As you draw 3D models in SketchUp, the ability to divide edges and faces enables you to create and manipulate your geometry in complex ways. You can also explode entities, such as circles and polygons, into the individual segments.
Dividing a line or arc
SketchUp automatically splits a line segment when a new line is drawn perpendicular to that line. For example, two lines are drawn perpendicular to each other on the face of the cube. In the figure, notice the following:
- These lines divide the edges that form the cube as well as the lines on the cube’s face.
- Sections of what appear to be whole lines are selected, because the lines are split by other lines.
The lines don’t have to be perpendicular. You also split a line or arc when a line crosses another line or arc on a face, as shown in the next figure.
When you want to divide a line or arc into equal segments, SketchUp helps you out. Simply follow these steps:
- Context-click a line or arc.
- Select Divide from the context menu. SketchUp place points on the line or arc to show where it will be divided.
- Move the cursor toward the center of the line or arc to reduce the number of segments. Move cursor toward either end of the line or arc to increase the number of segments, as shown in the figure.
Tip: Notice that the Measurements box dynamically changes to Segments. If you prefer, you can type a number and press Enter and thus skip Step 4.
- Click the line when the number of segments you would like is shown. The line is divided into an equal number of joined line segments.
Welding a series of line segments
Periodically, you’ll find you’d like to weld intersecting or adjoining line segments into a single entity. Perhaps you’ve exploded another shape, intersected geometry, or drawn a complex profile. By welding individual edges, you’ll create a “Curve” entity, the SketchUp equivalent of a polyline. Curves have the following effects on your modeling:
- Curves are easier to select, group, and organize in your SketchUp model. For instance, welding a series of imported contour lines makes it much easier to select multiple contours with one selection window.
- Curves will create a smoothed face automatically when push/pulled.
Using curves as the basis for a Follow Me path will result in a 3D extrusion with both hidden and softened edges.
To weld edges, first select all the edges you want to join, then right click your selection and choose "Weld Edges". Open the Entity Info panel and you’ll see that your selection is no longer a number of edges, but a single Curve.
Splitting a face
To split a face, draw a line with starting and ending points on the face's edges. Here, notice how the lines drawn across on the cube create smaller faces within the larger ones.
Healing a face
If you remove the line or arc that divides a face, the two faces are healed back into one face. To remove a line or arc, select it, context-click, and choose Erase from the menu that appears. Or click the line or arc with the Eraser () tool. The figure shows how erasing the arc heals the right-hand face on the cube.
Exploding an entity
SketchUp is about making models, not destroying them. So why does it have an Explode feature?
When you draw a circle, arc, polygon, or curve entity, several segments make up the entity, but selecting any segment selects the whole entity. The explode feature breaks an entity into its segments, so that you can select one segment separately from the others.
To explode an entity, select it, context-click the selection, and choose Explode Curve from the menu that appears. In the figure, you see a polygon that’s about to explode into its individual segments.