Inferring Edges
Many times when you’re drawing edges, you want to draw one edge parallel to another and end so you can connect the two edges with another edge that goes from end point to end point while the new edge is parallel to an axis. For example, take a look at the situation in Figure 2.21.
FIGURE 2.21 The need for inferring an edge.
There are two edges there—now suppose you want to draw a third edge on your way to making a rectangle. The third edge will be at the bottom of the figure, parallel to the top edge.
But how far should you draw the bottom edge so that its end point will be directly under the corresponding end point of the top edge? You can guess visually where to stop drawing the third edge so that its end point will end up right under the top edge’s end point, but SketchUp provides you with a better way.
Because this is such a common operation—ending an edge at the correct location to match another edge’s end point—SketchUp has a special name for it: inferring. When you infer an edge, you align it with another edge so that its end point is ready to be connected to another edge’s end point with a new edge that is parallel to an axis.
Here’s how inferring works, making it easy to draw figures so that all edges line up with axes:
1. Click the Start Using SketchUp button. SketchUp starts with the Engineering–Feet template we selected as the default in previous tasks. Click the human figure that appears in the template to select it, and press the Del key to delete it.
2. Click the Line tool to select it.
3. Draw two edges like those in Figure 2.21.
4. Draw a new edge from the end point of the vertical edge until a dotted line appears connecting the new edge and the top edge, as shown in Figure 2.22. That dotted line appears automatically as SketchUp infers you might want to line up the current edge’s end point with the end point of the top edge.
FIGURE 2.22 Inferring an edge.
5. If no dotted line appears, indicate to SketchUp which edge you want it to infer from by letting the mouse pointer hover over the top edge for two seconds. This establishes which edge you want to infer from, in case SketchUp doesn’t guess right. After letting the mouse hover over the edge you want to infer from for two seconds, redraw the third edge, and the dotted line connecting the end points should appear.
6. Release the mouse button to draw the third edge, as shown in Figure 2.23.
FIGURE 2.23 A new edge.
Now you’re in a good position to complete the figure and create a surface (because all edges are in the same plane). To complete the surface, just connect the end points of the top and bottom edges—thanks to inferring, their end points are already lined up.
When you connect the last two end points, SketchUp realizes you’ve created a surface and colors it in as a surface, as you can see in Figure 2.24.
In the next lesson, we’ll start drawing shapes in SketchUp.
FIGURE 2.24 A new surface.
Thanks :
Steven Holzner,
SamsTeachYourself Google SketchUp 8 in 10 Minutes
