Modifying 3D solids is trickier. Simple editing commands like Move, CoPy, and ROtate work fine, but most of the commands that alter an object’s shape (for example, Stretch, Trim, and Break) don’t work on solids. You can use grips to move and copy solids, but not to stretch them.
Instead, AutoCAD provides a set of specialized commands on the Modify>Solids Editing menu, shown in Figure 8-11. The first three choices — Union, Subtract, and Intersect — perform the so-called
Figure 8-11: Specialized solids editing commands.
Ending with Rendering
To my mother, who grew up on a farm in Iowa, rendering was what you did to fat to make it into lard. But in CAD, rendering is the process of illuminating a set of 3D objects with one or more imaginary lights and then creating a more-or-less realistic picture of the results. (No, computer programmers didn’t have lard on their minds when they borrowed the word
A single example of this technique is called a
AutoCAD creates still renderings only. If you want to create animations, you need to use other software programs such as Discreet’s 3DS Max. Even if you use animation programs, AutoCAD can be useful for developing the initial 3D models.
Rendering has steadily improved in speed and usability as PCs have become faster, and programmers have improved their rendering algorithms. Rendering of simple scenes is now practical on a mainstream PC, and a fast personal computer can create some impressive images in a reasonable amount of time. Rendered images are useful for previewing how your models will work in real life and also can be powerful tools for sales and marketing communications for your company. A (rendered) picture can be worth quite a bit more than a thousand words.
To see how rendering works with the default options in AutoCAD, use the steps that follow. When you’re ready to get fancy, choose User’s Guide>Create Realistic Images and Graphics>Render 3D Objects for Realism in the AutoCAD online help system.
1. Create one or more 3D objects.
Use the steps in the previous section or use one of the sample 3D drawings in Program Files AutoCAD 2005Sample.
Unless you want a monochromatic rendering, create the objects on several different layers that you’ve assigned different colors.
2. Choose View>Render>Render.
The Render dialog box appears, as shown in Figure 8-12.
Figure 8-12: The Render dialog box and a rendered object.
3. Ignore all the options and click the Render button.
You can get okay results without changing the options. When you click Render, AutoCAD renders the 3D objects. See Figure 8-12 for an example.
To make rendered images look less cartoonish, you need to apply materials to 3D objects and define different light sources. For more information, navigate to the Render 3D Objects for Realism help page mentioned just before the preceding steps and then look at Create Rendered Images>Use Materials in Rendering and Create Rendered Images>Use Lights in Rendering.
The SHADE command offers a simpler alternative to the RENDER command, without all the lighting, surface materials, and other options. To experiment with shading, choose any of the options on the View>Shade menu. (To return to an unshaded view, choose View>Shade>2D Wireframe.) As I mention earlier in this chapter, the 3DOrbit command’s right-click menu includes shaded modes that you can see even while navigating around your model in real time.
In addition to viewing rendered and shaded views on the screen, you can plot them, whether they’re in a paper space layout or in model space. Use the Shaded Viewport Options area of the expanded Plot dialog box to control this feature. Chapter 12 contains more information about plotting.
If you want to plot multiple rendered views (or a rendered view plus other nonrendered views), create a paper space layout with multiple viewports, as described in Chapter 3. As I mention earlier in this chapter, tiled model space viewports are great for creating and viewing 3D models, but you can plot only one model space viewport at a time. Use paper space layouts to compose multiple viewports for plotting purposes.
People who do a lot of rendering and want higher quality, photorealistic results usually use programs other than AutoCAD to render their models. Discreet 3DS Max, Autodesk VIZ, and McNeel’s are three popular photorealistic rendering programs. Most rendering programs can import 3D models from AutoCAD DWG files, but some people use specialized 3D modeling programs to do their modeling as well.
Part III
If Drawings Could Talk
Text, dimensions, and hatching have long been important clarifying elements in drafting. In AutoCAD, these elements are flexible almost to a fault, and you can edit and update them quickly as you change the geometry beneath them. The text, dimension, and hatching annotations that you add “speak” about the geometry so that others can understand exactly what, how big, and how far.
After you’ve made some drawings that talk, you’ll probably send the message around by printing — or as CAD users call it, plotting — them. AutoCAD 2005 introduces a redesigned, streamlined Plot dialog box, which makes the often-complex task of plotting a little less daunting. Chapter 12 in this section is your passport to navigating the revised plot process, understanding how the legacy of AutoCAD plotting influences current practice, and most of all getting a good-looking, properly scaled plot onto paper.
Chapter 9
Text with Character
• Using text styles to control text appearance
