SketchUp

As mentioned in the Design in SketchUp topic, you can use the Line tool and the inference engine, to draw just about anything in SketchUp. It is recommended that you use the Line tool and inference engine to create your initial models.

SketchUp implements several concepts which you will use to help you draw quickly. These are dividing and healing, pushing and pulling, sticky geometry, autofold, and intersections.

Dividing and healing geometry

Some tools speed up design dramatically by allowing you to perform modifications on existing geometry. For example, the Line tool allows you to split faces and edges to create additional independent faces and edges. Simply divide the face or edge with another edge. This concept is similar to cutting a piece of paper in half and having two separate remaining pieces. The following image shows how two faces are created when dividing the face with a line. Notice the image on the left has one solid top face, while the image on the right has two independent faces when split with a line. Note that the dividing line does not cut through the model from top to bottom, but just cuts the top face in half.

The following image shows how the edges at each end of the face have been split to create additional edges. Note four edges bounding the face in the left image, while four edges bounding each of two faces in the image on the right (the middle edge being common to both top faces).

If you remove the line that shared by the two faces in the image on the right, the two faces will be glued back together or healed back into one face. It is common in SketchUp to perform these dividing and healing operations to your model.

Pushing and pulling

The Push/Pull tool allows you to take any non-curved face in SketchUp and push it away or pull it toward a starting point (these operations are also referred to as extrusions). Pushing is the process of reshaping a portion of your model by shrinking the portion away from its starting point and along a single axis. The following image shows the right-most face of the split face (shown earlier) pushed down toward the ground plane.

In the previous image, there are eight faces that can be pushed, can you find them (some are hidden out of view)?

Pulling is the process of expanding a portion of your model away from the starting point along a single axis. The following image shows the same face having been pulled up toward the sky. Any face in SketchUp can be pushed and pulled (with some minor limitations).

In both of the images, the left side of the cube remained the same size, while the right side was pushed and pulled (shrunk and expanded) independently. The Push/Pull tool is one of the most commonly used tools in SketchUp to add the sense of volume to your model.

Manipulating connected faces

Geometry in SketchUp is stickymeaning that it can be manipulated (skewed, distorted, or folded) by selecting an edge or face and moving the edge or face with the Move tool (causing all entities attached or 'stuck' to the edge or face to move too). Following are three examples of sticky geometry in SketchUp:

1. The following image shows a line dividing the top face of a box being moved up with a Move tool. The faces that were connected to the middle line followed the line as it was moved to create a roof-like effect.

2. The following image shows the left-most top face being moved down in the blue direction. This action causes the right-most top face to angle to create a slant on one side.

3. Finally, the following image shows the left-most top-edge being moved to the left. The model is skewed into a trapezoid-like shape.

Be sure to use the Move tool to grab and move edges and faces while you begin to experiment with modeling in SketchUp.

Autofold

Faces must remain planar at all times in SketchUp. Therefore, SketchUp will Autofold, or score, faces as necessary to accommodate any operation that will result in warped faces.

In the left-most image above, a six-sided polygon volume's top face (created with the Polygon tool followed by the Push/Pull tool) was rotated using Rotate tool. Because of SketchUp's sticky nature, the sides of the shape, which share common edges with the top face, twisted and folded with the rotate operation (right-most image).

What you are not seeing is that SketchUp has created hidden geometry when performing this Autofold operation. The following image shows the 3 dimensional shape with the hidden geometry shown (dotted lines). Notice that each twisted faces are actually comprised of two triangular faces.

Intersections (boolean operations)

SketchUp allows you to easily create complex geometry by intersecting two geometrical forms, such as a box and a tube, creating new edges where the elements intersect, merging the geometry, and subtracting parts of the combined geometry.

In the left-most image above, a cylinder shape was moved into a cube shape. Notice, that no lines appear where the two shapes intersect, indicating that the shapes have not truly merged. A special tool, called the Intersect with Model tool, is used to create intersection lines (the middle image), merging the two shapes together to form one new shape. Finally, the cylinder shape is deleted (using the eraser tool on the cylinder's edges) and because the intersection lines were created, the resulting curved face is left within the cube creating a new complex geometrical shape (right image).

SketchUp tools

Most entities in SketchUp, including arcs and circles, are actually just a combination of small lines or edges. Thankfully, you do not have to use only the Line tool to sketch your models. Instead, SketchUp provides many other tools to help you draw quickly. Some of these tools are for creating common entities such as a circle, arc, polygon, or freehand line. Other tools allow you to quickly draw complex models by modifying your models (splitting, skewing, and even merging geometry together).

Tools in SketchUp are divided into five categories: principal tools (tools that are used a lot to select and modify geometry), drawing tools (tools used to create geometry), modification tools (tools used to modify existing geometry), construction tools (tools used to create construction lines or points, and document your model), camera tools (tools used to view geometry; discussed later), and walkthrough tools (tools to explore your model). The following table lists all of the Drawing, Principal, Modification, and Construction tools:

*These menu items are available in menus, not from the toolbar (Microsoft Windows) or tool palette (Mac OS X), and are discussed in the tools sections of this user's guide.

Each of these tools is discussed further in this guide. As a recommendation, however, learn the Line tool and Eraser tool first, followed by the Orbit tool (discussed in the next section), Push/Pull, and Move tools.