Surfaces
Introduction
Expected Time: 15 min
Creating surfaces doesn't differ much from generating them in Rhino. The main four modeling options of extrude, sweep 1 rail, loft and planar are also available in Grasshopper. However, the major difference is the input geometry. This can be a set of points or curves. Especially the use of points is something which is less used in Rhino. Points in Grasshopper can be useful for coupling it to other parameters, influencing the location of the points. Thereby creating triggers which might deform the surface.
The techniques are relatively the same in Rhino as in Grasshopper. We have the main four options of:
- Extrude
- Sweep 1 rail
- Loft
- Planar
In this tutorial, we will discuss the extrusion and loft method, since they are mostly used in Grasshopper.
Extrude
The example on the right uses the extrude component to extrude an existing curve in Rhino.
- Set a curve created in Rhino to a curve parameter in Grasshopper
The extrude component is used to make a straight extrusion. Other extrusion options are also available. The direction and distance are controlled by a vector.
- Add a vector to the canvas
- Give a x, y, and z value to the vector with a number slider
The distance of the vector is controlled by the amplitude. This is, in fact, the length of the extrusion.
- Connect an amplitude to the output of the vector.
- Add a number slider to the Amplitude input
- Use an extrude component to extrude the geometry
- Draw a connection line between the amplitude output and direction input
- Add a surface parameter for good practice
Your script is now finished. You can "bake" the object by right-clicking on the surface parameter and click on bake. This will get your surface into Rhino for further modelling.
- Bake your final surface
Loft
When you have existing curves that you use to make a loft, you may want to change the position of these curves. You can do this using the move or rotate component. The move component uses vectors to specify the direction and distance.
- Create a curve in Rhino and set it to a curve parameter
The first curve is moved in the Z-direction and X-direction by using a Unit vector component. The length of this Unit factor is changed by using the Factor input with a Number Slider. The vectors can be combined using an addition component.
- Add a move component to the script
- Connect an addition node to the motion input
- Add two unit vectors (X and Z) to the addition input
- Add a number slider to the unit vector input
Finally, you have to connect the original and moved curve to a loft component. Make sure you connect the curves in the right order to the loft component! Otherwise this may not give the result you expect!
- Connect the original curve to the loft component
- While holding the shift key, connect the moved curve to the curve input of the loft node
Of course, you can also rotate the moved script. This will result in the following script.
For good practice, always add a parameter at the end and rename your sliders.
- Add a final surface parameter