Chapter 6
IN THIS CHAPTER
Extruding around circles and along paths with Follow Me
Mastering the Scale tool
Creating 3D terrain with the Sandbox tools
Using the Solid Tools for additive and subtractive modeling
Here’s something you already know: There’s more to life than modeling buildings. Even though SketchUp is really good at letting you make models of built structures, you can use SketchUp to build just about anything you can imagine. All you need is time, ingenuity, and the ability to step back and break down things into their basic parts. SketchUp provides fantastic tools for creating forms that aren’t the least bit boxy, but those tools aren’t as obvious as Push/Pull and Rectangle, so most people never find them. This chapter is devoted to helping you discover SketchUp’s “rounder” side.
Another reason for pushing past basic boxes? Many people see 3D printing (sound of futuristic music and warp drives engaging) as the next vanguard of human innovation, and 3D modeling — like you do with SketchUp — is half of that equation. If you’re going to be printing your own bike helmets and vacuum cleaners in the next decade, you’d better get good at modeling organic shapes. (Chapter 9 offers an introduction to 3D printing with SketchUp.)
In this chapter, you discover tools, techniques, and other tips for creating forms that are distinctly unbuilding-like. Our hope is that you’ll use them to push the limits of what you think SketchUp can do.
Follow Me is probably the best example of a powerful SketchUp tool with kind of an underwhelming name. When the software designers were trying to figure out what to call their new baby, the problem that they faced was this: This tool does what other 3D modeling programs dedicate two or three other tools to doing. The designers chose an unconventional name because Follow Me is a wholly unconventional tool.
As shown in Figure 6-1, you can use Follow Me to create all sorts of shapes:
At its core, Follow Me lets you create forms that are extrusions. It’s a little bit like Push/Pull, except that it doesn’t just work in one direction. You tell Follow Me to follow a path, and it extrudes a face all along that path. So, you need three things to use Follow Me:
Follow these steps to use Follow Me; Figure 6-2 shows a basic example of how it works:
Draw a face to use as an extrusion profile.
In this example, you create a pipe, so the extrusion profile is a circular face.
Draw an edge (or edges) to use as an extrusion path.
Although the edge (or edges) is touching the face in this case, it doesn’t have to for Follow Me to work.
Select the complete extrusion path you want to use.
Check out the section on making selections in Chapter 3 for pointers on using the Select tool to best advantage.
Activate the Follow Me tool by choosing Tools ⇒ Follow Me.
To see Follow Me on your toolbar, select the Large Tool Set. On Windows, choose View ⇒ Toolbars, select the Large Tool Set check box in the dialog box that appears, and click Close. On a Mac, choose View ⇒ Tool Palettes ⇒ Large Tool Set.
Click the face you want to extrude.
Magic! Your face (extrusion profile) is extruded along the path you chose in Step 3, creating a 3D form (in this case, a section of pipe).
And nuclear power plant chimneys. A surprising number of things can be modeled by using Follow Me to perform a lathe operation. A lathe is a tool that carpenters (and machinists) use to spin a block of raw material while they carve into it — that’s how baseball bats are made (the good ones, anyway).
A simple example of a lathed object is a sphere. Here’s how you might make one with Follow Me:
Rotate a copy of your circle by 90 degrees, as shown in Figure 6-3.
If you’re wondering how to do this, follow these steps:
Still dragging, move your cursor to the endpoint on the exact opposite side of your circle; then release your mouse button.
Your axis of rotation is a line right through the center of your circle.
You can read all about the Rotate tool in Chapter 3.
With the Follow Me tool (choose Tools ⇒ Follow Me), click the circle that’s not selected, as shown in Figure 6-4.
Now you have a sphere. The Follow Me tool lathed your circular face around the path you selected — the other circle.
If you want to make your curved surfaces look smooth (hiding the edges between them), check out the sidebar “Smoothing those unsightly edges,” later in this chapter.
Under typical circumstances, you only have to model half a profile to use Follow Me to make it three-dimensional. Figure 6-5 shows a few examples of 3D objects created by using Follow Me.
A lot of the time, you want to use Follow Me to create geometry (edges and faces) that’s attached to another part of your model. An example of this may be modeling a gutter that runs all the way around the roof of your house. In this case, you already have the path along which you want to extrude a profile (the edge of the roof).
