An Intermediate Google SketchUp Tutorial - Part 3.pdf - Sketchup - aleks742

An Intermediate Google SketchUp Tutorial - Part 3

Note: Before reading this tutorial see Notice in the last paragraph.

In this installment we are going to introduce some new tools that allow us to use curves other

than circles or circle segments (arcs). These curves fall in a class called Bezier Curves (or

Splines). For the technically inclined you can go to Wikipedia for a detailed description. Our

interests as woodworkers are in using Bezier curves to form complex shapes such as Queen

Anne legs. The bad news is the tools needed do not exist in the SketchUp. The good news is you

can get them in a Ruby script and install them into SketchUp.

The Ruby script we will use is actually a number of scripts, icons and other files. So you have to

download a .zip file called bezierspline.zip . I recommend downloading it and saving it to disk

before unzipping. I am not going to explain how to use ZIP files or how to install Ruby scripts

into SketchUp. I assume you know how to do that by now. If you don¶t there are many places on

the Internet to get help, or contact me through email or phone and I will help you (see Contact

menu above). Maybe I will put this on a list of future tutorials. But for now you are on your own.

Download bezierspline.zip and install the unzipped files. In the unzipped files you will see a

number of Adobe files. One is a user¶s manual and one is a quick help file that explains

installation. You might want to read the latter at least.

When you have installed the scripts be sure to go to View/Toolbars and check Bezier Toolbar.

Now you should have tool icons that look like those in the picture above left. I should pause here

to say that most Ruby scripts are provided free. Some cost a few dollars, but generally they are

free. They are written mostly as a hobby or need, by people like us or software engineers that

can¶t help themselves - they need to hack. Consequently, these scripts do not receive the level of

testing that commercial software does. So you might expect an occasional strange behavior,

though my experience has been quite good. Also, since you are getting the source, most authors

allow you to modify the scripts yourself to tailor them to your needs. I do this a lot. But read

what is said in the source about copyright. Don¶t violate the license. These people are very

helpful to you and I. We want to keep them active and sharing.

Bezier curves can be difficult to use, at least the lower order ones. I will show you a comparison

of each of the four types available here and then we will focus on the one that I find most useful.

In the second picture above right is a grid I drew to compare these curves. I have placed a

number of construction points on this grid which I will use with all curve types (by the way the

grid and construction points were drawn using two other Ruby scripts). The curves I will draw

will intentionally exaggerate problems with each type by using a closed curve which is only

concave. But that will highlight why some are more difficult to use to get the shape you want.

Click to enlarge the picture and observe the guide points.

The first curve I am going to draw is the Classic Bezier Curve using its tool. The result is shown

in the third picture above left. I started at the lower left corner and clicked on the starting guide

point. Before clicking again I hit the shift key twice, quickly, which changed the red X to an

orange solid triangle. What this does is allows me to plot points of the curve in order. If I don¶t

do this I have to plot the first point, then the last, and then successive points after the first. Very

confusing. I do this for all curve types. Next I clicked on each guide point as I went around in

clockwise order. After clicking on the last point (the one BEFORE the start point) I right clicked

and chose ³Close loop nicely´. I immediately right clicked again and chose ³Done and Exit

An Intermediate Google SketchUp Tutorial - Part 3.pdf