Architectural_Design_with_SketchUp

Chapter 6 Creating Geometry Using Ruby Scripting
Groupon, and Hulu are among them) run on code
written in Ruby. Besides, it is a very object-oriented
language that is actually quite easy to learn, as you
will see. (See Figure 6.3.)
SketchUp itself provides a large variety of tools
and procedures that are available to the Ruby scripting
language using what is called an application programming
interface (API). This gives you access to tools
such as Move or Copy, as well as the entire collection
of materials in your SketchUp model, through
many well-documented functions.
Having said all of this, it is important to note that
any tool or method has its limitations. Consequently,
scripting in SketchUp also has limitations. For example,
curved shapes are not implemented as perfect
curves, in SketchUp’s tool set nor in the API. Because Figure 6.3: The Ruby language’s website
SketchUp is a polygon-based modeling software, it
naturally does not have a way to define perfect curves. As you know, circles are always made
up of several polylines in a SketchUp model. While this certainly is a limitation, it is also important
to keep in mind that in real construction, curved shapes may be approximated by planar
elements (e.g., plane glass panes on a curved-looking facade)—often for constructability and
cost reasons. As a result, SketchUp’s API does not natively support NURBS (nonuniform rational
B-splines)—at least not without a plugin. This is better implemented in other software
programs (McNeel’s Rhinoceros and Autodesk’s AutoCAD, Revit, and Maya, for example).
Nevertheless, creating scripted geometry is quite possible using the freely available version
of SketchUp, which lowers barriers of entry and offers the potential for everyone to dabble
in this exciting field and create advanced geometry.
This chapter approaches SketchUp scripting in a pragmatic way. This means that every
step in the process of geometry creation and manipulation does not necessarily have to be
scripted—after all, we are not writing a plugin, and SketchUp already has a great set of builtin
modeling tools. We’ll script only what can’t efficiently be modeled by hand, using standard
SketchUp modeling tools to start or finish a project.
First, let’s set up your computer so that you can easily script using Ruby.
Setting Up Your Computer
Before we do any modifications to SketchUp, let’s use Ruby as
SketchUp provides it to get you started quickly. In SketchUp,
look for a menu item in the Window menu called Ruby
Console. When you click on it, you should see the dialog
shown here.
This is the built-in interface for the Ruby scripting language.
It works simply by accepting a line of code in the text box at
the bottom. Once you hit Enter, the line is executed, and the
result appears in the field at the top of the box.
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