When you use Follow Me to extrude a face along a path that consists of edges that already exist as part of your model, always do two things:
Before using Follow Me, make the rest of your model a separate group. Take our word for it — Follow Me can sometimes mess up your model, so keep the geometry Follow Me creates separate, just in case.
Make a copy of your extrusion path outside your group. There’s a consequence to working with Follow Me on top of a group: The edge (or edges) you want to use as an extrusion path aren’t available because you can’t use Follow Me with a path that’s in a separate group or component.
What to do? You need to make a copy of the path outside the group and then use the copy to do the Follow Me operation. Here’s the best way to make a copy of the path:
Choose Edit ⇒ Paste in Place.
You have a copy of the path you want to use, and it’s outside your group.
When you use an existing edge (or series of edges) as an extrusion path, the hard part is getting your profile in the right place. You can proceed in two ways; which one you choose depends on what you need to model:
Consider that you have a model of a house. You want to use Follow Me to add a gutter that goes all the way around the perimeter of the roof. You decide to draw the profile in place (right on the roof itself) because the edges of the roof are drawn parallel to the colored drawing axes. This means that you’ll have an easier time using the Line tool to draw in midair.
The trick to drawing an extrusion profile that isn’t on the ground is to start by drawing a rectangular face. You then draw the profile on the face and erase the rest of the rectangle. Figure 6-6 shows how you’d draw the profile of a gutter directly on the corner of a roof; the steps that follow explain the same things in words:
Zoom in on what you’re doing.
Many people try to work without filling their modeling windows with the subject at hand. Not doing so is like trying to do a crossword puzzle while looking the wrong way through a pair of binoculars. Get close — SketchUp models don’t bite!
Using the Line tool, draw a rectangle whose face is perpendicular to the edge you want to use for Follow Me.
Pay careful attention to SketchUp’s inference engine, introduced in Chapter 3. Watch the colors to make sure that you’re drawing in the right direction.
Use the Line tool (and SketchUp’s other drawing tools) to draw your profile directly on the rectangle you just drew.
The important thing here is to make sure that your extrusion profile is a single face; if it’s not, Follow Me won’t work the way you want it to.
The awful thing about handrails is that they’re almost always at funny angles, not parallel to a colored axis. When drawing your extrusion profile in place isn’t convenient, draw it on the ground and move it into position after.
Here’s the trick: Draw a tail — a short edge — perpendicular to your extrusion profile. This tail helps you line up your profile with the edge that you want to use as an extrusion path for Follow Me. The following steps and Figure 6-7 describe how you’d draw and position a profile for a handrail:
Draw a short edge perpendicular to the face you just drew.
This tail should come from the point where you want your profile to attach to the extrusion path.
Make your profile and its tail into a group.
This makes it easier to move and rotate around all at once. See Chapter 5 for information on creating and using groups.
Using the Move tool, place your profile at the end of the extrusion path.
To make sure that you position your profile accurately, pick it up by clicking the point where the tail meets the face and then drop it by clicking the end of the extrusion path.
With the Rotate tool, rotate your profile into position.
Here’s where you need to use a bit of skill. (See Chapter 3 for guidance.) The Rotate tool is easy to use — after you get the hang of it.
What if you want to model a bar of soap? Or a sofa cushion? Or anything that doesn’t have a sharp edge? The best way to round off edges in SketchUp is to use Follow Me. In addition to using Follow Me to add to your model, you can also subtract from your model.
Here’s how it works: If you draw an extrusion profile on the end face of a longish form, you can use Follow Me to remove a strip of material along whatever path you specify. Figure 6-8 demonstrates the concept on the top of a box.
But what if you want to create a corner that’s rounded in both directions, as so many corners are? That one’s a little trickier to do. The basic technique involves using Follow Me on a corner you’ve already rounded with the Push/Pull tool. After you round a corner with an arc of the correct radius, you can use copies (or component instances, if you’re clever) of that corner several times, wherever you need them. Although we wouldn’t call this solution elegant, it works.
Figure 6-9 gives a step-by-step, visual account of the process, while the following steps explain it in words, as follows:
Draw a box.
The box should be big enough for the round you want to apply.
With the 2 Point Arc tool, draw an arc on the corner of the box.
