Google SketchUp: The Missing Manual

Editing Geometry

When you're building complex models, the difference between perimeter edges and shared edges (Creating Complex Shapes) becomes more important. In SketchUp 7, when you draw shapes that overlap, they create intersections where the lines meet. In earlier versions of SketchUp this wasn't the case. In a two-dimensional image that difference may not be important, but when you start working in 3-D, the relationships of edges and the way shapes intersect become important (see Intersections in 3-D Objects). This section shows some tricks of the trade to turn perimeter lines into shared edges that you can then erase, simplifying your model.

In the following steps, you'll use this technique to lengthen Skeeter's shirt:

1. Draw a rectangle that crosses over the bottom of the rectangle of Skeeter's shirt.

   When you've created the rectangle, it should look like Figure 2-25.

2. With the Select tool, select some of the different lines in the rectangle.

   The longer lines were broken up into shorter line segments wherever the lines intersected.

   Note

   SketchUp 7 behaves differently than previous versions. In SketchUp 7, two lines or edges crossing in a single plane split into four segments at the point of intersection. In previous versions, crossing lines had to be explicitly split by tracing over the lines.

3. Use the Eraser tool to erase the shared edges so that Skeeter's shirt becomes a single face.

   You can delete each shared edge using the Eraser tool. If you lose a face that you intended to keep, ...