488 Part V: On a 3D Spree

Grabbing the SteeringWheels

SteeringWheels act as a kind of navigation hub that allows you to access several different 2D and 3D navigation tools from a single user interface. (AutoCAD LT includes only the 2D Navigation wheel.) AutoCAD (the full version) comes with the 2D Navigation wheel and three other wheels that are designed to be used with 3D modeling. The three additional wheels are

View Object: Contains tools to center a model in the current view, zoom in and out, or orbit around a model.

Tour Building: Contains tools to move the viewpoint forward and backward, look around the model from a fixed location, and change the elevation of the current viewpoint.

Full Navigation: Contains a combination of the tools found on the 2D Navigation, View Object, and Tour Building wheels with the addition of tools to walk around or fly through a model.

All wheels include a Rewind tool, which allows you to restore a previous view.

The Rewind tool is similar to the Previous option of the ZOOM command.

When a wheel is active, move the cursor over the wedge that contains the tool you want to use. For many of the tools, you either click over the tool, or click and drag to use the tool. Some tools support alternate versions of themselves when you press and hold the Shift key. To get an idea of what each tool does, hover the cursor over the tool to display a tooltip message. To learn more about each of the wheels and the tools on them, see AutoCAD’s online help. To display the help specific to the wheels, right-click when a wheel is displayed and choose Help from the shortcut menu.

Visualizing 3D Objects

It really doesn’t seem like that long ago when the only way of viewing 3D models was wireframe mode, but the last several releases have dramatically improved AutoCAD’s visualization capabilities. There are almost a dozen different display modes — visual styles — that you can set with the click of a drop-down menu. Figure 21-7 shows the default visual styles — and you can add your own if you want — in the Visual Styles Manager palette.

Visual styles are collections of settings that build on the SHADEMODE settings found in earlier incarnations of AutoCAD. AutoCAD 2008 introduced five default visual styles, and that number doubled with AutoCAD 2011 to a total of ten:

2D Wireframe: AutoCAD’s classic 2D viewing mode: full wireframe, dotbased grid, the 2D UCS icon, and no perspective.

Conceptual: An illustrative kind of shaded view. Colors are unrealistic and edges are heavy, but you get a good sense of the model’s form. Figure 21-3 shows an example of the Conceptual visual style.

www.it-ebooks.info

Chapter 21: It’s a 3D World After All 489

Hidden: Looks slightly like a wireframe view (no surfaces are visible) but edges behind faces are hidden.

Realistic: Fully shaded, but not rendered visual style; edges are not displayed, and a default ambient lighting highlights the faces with different intensities of the object color. Materials and textures are visible if they’ve been applied. Have a look at Figure 12-8 for an example.

Shaded: Similar to Realistic, but with more subdued lighting. Textures do not appear in this visual style.

Shaded with Edges: Same as the Shaded visual style, except that isolines are set to be displayed.

Shades of Gray: Like Shaded, only all object colors are changed to different intensities of gray.

Sketchy: Visual style that does not apply any shading to the faces of 3D objects but give the edges of 3D objects a hand-sketched look. Somehow we’re not sure of the logic in spending several thousand dollars on hardware and software so you can produce something that looks hand sketched.

Wireframe: Pretty much the same as 2D wireframe, except for background color, optional perspective, and the 3D rather than the 2D UCS icon. Figure 21-4 shows a simple model in Wireframe visual style.

X-ray: Similar to Shaded with Edges, except that Materials and Textures are applied like the Realistic visual style and faces are set to 50% opacity.

AutoCAD 2013’s ten preconfigured visual styles are only the beginning. You can modify any of the styles or create new ones in the Visual Styles Manager palette (see Figure 21-8).

Figure 21-7: Some new styles to try on.

www.it-ebooks.info

490 Part V: On a 3D Spree

Figure 21-8: A manager for your visual styles.

To display the Visual Styles Manager, click the dialog box launcher (the little arrow at the right end of the panel label) on the Visual Styles panel of the View tab, or simply type VSM and press Enter.

www.it-ebooks.info

22

From Drawings to Models

In This Chapter

Escaping from the X, Y plane without a parachute

Understanding 3D pros and cons

Setting up a 3D working environment

Creating 3D solid geometry

Editing 3D models

For millennia, people have documented the design and construction of three-dimensional objects by drawing two-dimensional views of them.

Most people have continued to use these “classical” methods with CAD drafting because the methods are well understood and work reasonably well. After all, if 2D drawing was good enough for guys like Leonardo da Vinci and Andrea Palladio, it should be good enough for us, right?

Nonetheless, the past decade (or so) has seen a trend toward creating 3D CAD models and letting the software generate the 2D views more-or-less automatically. This approach seems more logical, especially

if the project documentation requires numerous, complex views of the same object. 3D modeling also is an absolute necessity when you want to create rendered views for presentation purposes.

And although AutoCAD 3D construction and visualization tools have improved dramatically over the years (trust us — you should have seen what they were like as recently as AutoCAD 2006!), it’s still a complex pro-

cess that requires sophistication on the part of the AutoCAD user. Although 3D modeling requires only one more dimension than 2D drafting, developing 3D CAD models can seem to be more

complicated. Users must master new techniques and contend with the 2D limitations of most display screens and input devices. On the other hand, after you have the 3D model, generation of traditional 2D drawing views is almost trivial.

www.it-ebooks.info

492 Part V: On a 3D Spree

In Chapter 21, we show you how to move around models that others have made, and explain the principles of 3D coordinate systems that you need to understand to work in AutoCAD’s 3D environment. This chapter introduces you to the concepts, tools, and techniques of AutoCAD 3D modeling itself; here, you can get your feet wet creating your own 3D objects.

Full 3D support is one of the main differences between full AutoCAD and AutoCAD LT. If you’re using AutoCAD LT, you can look at and plot 3D models created in AutoCAD, but you can’t do much 3D object creation or editing yourself. Also, viewing 3D models is less flexible in AutoCAD LT because it lacks nearly all the 3D navigation and rendering tools included in the full version of AutoCAD.

Is 3D for Me?

Traditional 2D drawings provide clues to help the viewer’s mind construct a 3D model from the 2D image on paper. Multiple views from different viewpoints in 3D space give experienced designers, drafters, and builders the information they need to make 3D sense of 2D drawings. Design and drafting

have succeeded pretty well by using 2D representations as the guide to creating 3D objects. But at some point, nothing can replace a true 3D model, such as in helping someone understand how a building will look when constructed or how two parts fit together.

What does using 3D in AutoCAD mean? Fundamentally, it means creating models instead of drawings. Rather than generate cross sections of an object or individual views of it from certain perspectives, you create a three-dimen- sional model of the object. This 3D depiction of each object includes all the necessary information for AutoCAD to create a drawing view from any point of view. With a properly constructed 3D model, AutoCAD can output commands to machines to create actual 3D objects, whether plastic prototypes carved from a tank of jelly by 3D printers, or an actual bolt, valve, or piston created by computer-controlled machine tools.

As we explain in Chapter 21, AutoCAD can create three types of 3D models: wireframe, surface, and solid. In most practical applications of 3D, you select one of these types for all or most of the objects in the drawing, based on ease of construction and intended use of the model. However, AutoCAD doesn’t prevent you from mixing all three types of 3D objects in the same drawing.

After you determine the type of 3D representation to use, you decide on the appropriate level of detail and construct the model, using the commands and techniques introduced in this chapter. If you need, you can go on from there to create any required 2D and/or rendered views for plotting or viewing onscreen.

www.it-ebooks.info