When you’re drawing an arc on a corner, keep an eye out for the inferences that help you draw properly:
Reduce the number of sides on your arc before you start rounding away. See the sidebar “Why your computer is so slow,” earlier in this chapter, to find out why.
Draw another identical arc on one of the corners directly adjacent to the corner you just rounded.
This is where you refer to Figure 6-9. Pictures are better than words when explaining things like adjacent corners.
Hide or smooth any edges that need it.
For information about hiding edges, see Chapter 5. Check out this chapter’s “Smoothing those unsightly edges” sidebar for the whole scoop on how to smooth edges.
After you have a fully rounded corner, you can use a bunch of them to make anything you want; it just takes a little planning. Figure 6-10 shows a simple bar of soap created out of eight rounded corners, copied, and flipped accordingly. The text (in case you’re wondering) was created with SketchUp’s 3D Text tool, which you can find on the Tools menu.
Real heroes are rarely obvious. The Scale tool is the single most misunderstood member of SketchUp’s mercifully limited toolkit. New modelers assume that Scale is for resizing things in your model. That’s technically true, but most folks only use it to resize whole objects; the real power of Scale happens when you use it on parts of objects to change their shape. Figure 6-11 illustrates how Scale can distort basic shapes into more complex ones.
The basic principle of this technique is pretty simple: You select the geometry (edges and faces) in your model that you want to resize, activate the Scale tool, and go to town.
Here’s a list of steps, just so it’s crystal clear. Figure 6-12 tells the story in pictures:
Select the part of your model that you want to scale.
Use the Select tool to do this; check out Chapter 3 for details about making selections.
Activate the Scale tool by choosing Tools ⇒ Scale.
You can also make Scale active by clicking its button on the toolbar or by pressing the S key on your keyboard. After you activate Scale, the geometry you selected in Step 1 should be enclosed in a box of little green cubes, or grips.
Click a grip and then move your mouse to start scaling your selected geometry.
Keep reading for the lowdown on the different grips.
While we're on the subject of Scale, here are a few more things you should know:
You can’t make a copy while you scale. Both the Move and Rotate tools let you make copies by holding down a button on your keyboard while you’re using them, but Scale doesn’t work this way. If you need to make a scaled copy, try this instead:
Select the geometry that you want to scale and copy, and then make it into a group.
See Chapter 5 for more information on making groups.
Here’s where it gets really interesting. We need to thank über-SketchUpper Justin Chin (who goes by the handle monsterzero online) for demonstrating the power of scaling profiles to make organic forms. The method is great because it’s easy to understand and powerful enough to be applied all over the place.
So what is this method? You use the Scale tool in combination with a series of 2D profiles to create curvy, lumpy, distinctly un-boxy 3D shapes. An awful lot of the stuff in the universe fits squarely in this category: us, you, slugs, intergalactic alien fighter vessels, bananas — just about everything that wasn’t made by a machine can be modeled using the scaled profiles method of 3D modeling.
The simplest way to use this method is in association with Push/Pull. Here’s a very simple example of how it works. Check out Figure 6-14 for an illustrated view:
Create a 2D shape.
This shape may be something simple (such as a circle) or something more complex; it all depends on what you’re trying to model. The shape may also be a half-shape if what you’re trying to make exhibits bilateral symmetry. Take a look at the last section in Chapter 5 for more information on using components to build symmetrical models.
Scale the new face you created so it’s slightly bigger (or slightly smaller) than the original 2D shape from Step 1.
See the previous section in this chapter for more specifics about using the Scale tool. Pay special attention to the points about using modifier keys, or keyboard buttons, to scale proportionally or about the center of what you’re working on.
Push/pull the face you scaled in the preceding step.
Try to make this extrusion about the same as the one you made in Step 2.
You can usually double-click a face with the Push/Pull tool to repeat the last Push/Pull operation you did.
Repeat Steps 3 and 4 until you’re done.
You can add skillful use of the Rotate tool into the mix if you like; doing so allows you to curve and bend your form as you shape it.
Keep the following tidbits in mind as you explore this technique:
Another way to create extruded forms is to use Follow Me. (See the first part of this chapter if you need a refresher.) This technique is ideally suited to making long, curvy, tapered things like tentacles and antlers; it’s a little time-consuming but works like a charm.
