Controlling the Appearance of Your Model

Three-dimensional models are extremely useful in communicating your ideas to others, but sometimes you might find that the default appearance of your model is not exactly what you want. If you're only in a schematic design stage, you might want your model to look more like a sketch instead of a finished product. Conversely, if you're trying to sell someone on a concept, you might want a realistic look that includes materials and even special lighting. AutoCAD offers a variety of tools to help you get every type of view from a simple wireframe to a fully rendered image complete with chrome and wood. In the following sections, you'll get a preview of what is available to control the appearance of your model. Unfortunately, with the limited space of this book, I can cover these features only in general terms, but you'll at least gain an understanding of what is available, and if you're adventurous, you can experiment with the tools presented in this section.

Adding Materials

Having a 3D model of your design can be tremendously useful, but by adding materials, you communicate so much more to the person viewing your model. If you have a model that includes chrome and wood, for example, you can include those materials in your model to see firsthand how it will look, instead of having to imagine those materials.

AutoCAD has had the ability to assign materials to 3D models for some time, but AutoCAD 2008 makes it much easier to do. In this section, you'll try your hand at adding material to a box, and then you'll learn about some of the available options.

1. Open a new file by choosing File è New, and then in the Select Template dialog box, select the acad3D.dwt template.

2. Use the Box tool in the 3D Make control panel to draw a simple box like the one shown in Figure 6.8 earlier in this chapter.

3. Click Display Material Window in the Materials control panel (see the left image in Figure 6.40). The Materials palette appears, as shown on the right side of Figure 6.40.

Figure 6.40: The Display Material Window tool in the Materials control panel and the Materials palette

The Materials palette gives you full control over the materials that you assign to your object. You'll see a sample view of the current default material in the upper-left corner of the palette. You can add materials to this area or modify the current material. New objects are automatically assigned the default material.

Right now, the default material is rather basic. If you look carefully, you will see that the By Object option is turned on in the Material Editor panel of the Materials palette.

This means that the material uses the object's color, which is currently black or gray. Next, you will turn off this setting and make some modifications to the material's color:

1. Click the By Object option to turn it off. A color swatch appears to the left of the option.

2. Click the color swatch to open the Select Color dialog box (see Figure 6.41).

3. Click the green area in the Select Color dialog box, move the Luminance slider up to about the middle of the setting (see Figure 6.41), and then click OK. The box changes to the color you set.

Figure 6.41: The Select Color dialog box with a new color setting for the default material

In this exercise, you altered the default material's color and got immediate feedback from the box in the drawing area. The box changed to the selected color, showing you that the material is assigned to the box.

Color isn't the only thing you can add. Next, try turning your box into a brick box:

1. Click the Select Image button in the Diffuse Map group of the Materials palette. A file dialog box appears showing you a list of bitmap files.

   

2. If the bitmap files do not appear, browse to the Textures folder in the C:\Documents and Settings\All Users\ApplicationData\Autodesk\AutoCAD2008\R18.0\menu\ folder.

3. Scroll down to the middle of the list, locate the file named Masonry.Unit Masonry.Brick.Modular.Common.jpg, and then click Open. Your box changes in appearance, though it doesn't look quite right.

You've just added a brick bitmap to the default material. Notice that the brick takes over the material color. But the brick pattern might be larger than it should be in relation to the box.

Besides assigning a material, you also have control over the way a material is mapped to an object. The material map is the orientation and scale of a material on an object. Right now, in the example given in the previous exercises, the brick pattern is scaled in a way that is too large. In other situations, you might find the material map to be too small. The next exercise shows you how you can control the Material Map scale:

1. Click and hold the Planar Mapping tool in the Materials control panel to open the Mapping fly-out menu.

2. Drag down, and select the Box Mapping option.

3. At the Select faces or objects: prompt, click the box, and then press ↲. The box changes to display the brick pattern more clearly.

   

You might notice that grips have appeared on the box. These grips allow you to adjust the pattern. The brick pattern is a bit compressed on the box's side. You can make adjustments to the pattern by adjusting the grips:

1. At the Accept the mapping or [Move/Rotate/reseT/sWitch mapping mode]: prompt, drag the grip at the top of the box upward, as shown in Figure 6.42. As you move the grip, the pattern on the sides of the box scale upward.

2. Adjust the pattern to look more like Figure 6.42, and then release the grip.

3. Press ↲ to exit the Mapping tool.

Figure 6.42: Selecting the mapping grip and adjusting it to change the pattern on the side of the box

This exercise shows that you can adjust the way the pattern appears on the object.

