Point, Delete Point, Weld Point, Slide Point, Extrude Face, Bevel Edge, Bridge Edge, Fill Hole, and more. These tools allow you to modify the shape and topology of the T-Spline object in various ways. You can also use some standard Rhino tools that work with NURBS objects, such as Move, Rotate, Scale, Trim, Split, Join, Boolean, and more.
Importing and Exporting T-Spline Objects
If you want to import or export T-Spline objects from or to other software applications, you need to be aware of some limitations. One limitation is that not all software applications support T-Splines natively. For example, Autodesk Maya and Autodesk Fusion 360 can import and export T-Splines directly using a .tsm file format. However, other software applications may not recognize this format or may have different implementations of T-Splines.
Another limitation is that Rhino does not support T-Splines natively either. You need to install a plugin called Autodesk T-Splines Plug-in for Rhino[^1^] [^2^] that adds the functionality of creating and editing T-Spline objects in Rhino. This plugin works with Rhino 5 and Rhino 6 only. If you want to use T-Splines in Rhino 7 or later versions[^1^], you need to convert them to SubD objects first[^1^]. SubD objects are similar to T-Splines but have some advantages such as better compatibility with other software applications and better performance in Rhino.
To import or export T-Spline objects as SubD objects in Rhino 7 or later versions[^1^], you need to follow some steps[^1^]. To import a T-Spline object as a SubD object[^1^], you need to open your model in Rhino 5 or Rhino 6 first[^1^], then save it as a .3dm file[^1^], then open it in Rhino 7 or later versions[^1^]. To export a SubD 061ffe29dd