Modeling a simplified bull’s horn is a good, straightforward illustration of how the Follow Me variation of this method works. Here’s how to go about it; take a look at Figure 6-16 to see the story in pictures:
Draw a circle.
This is the extrusion profile for Follow Me. Strongly consider reducing the number of sides in your circle from the standard 24 to something more like 10 or 12. See the sidebar “Why your computer is so slow” (earlier in this chapter) to find out how and why you should do this.
Draw a 10-sided arc that starts perpendicular to the center of the circle you drew in Step 1.
Type 10s and press Enter right after you click to finish drawing your arc.
This tells SketchUp to make sure your arc has 10 sides (instead of the default 12). Why 10 sides? It makes the math easier a few steps from now.
The easiest way to create a halfway-accurate arc in 3D space is to start by drawing a rectangle. When you’re sure this rectangle is properly situated, use one of the arc tools to draw on top of the rectangle and then delete everything but the arc.
Select the arc you just drew.
This is the extrusion path for Follow Me.
Choose View ⇒ Hidden Geometry from the menu bar.
Showing the hidden geometry in your model lets you select the edges that were automatically smoothed (made hidden) when you used Follow Me in Step 4.
Scale the face at the end of your new extrusion by a factor of 0.1.
See “Getting the hang of Scale,” earlier in this chapter, for instructions on how to do this. Use any of the four corner grips on the scaling box, and don’t forget to hold down the Ctrl key (Option on a Mac) while you’re scaling — this forces SketchUp to scale about the center of the face you’re resizing.
Select the edges that define the next-to-last profile in your extruded form.
Depending on the angle of your arc, making this selection can get tricky. Here are some tips that may help:
Scale the edges you selected in the preceding step by a factor of 0.2.
Starting to see what’s happening?
Repeat Steps 8 and 9 for each of the remaining profiles in your form, increasing the scaling factor by 0.1 each time.
Of course, you can absolutely choose to sculpt your form however you like, but this method (counting up by tenths) yields a smooth taper.
The Santa-Claus-and-reindeer project illustrates the kind of fancy, not-a-box models you can build after you master the Scale tool. It’s not beginner-level material, but it’s worth the time when you’re ready.
Continuing in the grand tradition of building extremely powerful tools and then hiding them so you’ll never find them, the people at SketchUp introduced the Sandbox way back in version 5 of the software. We introduce the Sandbox here because it helps people to model terrain — the stuff your buildings sit on (or in, if what you’re making is underground).
The Sandbox isn’t new, but owing to its less-than-obvious location, most SketchUp users have never used it. Here are the facts:
The Sandbox is hidden. The reasons for this are complicated, but the tools in the Sandbox are a little bit special; they’re extensions — you have to find them and turn them on before you can use them. If you’re using SketchUp Pro, you can skip the first two steps in the following list — they’re already turned on.
Follow these steps to switch on the Sandbox tools:
Choose Window ⇒ Preferences from the menu bar to open the Preferences dialog box.
Choose SketchUp ⇒ Preferences if you’re on a Mac.
Whether you’re modeling a patch of ground for a building or redesigning Central Park, you need one of two terrain-modeling methods:
You know the squiggly lines on topographical maps that show you where the hills and valleys are? They’re contour lines (or contours) because they represent the contours of the terrain; every point on a single line is the same height above sea level as every other point on that line. Where the lines are close together, the ground between them is steep. Where the lines are far apart, the slope is less steep. Cartographers, surveyors, engineers, and architects use contour lines to represent 3D terrain in flat formats like maps and site drawings.
Sometimes, you have contour lines for a building site that you want to model in 3D. You can use the From Contours tool in the Sandbox to automatically generate a three-dimensional surface from a set of contour lines, as shown in Figure 6-17.
Here are some things to keep in mind about the From Contours tool:
It’s a two-step tool. Using From Contours is simple after you get the hang of it:
Note: If you can’t see the Sandbox tools in your menus, you haven’t turned them on yet. See the beginning of this section, “Making and Modifying Terrain,” to rectify the situation.
You end up with a group. When you use From Contours, SketchUp automatically makes your new surface (the one you generated from your contour lines) into a group. It leaves the original lines themselves completely alone; you can move them away, hide them, or delete them if you want. We recommend making another group out of them, putting them on a separate layer (see Chapter 7 for more on this), and hiding that layer until you need it again.