You might have noticed the options in the prompt in step 1: Move/Rotate/reseT/ sWitch mapping mode. As you might guess, these options offer further editing capabilities. You can move or rotate the pattern using the Move or Rotate option. Rotate is useful for objects that have been rotated like the box earlier in this chapter. The Reset option resets the mapping to its default size and orientation. This is usually a size that just fits the object being mapped and is parallel to the WCS. The Switch option lets you switch to a different mapping style. You can use four mapping styles: Planar, Box, Spherical, and Cylindrical. Their names describe the way the map is applied to an object (see Figure 6.43).

Figure 6.43: Mapping styles

Adding Lights

Besides materials, lighting and shadows can really bring a 3D model to life. With AutoCAD lights, you can control the location and direction of illumination on your model.

AutoCAD offers several types of light, including sunlight. The sunlight option is significant because it allows you to do fairly accurate sun-shadow studies. You can enter a location and time of year, and AutoCAD will generate a light source. Other lights include the following:

• A point light behaves like a lightbulb shining in all directions from a single point. Illumination and shadows depend on an object's relationship to a point light.

• You can direct spotlights to point in a specific direction or at an object much like a theater spotlight or the headlights of a car. You can also control the spread and falloff of spotlights to produce a focused beam or a soft-edged spot.

• Distant lights are similar to spotlights but without controls for spread. Unlike point lights, distant lights illuminate objects and cast shadows from the same direction for all objects in your model.

Placing Lights in a Model

Each light has a slightly different method for placement and control in the model. To get a feel for how lights work, try adding a spotlight to the simple model. The following example describes how you might add a spotlight to the box from the materials exercise. You can try it on any model you have, or you can create a simple box for experimentation.

1. Click the downward-pointing arrows in the Light control panel title bar to expand the control panel. This gives you access to the tools that let you add lights to your model.

2. Click the Create A Spotlight tool.

3. You might see a warning message telling you that default lighting must be turned off. Click Yes.

   

   By default, AutoCAD places the light on the plane of the current UCS. You can then move it into a different Z coordinate by Shift+clicking and dragging the light's grip.

4. Click a location to the left of the object you want to illuminate. It doesn't really matter where you place the spotlight at first, since you can easily move it to another location using grips.

5. Click the location of the spotlight's target location, and then press ↲ to exit the command.

You have the light in place, but you might need to "raise" or "lower" the light source in the z-axis to illuminate part of the top, sides, or bottom of the box. Here's how you do it:

1. Click the light to expose its grips. You'll see not only its grips but also the light cone.

   

2. Hover over the light source grip to display the Grip tool, and then click the z-axis of the Grip tool.

   

3. Move the cursor upward so the light is above the object you are illuminating.

4. When you are satisfied with the light's location, click. You can also adjust the light target's z-axis location using the target grip's Grip tool. Although the model doesn't really change in appearance, you will see the results of your light when you render your view.

5. Click the Render button in the Render control panel. You will see exactly how the light affects your model in a render window, as shown in Figure 6.44.

   

Figure 6.44: A rendered view of a box

Once you've seen the rendered view, you can adjust the light's location. You can also use the light's grips to adjust the spotlight's hot spot and falloff to spread the light over a greater area or to narrow it down to a "tighter" beam (see Figure 6.45).

Figure 6.45: Samples of different falloff settings in the left side and the resulting rendered view on the right

The inner cone of light in the selected spotlight represents the hot spot. This is the main area that is illuminated by the spotlight. The falloff is the second outer cone displayed by the selected spotlight. The falloff cone indicates the outer edge of the spotlight that fades from full intensity to no illumination. To get a soft-edge effect on the spotlight, as shown in the upper-right view of Figure 6.45, widen the distance between the hot spot and falloff, as shown in the upper-left view. To get a sharper edge on the spotlight, shorten the distance between the hot spot and falloff, as shown in the bottom views of Figure 6.45.

If you need to adjust the light's intensity or other characteristics, you can double-click the light to open the Properties palette. There you control whether the light is on or off and its intensity, color, and even attenuation over a distance (see Figure 6.46).

Figure 6.46: The properties of a spotlight

Using Sunlight

The Sunlight tool operates in a different way from the other lights, so it needs some explanation. Unlike the way you use most of the other lights, you don't place the sunlight in the model. Instead, you tell AutoCAD where you are geographically and the time and the date. AutoCAD does the rest.

