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As you work with your 3D model, you will want to get an idea of how it looks with hidden lines removed. Frequently, object intersections and shapes are not readily apparent until you can see what object Iines in front of others

AutoCAD provides two helpful viewing commands for this situation. First, the Hide command allows you to quickly view your with the hidden lines removed.You can then assess where surfaces are and get a better feel for the model. Hide is also an option at plot time, allowing you to create printed line drawings of a 3D model. You can then render the hard copy using manual techniques if you want.

The second command, Shademode, lets you work with your 3D model as if it is composed Qfopaque surfaces instead of lines. Shademode also has a variety of options for controlling how colors are applied. You can’t plot views as they appear when Shademode is turned on. It is intended only as a visualization aid for constructing  3D models.

Let’s begin by looking at the Hide command ~d then discuss the Shademode command ..

Removing Hidden Lines

Hide is perhaps the easiest of all the 3D viewing commands to use. Try the following to see a hidden-line view of your model.

  1. Restore the view you saved earlier with the name 3D using the View dialog box. This shows you that you can store and recall 3D views as, well as 2D views.
  2. Choose View > Hide, or enter Hi at the command prompt. AutoCAD displays this message:
    Regenerating drawing
    If the drawing is a complex one, a graphic bar appears in the status bar showing the progress of the hidden-line removal. When AutoCAD is done, the image appears with the hidden lines removed (see Figure 15.14).
  3. After you’ve reviewed the results of the View > Hide, choose View > Regen or type Re to return to your Wireframe view.
    FIGURE 15.14

    FIGURE 15.14


This hidden-line view remains until your drawing is regenerated. Note that you cannot use the View command to save a hidden-line view. You can, however, save this view as a Slide.

Although it did not take much time to perform a hidden-line removal on this drawing, the more complex the 3D drawing, the longer the Hide command takes. But even the most complex model you create does not take much more than several minutes.

Using a Shaded Mode with Your 3D Model

If you’re used to working with Wireframe 3D images, the Hide command is usually good enough to give you an idea of how your model looks from time to time as you work on it. But when you want to get an even better visualization of the form your model is taking on, it’s time for the Shademode command. To see how Shademode works, try the following exercise.

  1. First, open the Shade by right-clicking any toolbar, then selecting Shade from the popup menu. The Shade toolbar appears.
  2. Click the Flat Shaded tool on the Shade toolbar. You can also select View > Shade > Flat Shaded. Notice that a ground plane appears. This is an aid to help you better visualize the model and it isn’t actually part of your drawing.
  3. Click the GRID button in the status bar. Notice that the 3D grid turns off. Click the GRID button again to turn it back on. The grid you see with the shaded view does not reflect the grid spacing you set in the Drafting Settings dialog box. It’s only there to help you visualize the plane represented by the x-y axes at 0 elevation. It also shows you the limits of your drawing, just like the standard grid. .
  4. Click the Flat Shaded, Edges On tool from the Shade toolbar, or choose View > Shade > Flat Shaded, Edges On from the menu bar. Notice that this time, the edge of the surfaces is highlighted to help you see the surfaces (see Figure 15.15).
  5. Now click the Hidden tool or choose View > Shade > Hidden. Your.drawing changes to look similarly to the way it looked when you used the View >Hide option. But there is a difference in this option.
  6. Choose View > Regen. The view doesn’t change. AutoCAO remains,in a Shaded view mode until you click 20 Wireframe on the Shade toolbar or View Shade > 20 Wireframe.
  7. Click the 20 Wireframe tool in the Shade toolbar. Your drawing returns to the Wireframe view you started with. Remember this tool when you want to return to the standard 20 Wireframe view of your drawing.
FIGURE 15.15

FIGURE 15.15

The Hidden Shade mode allows you to better visualize your 30 drawing. Depending on the type of model and its complexity, you can even work on it with the Hidden Shade mode turned on. You can always go back to the Wireframe view using the 20 Wireframe option  Infact, there may be times when you will want to see through” a wall or other object while you’re editing your 30 model. That’s when the 20 Wireframe view will be more helpful.

Before you continue editing the Unit plan, you may want to know the functions of the other options on the Shade toolbar, The 30 Wireframe option displays a view similar to the 20 Wrreframe view, with the addition of the ground plane you first saw in step 2. The other two options, Gouraud Shade and Gouraud Shade, Edges On are both used to get a smooth shade effect on curved surfaces as shown in Figure 15.16. These Gouraud options don’t have an effect on flat surface models like the Unit plan.



The Edges On options display the edge of flat surfaces. The spheres in Figure 15.16 are made up of flat surfaces, which can be seen in the Hidden example. The Gouraud Shade options smooth out the facets of the sphere. The Gouraud Shade, Edge On option shows the edges of the facets even though the smoothing effect is on.

There is a third method for visualizing your model that allows you to place varying light sources in your drawing. The AutoCAD rendering functions on the Render toolbar let you adjust light reflectance of surfaces, smooth out faceted surfaces such as spheres and cylinders, and place light sources accurately. You’ll get a chance to work with the rendering functions in Chapter 17. For now, let’s look at some other factors that affect how a 3D model will look when it is shaded or when hidden lines are removed.

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