To edit the faces and edges inside a group, double-click it with the Select tool. Chapter 5 has all the details on groups and components.
Without contour lines that define the shape of the terrain you want to model, you have to start with a level surface. Use the From Scratch tool to create a big, flat rectangle that represents a chunk of ground. Because the rectangle is already divided into triangular faces, it’s easy to use the Smoove tool (discussed next in this chapter) to shape the rectangle into hills, valleys, sand traps, and whatever else you have in mind.
Here’s the thing, though: It’s a very rare occasion that you have carte blanche with a piece of land. Unless you design something like a golf course in the middle of a dry lake bed or terraform a new planet for colonization, you probably have preexisting terrain conditions to contend with. And if that’s the case, you’re probably better starting off with a set of contour lines that describe those conditions, as discussed earlier in this chapter.
So although the From Scratch Tool works great, you probably won't need to use it much. All the same, here’s how to do so, just in case.
Follow these steps to create a new terrain surface with the From Scratch tool and take a look at Figure 6-19 while you’re at it:
Type a grid spacing amount and press Enter.
The default grid spacing amount is 10 feet, which means the tool draws a rectangle made up of squares that are 10 feet across. The grid spacing you choose depends on how big an area you’re planning to model and how detailed you plan to make the terrain for that model.
If Aidan were modeling a single-family house on a reasonably sized lot, he would probably use a grid spacing of 2 feet — that’d provide enough detail for elements like walkways and small berms without creating too much geometry for a computer to handle. If he were laying out an 18-hole golf course, on the other hand, he'd choose a grid spacing closer to 50 feet and then add detail to certain areas later.
Click to establish the length of your new terrain surface.
When you’re done, the great big rectangle you’ve created will automatically be a group. Double-click with the Select tool to edit it and get started. You’ll probably decide to use the Smoove tool next; jump ahead to “Making freeform hills and valleys with Smoove” (later in this chapter) to find out how.
Perhaps you want to model a smallish chunk of nonflat terrain that surrounds a building. Maybe you’re trying to reproduce existing site conditions, or maybe you’re in the process of designing the landscape for a project. There’s a neat technique for cases like this one: You can use From Contours to quickly generate a surface from just a few simple outlines.
Follow these steps to model a simple terrain surface with the From Contours tool, as shown in Figure 6-20:
Make your building into a group.
See Chapter 5 if you need help.
Use the Tape Measure and Line tools to draw the outline of the chunk of terrain you want to model around the building.
Keep in mind that the resulting horizontal face is flat; just pretend you’re drawing in 2D space. It doesn’t matter if the outline you draw is below, above, or in line with the building, as you see in the next step.
Paint the walls of your box with a translucent material.
You can find some in the Translucent library, in the Materials panel. See Chapters 2 and 3 for help.
Take a look at the section “Modeling terrain from scratch” for tips on using From Contours; at this point, you need to use the Flip Edge tool and the Eraser to clean up your terrain model — particularly where your building is supposed to go.
No matter how you make a terrain model, there’s a 99-percent chance that it consists of lots and lots of triangles. Switch on Hidden Geometry (choose View ⇒ Hidden Geometry) to see them. As long as you have triangles, you can use the Sandbox’s terrain editing tools. This section shows you how to do the following:
Smoove is a tool for moving smoothly — get it? Smooth + Move = Smoove. We’ll wait while you compose yourself.
Smoove is actually one of the coolest tools in SketchUp; it lets you shape terrain (or any horizontal surface that’s made up of smaller, triangular faces) by pushing and pulling (sort of) bumps and depressions of any size. Smoove is fun to use and yields results that you’d be hard-pressed to produce with any other tool in SketchUp. Figure 6-21 shows what Smoove can do.
Follow these steps to shape a surface with Smoove:
Double-click the group containing your terrain to edit it.
If your terrain isn’t part of a group, forget this step.
Type a radius and press Enter.
Smoove creates lumps, bumps, and dimples that are circular. The radius you enter here determines how big those lumps, bumps, and dimples should be.
Fun, huh? Here are some more things to keep in mind when you use Smoove:
Eventually, you may need to plunk down a building (or some other structure) on the terrain you’ve lovingly crafted. The Stamp tool provides an easy way to — you guessed it — stamp a building footprint into a terrain surface, creating a flat “pad” for something to sit on. This tool also provides a way to create a gently sloping offset around the perimeter of your stamped form. This creates a smoother transition between the new, flat pad and the existing terrain.