First, to turn on the sunlight, click the Viewport Lighting Mode button; then, click the Sun Status button. These two buttons appear in an orange color when they are in the "on" position.

To set your geographic location, click the Geographic Location button to open the Geographic Location dialog box.

To set the time of day, click the Edit The Sun button to open the Sun Properties palette, shown in Figure 6.47. There you'll find the date and time settings. To see the date and time settings, you might have to use the scroll bar to scroll the palette panels up. You can also control the color and intensity of the sunlight as well as the shadow settings.

Figure 6.47: The Sun Properties palette

Getting a Rendered View

In the "Adding Lights" section, you learned how to get a rendered view of your model after adding some lights. You click the Render button in the Render control panel. When you do this, a window appears, and a rendering of your model gradually appears.

You have numerous controls over the rendering output, but most of them are beyond the scope of this book. However, you'll need to know about a few essential items.

Saving Rendered Images

Once the rendering is completed, you can save the rendered view as a 2D image file by choosing File è Save from the Render window. You'll see a typical file dialog box that lets you select the location of the file. You can also select the file format, including TIF and JPEG, from the File Of Type drop-down list.

Controlling Resolution

If you want to set the image size in terms of pixels, you can do so before you render the model. The setting for the image size is in the expanded portion of the Render control panel. Click the downward-pointing arrows in the Render control panel title bar, and you'll see some additional controls (see Figure 6.48). Click the Output Size drop-down list to view the size options. The list displays several predefined sizes, or you can select Specify Output Size to set a custom size.

Figure 6.48: The expanded Render control panel shows the additional options.

Adding a Background

If you want to control the color of the background of the rendered image, you can do so through the View command. Choose View è Named Views. In the View Manager dialog box, click the New button to open the New View dialog box.

In the New View dialog box, enter a name for your view, and then select a background option from the drop-down list in the Background group.

The drop-down list in the left side of the Background group offers five options: Default, Solid, Gradient, Image, and Sun And Sky.

The Background dialog box appears if you select Solid, Gradient, or Image (see Figure 6.49). If you select Solid, you can click the Solid Options color box in the Background dialog box to open a Select Color dialog box that allows you to select a color. The Gradient option displays a top, middle, and bottom color sample box. Just as with the Solid Options color box, you can click the sample color boxes to open the Select Color dialog box.

Figure 6.49: The three modes of the Background dialog box

The Image option displays a Browse button so you can browse to an image file on your computer. The image you select appears in the sample box at the bottom. The Sun And Sky option lets you include a sky background with a sun. Select this option to open the Adjust Sun And Sky Background dialog box.

Once you've selected a background, click OK in the Background dialog box, and then click OK in the New View dialog box. Finally, in the View Manager dialog box, make sure you select your new view from the list box to the left, and click Set Current to make your new view the current one. This is an important step; otherwise, your background will not appear in the drawing. Click OK to exit the View Manager dialog box.

Getting a Wireframe or Shaded View

In the earlier tutorials of this chapter, you started to create 3D objects using the default visual style called Realistic. The name of this style might be a little misleading, because it doesn't actually give you a truly realistic view of your model. The Realistic visual style allows you to see curved surfaces more easily, but its main use is to show you material assignments of your object more easily. Sometimes it helps to use a different visual style, depending on your task. For example, a 3D wireframe view of your 3D model can help you visualize and select things that are behind a solid. AutoCAD includes several shaded view options that can bring out different features of your model.

1. Click the Visual Styles drop-down list in the Visual Styles control panel. Some graphic images appear that give you an idea of what each visual style shows you.

   

2. Select 3D Wireframe. You can also choose View è Visual Styles è Wireframe. Your model appears as a transparent wireframe object.

3. To return to the shaded view of your model, choose Realistic from the Visual Styles drop-down list, or choose View è Visual Styles è Realistic.

You might have noticed a few other Visual Styles options. Figure 6.50 shows those options as they are applied to a sphere. From left to right, they are 2D Wireframe, 3D Hidden, 3D Wireframe, Conceptual, and Realistic. 2D Wireframe and 3D Wireframe might appear the same, but 3D Wireframe uses a perspective view and a background color, while 2D Wireframe uses a parallel projection view and no background color.

Figure 6.50: Visual Styles applied to a sphere

Advanced users can control the features of these visual styles and can also create new visual styles. If you'd like to learn more, see Mastering AutoCAD 2008 and LT 2008.