Five Core Concepts

SketchUp is an excellent design tool that gives designers the flexibility they need to sketch in a 3D digital world. SketchUp was once considered useful only for preliminary schematic designs; however, if you incorporate the organizational techniques taught in The SketchUp Workflow for Architecture, SketchUp is capable of much more. In this section, you’ll learn about the SketchUp tools, environment, and how to use collections and ruby scripts. Before you get into the details, however, you need to make sure you are up to snuff on the basics and that your default SketchUp template is optimized for professional use.

SketchUp Basics

n order to use the methods in this book, you must understand the concepts, tools, and commands presented in this chapter. Any additional knowledge you have is a plus. However, don’t underestimate the usefulness of this chapter, even if you already consider yourself a SketchUp expert. It has plenty of tips, tricks, and helpful theories that will come up again later.

Five Core Concepts

Figure 4.1  All of the endpoints (corners) of the triangle are at the same blue eleva- tion—in other words, the edges are all on the same plane (coplanar).

Before you even open SketchUp, you need to understand the core concepts that make it unique. First, SketchUp is a surface modeler that is unlike most 3D modeling programs. Everything in SketchUp is composed of edges and surfaces, the basic building blocks used in SketchUp. A surface cannot exist without a closed loop of coplanar edges, and the simplest surface possible is a triangle (Figure 4.1).

Figure 4.2  Circles and curves are represented by a series of smaller line segments. Increasing the number of segments makes a smoother circle, but can also decrease computer perfor- mance and lead to large file sizes.

Second, because it is a surface modeler, there are no true, perfect vector curves, arcs, or circles in SketchUp. However, you can still represent circles and curves with a series of small edges (Figure 4.2).

Figure 4.3  Adjacent geometry sticks together in SketchUp.

Third, SketchUp geometry has a tendency to stick together. This concept is known as the “stickiness of geometry” in SketchUp. Adjoining surfaces stick together and move with each other. Connected endpoints will move with each other and stretch their corresponding lines (Figure 4.3). Even though this can be frustrating at first, once you learn to control the stickiness, you will realize how much it speeds up the modeling process.

Figure 4.4  Stacked edges merge into one with edges seg- mented at the overlaps.

Fourth, geometry does not stack in SketchUp. Only one edge or surface can exist between the same series of points. Even when multiple edges are drawn on top of each other, the edges simply combine into one. When an edge is drawn that intersects or overlaps an existing edge, the existing edge will be broken into two pieces (Figure 4.4).

Figure 4.5  Most inferences require modifier keys or hovering on entities to “encourage” an inference.

Lastly, the inference engine is the “brain” in SketchUp that is always working for you; it is what assumes meaningful relationships between points, edges, and surfaces. Although you can’t turn off the inference engine, you can control it through the power of suggestion. There are several inferences available in SketchUp, some are shown in Figure 4.5.

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