TIEBIAOJI SketchUp Tutorials

Referencing a Sloped Surface

The first box you drew now has a handsome sloped roof. Suppose you want to create a sloped roof for the second box that continues along the same angle. You can draw this line the hard way, the inaccurate way, or the easy way. The hard way is to pull out SketchUp's protractor tool (see page 283) and to create a guideline that you use to create the new roofline. Well, that's not too hard, but it takes unnecessary steps and clicks. The inaccurate way is to change to a side view and just try to eyeball your roofline. You can get close, but it's unlikely you'll draw a truly accurate line. Creating your roofline the easy way takes only two clicks and a hover. Here are the steps:

Figure 4-5:

Draw the second vertical line using the click-move-click method. Press and hold Shift to lock the line to the blue axis. Reference the top of the first line (as shown here) to set the height of the second line.

Figure 4-5:

Draw the second vertical line using the click-move-click method. Press and hold Shift to lock the line to the blue axis. Reference the top of the first line (as shown here) to set the height of the second line.

1. With the Line (L) tool, click the point where your two boxes meet at the top.

A rubber band line appears, attached to the end of the Line cursor on one end and to the corner point on the other.

2. Move the cursor over the sloping line above the first box and hover along the edge.

Don't click or do anything else; you're just expressing your interest in the angled line. SketchUp takes note when you hover over an edge or face.

3. Move your cursor to extend that line across the vertical face of the second box, as shown in Figure 4-6.

When the line is at about the same slope as the roof line, it changes to a magenta color. This inference shows that the slope of the new line is identical to the line you hovered over in step 2. You can think of magenta as the parallel inference color.

4. Press and hold Shift to lock the inference.

The thin magenta line turns into a thick magenta line. You can move your line cursor anywhere in the window, and the line stays locked to the roof's slope. You lock the inference to the sloped line with the Shift key, just as you locked inferences that followed the main axes.

5. Click the box's right edge to finish the line.

Continue to hold Shift, and click any point along the right edge to complete the line.

Hover over sloped edge

Figure 4-6:

After hovering over the edge of the sloped roof, the Line tool displays a magenta inference line that shows the continuation of the slope. Press and hold Shift to lock in the inference and to complete the line.

Magenta inference line

Hover over sloped edge

Figure 4-6:

After hovering over the edge of the sloped roof, the Line tool displays a magenta inference line that shows the continuation of the slope. Press and hold Shift to lock in the inference and to complete the line.

Magenta inference line

6. Use the Push/Pull tool to remove the portion of the box above the roofline, as shown in Figure 4-7.

Start by clicking the upper triangle, and then click on the back edge of the box to reference the back face. When you click the back face, the excess portion disappears as it's pushed out of existence.

It was easy to match the slope of the original roofline by using the magenta inference. You'd already drawn that second box, so it was simple to determine the endpoint for your new sloped roof. But what if you wanted to create a new 3-D shape by using that same slope? Perhaps you'd like to continue this roofline all the way to the ground. SketchUp gives you an easy way to figure out the dimensions of this new addition.

1. Click the house's bottom corner, and then drag a line along the green axis.

When the line is oriented to the green axis, its color changes from black to green.

2. Press and hold Shift to lock the green inference line.

Holding the Shift key locks the line to the green axis and changes it to a thick green line. Now you can move the Line cursor to any point in the drawing window without changing the line's orientation.

3. Move the Line tool to the surface of the roof and then click.

Make sure your cursor is over the face of the sloped roof (as shown in Figure 4-8). When you click, SketchUp creates a line that's the perfect length to extend the slope of the roof to the ground.

Figure 4-7:

After creating the new slope line for the second roof, use the Push/Pull tool to push away the excess portion. Click and start your push, and then click the back edge of the box to remove the section entirely.

Figure 4-7:

After creating the new slope line for the second roof, use the Push/Pull tool to push away the excess portion. Click and start your push, and then click the back edge of the box to remove the section entirely.

Figure 4-8:

By referencing the slope of the roof, you can draw a line exactly the right length to extend the roof to the ground. To reference the slope, make sure your tool is over the face of the roof (as shown here), not over one of its edges.

Figure 4-8:

By referencing the slope of the roof, you can draw a line exactly the right length to extend the roof to the ground. To reference the slope, make sure your tool is over the face of the roof (as shown here), not over one of its edges.

4. Click the corner of the roofline to complete the new triangle.

If you want to examine the new triangle you created, use the Orbit (O) tool. Inspection shows that it's a perfect extension of the other rooflines.

5. Draw a line along the red axis, using the back of the box as a reference point.

Use Shift to lock this new line to the red axis, and then click the house's back edge to determine its length.

6. Draw a line to connect to the bottom of the box.

SketchUp is ready to draw a new line, so all you have to do is click the corner.

7. Draw a sloping line to complete the back triangle and enclose the new 3-D shape.

When you draw the last line (Figure 4-9), the top face forming the roof fills in, and the new addition is complete.

By now you're probably confident that as long as you have a sloped edge or face to reference, you can create a matching slope for any circumstance. That's true, but for the sake of complete disclosure, here's one more example. If you're following along doing the examples in SketchUp, use the Eraser tool to remove the addition you built in the last example. (For a tip on erasing several edges at once, see the box on the next page.)

In the previous example, you saw how to extend a line to just the right length to continue the slope of the roof. You can also use an inference to create a vertical line that's just the right height to continue the roof. As shown in Figure 4-10, the method is almost exactly the same. Click to start drawing a vertical line. When the line is blue, indicating it's aligned with the blue axis, press and hold Shift to lock in the inference. Then you can move your cursor to reference any point, edge, or face

Figure 4-9:

When you draw the last line, the last two faces of the new addition fill in.

Figure 4-9:

When you draw the last line, the last two faces of the new addition fill in.

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