Follow these steps to use the Stamp tool; check out Figure 6-23 to see the corresponding pictures:
Move the building you want to stamp into position above your terrain surface.
The building shouldn’t touch the terrain but float in space directly above it. Also, turn the building into a group before you start moving anything; take a look at Chapter 5 to find out all about groups and components.
If you’re having trouble moving your building into position accurately, move it to the correct height first and then switch to a top, no-perspective view to finish the job. Look in the Camera menu for both these commands.
Type an offset distance and press Enter.
The offset distance is the amount of space around the perimeter of whatever you’re stamping that SketchUp uses to smooth the transition between the flat spot it’s creating and the existing terrain. The offset amount you choose depends entirely on what you’re stamping. Go nuts, and thank your lucky stars for Undo.
Here are a couple things that are handy to know when you use Stamp:
The Drape tool works a little like a cookie cutter; use it to transfer edges from an object down onto another surface, which is directly beneath it.
Perhaps you have a gently sloping terrain and you want to draw a meandering path on it. The path has to follow the contours of the terrain, but because you want to paint it with a different material, it needs to be a separate face. In this case, you’d draw the path on a separate face and use the Drape tool to transfer it to your terrain surface.
Taking the preceding example, follow these steps to use the Drape tool to draw a path on a nonflat terrain surface. Figure 6-24 illustrates the steps:
Use the Line tool (see Chapter 2) to draw a flat face somewhere directly above your terrain surface.
If you can, make your flat face exactly the same size as your terrain. Just make sure it’s big enough for whatever you plan to draw next (in this example, a path).
Paint the face you just created with a translucent material.
I find that a light gray works well; there’s a good one in the Translucent library, inside the Materials panel.
Use the Line tool to carry up any important points on your terrain surface.
In this case, make sure the path begins precisely at the door of the building, so draw vertical lines from the sides of the door to the flat face directly above. That way, you have something to inference to in Step 6.
On the upper face, draw the edges you want to drape.
Make sure that your edges form closed loops to create faces. If they don’t, you’ll have a miserable time trying to paint the path (in this case) after it’s draped onto your terrain surface.
Soften/smooth the edges of the triangles in your terrain surface (if they aren’t already).
To do this, follow these steps:
Select the edges you want to drape.
If your edges define closed faces, you can select those faces instead; sometimes that’s easier than selecting a bunch of individual edges. Take a look at Chapter 3 for tips on selecting things.
Click once on your terrain surface to drape the edges you selected in Step 9.
It doesn’t matter if your terrain is inside a group — the Drape tool works anyway.
So-called solid modeling operations (fancy people refer to them as Boolean operations) give you the ability to create the shapes you need by adding or subtracting other shapes to or from each other. In the next few pages, you discover how to use all six of SketchUp Pro’s Solid Tools, giving detailed examples for the three that are the most useful.
TABLE 6-1 The Solid Tools
Tool |
What It Does and How to Use It |
Start With |
End With |
Union |
What: Combines two or more solids into a single solid. Deletes overlapping geometry. Preserves internal pockets.* How: Select the solids you want to use and then activate the tool. |
Two+ solids |
One solid |
Outer Shell |
What: Combines two or more solids into a single solid. Deletes overlapping geometry, including internal pockets.* How: as Union tool. |
Two+ solids |
One solid |
Intersect |
What: Makes a single solid in which two or more solids overlap. Deletes everything else. How: Same as Union tool. |
Two+ solids |
One solid |
Subtract |
What: Uses one solid to cut away part of another solid. Deletes the first solid when it’s done. How: Activate the tool, click “cutting” solid, and then click solid to be cut. |
Two solids |
One solid |
Trim |
What: Uses one solid to cut away part of another solid. Keeps what’s left of both solids. How: Same as Subtract tool. |
Two solids |
Two solids |
Split |
What: Cuts two solids where they overlap and creates a new solid from the overlap. Doesn’t delete anything. How: Same as Union tool. |
Two solids |
Three solids |
* An internal pocket is like a solid within a solid — it’s a completely enclosed volume that happens to be located inside the main volume of a solid. Picture a SketchUp model of a tennis ball. Because tennis balls have a thickness, you’d need two surfaces to model one: one for the inside, and one for the outside. If you selected both and made a group, you’d have a solid with an internal pocket inside.
Before you can use the Solid Tools, you need solids. Here are six things you need to know about solids; you can think of them as the Solid Rules:
No extra edges or faces allowed. You wouldn’t think that one or two edges or faces would make much of a difference, but it does — solids can’t contain any extra geometry, period. Figure 6-25 shows some examples of things that can disqualify otherwise completely enclosed shapes from being solids.
A few SketchUp extensions make it easier to figure out why a particular group or component isn’t solid. For starters, check out Solid Inspector2 by ThomThom. For an introduction to the Extension Warehouse, see Chapter 16.
Solids can be made up of multiple shapes. This one is confusing at first. As long as each individual cluster of geometry within a group or component is completely enclosed, SketchUp considers that group or component to be a solid. It doesn’t matter that they’re not connected or touching in any way; what’s important is that an area of space is fully surrounded by faces.
When you have a solid object or objects, you can use SketchUp’s Solid Tools in powerful ways to create shapes that’d otherwise be very complicated and time-consuming to make. For example:
Two things you need to know before you start using the Solid Tools:
To use the Solid Tools, preselect — or don’t. Pick the tool you want to use either before or after you’ve told SketchUp which solid objects you want to affect. Like most “order of operations” issues (are you listening, Follow Me tool?), this can be confusing for some folks.
The easiest way to use the Solid Tools is to preselect the solids and then choose the tool to carry out the operation. The glaring exceptions to this rule are the Subtract and Trim tools; both of these depend heavily on the order in which you pick your solids. Take a peek at Table 6-1 for more specifics.
Without further ado, here’s Table 6-1 with a rundown of the Solid Tools. (Check out Figure 6-27 for a visual.)
In this section, you find a few examples of everyday modeling challenges that the Solid Tools can help make less challenging. You’re almost certain to encounter these tricky situations while you climb the ladder toward ultimate SketchUp ninjahood.
Chapter 4 has a section about using the Intersect Faces tool to combine multiple roof pitches into a single, solitary roof. If all those gables, hips, dormers, and other roof elements are solids, you can absolutely use SketchUp’s Union or Outer Shell tools to make quick work of the problem.
The same goes for anything that’s composed of several disparate elements that you’ve assembled by moving them together until they overlap. In the spacecraft in Figure 6-28, the hull (or body) combines different pieces. Notice the lack of edges where the components intersect? We think edges add detail and definition, especially when a model is displayed using a lines-only style (as it is here). There’s also the issue of all the geometry hidden inside the hull. Combining everything together into a single solid helps it shed weight and look better, all at the same time.
Anyone who’s ever tried to model a car with SketchUp knows it’s a tricky undertaking. The problem is that cars (and most other vehicles) are kind of curvy; worse yet, they’re curvy in several directions.
One trick lots of modelers use to block out a basic shape for things like cars is to start with orthographic — straight-on top, front, and side — views of the thing they’re trying to model. Here’s how the method works:
This method doesn’t always produce perfect results, but it’s a lot better than guessing. Plus, it’s fun. Figure 6-29 shows the technique in action.
Woodworkers and industrial designers, take heed: SketchUp Pro’s Trim tool saves you literally hours of work. Anytime you need to build a model with parts that interlock or otherwise fit together closely, Trim is where you should look first.
Trim basically tells one part to “take a bite” out of another, which is perfect for joinery (dovetails, finger joints, dadoes, and so on), machine parts, ball-and-socket joints, and any other positive/negative conditions where two parts meet.
Figure 6-30 shows how to build a small wooden box with dovetailed sides and a dadoed bottom.
Choose Tools ⇒ Solid Tools ⇒ Trim to activate the Trim tool.
Your cursor has the number 1 on it.
Select the box bottom.
Your cursor changes to show the number 2.
Select one side on the box.
You just cut a dado using the box bottom you picked in Step 2. Your cursor still says 2.
Select the remaining two sides to cut dadoes in them, too.
Fun!
Here’s the thing: As soon as you use a Solid Tool on a component instance, SketchUp makes that instance unique; it’s still a component — it just isn’t connected to the other instances anymore.