### Lighting Tab

The Lighting tab of the CAD and Graphic Setup dialog box (Edit | Setup | Cad and Graphic Setup) lets you define lighting settings to use with your part in the Graphics Display window.

CAD and Graphic Setup dialog box-Lighting tab

The Lighting tab consists of three areas that allow you to define your light sources, your light model, and transparencies.

Light Source:

The Light source area defines up to four light sources, each specifying their respective light’s direction and colors. You can create a new light source by selecting the appropriate number and clicking the Enabled check box.

With the exception of the first light source, which remains always enabled, the Enabled check box lets you turn the current light source on or off.

Light Direction:

Once you enable a light source, an active light direction button becomes selected with a red outline. These buttons define the direction from which the light originates.

The center light direction button acts as if the light comes from the direction you are located as if shining through your computer screen onto the CAD part. The other direction buttons define light coming from other angles.

Light Colors:

You can change the Ambient, Diffuse, or Specular light for the current light source by simply clicking on the colored rectangle beneath each type of light and selecting the new color from the Color dialog box that appears.

Note: Be aware that light source 1 has white as the default color for Diffuse and Specular, while the other three light sources use black as the default color.

Ambient illumination is light that has been scattered so much by the environment that its direction is impossible to determine - it seems to come from all directions. Backlight in a room has a large ambient component, since most of the light that reaches your eye has bounced off many surfaces. A spotlight outdoors has a tiny ambient component; most of the light travels is the same direction, and since you are outdoors, very little of the light reaches your eye after bouncing off other objects. When ambient light strikes a surface, it’s scattered equally in all directions.

Diffuse light comes from one direction, so it's brighter if it comes squarely down on a surface than if it barely glances off the surface. Once it hits a surface, however, it’s scattered equally in all directions, so it appears equally bright, no matter where the eye is located. Any light coming from a particular position or direction probably has a diffuse component.

Specular light comes from a particular direction, and it tends to bounce off the surface in a preferred direction. A laser beam bouncing off a mirror produces almost 100 percent specular reflection. Shiny metal or plastic has a high specular component and chalk or carpet has almost none. You can think of specular light as "shininess".

If you disable a light source, the Light direction and Light colors buttons become unavailable for selection.

Light Model:

The Light Model area defines information applied to the entire scene, regardless of the light source.

Two sided lighting – This check box determines whether or not the front and back faces of surfaces should be lighted. You should select this check box for imported IGES files and for some other CAD formats when the surface normals are not correct.

Back face culling – This check box determines whether or not Planner should cull, or hide, the back faces of surfaces. You should select this check box for IGES files, and some other Cad formats, when the surface normals are not correct.

Ambient – This box defines the ambient color applied to the entire scene. Click on the box to change colors.

Transparency:

Sometimes parts of a CAD model interfere with seeing other areas of the model. Enabling transparency reduces this problem by allowing you to "look through" the part image. In this way you can see sections of the part that may actually be hidden.

Once you have enabled transparency you can then select features and other items on your part by clicking on your part model through the transparent model.

Once you select the Enable transparency check box, you can select the other items in the Transparency area.

Read-only depth buffer - This check box changes how the lighting and color interact by making the depth buffer read-only. This will cause the graphics image to change, perhaps only in a small unnoticeable way, but perhaps in a more noticeable way. It is up to you to determine whether or not the results produce a better looking image. Consult an external resource on OpenGL for additional information on the depth buffer.

Back face culling - This check box causes Planner to not draw the back faces of surfaces for the selected transparent object.

% Trans - This slider lets you determine the percentage of transparency for the selected object. Moving the slider to the left makes the display object more opaque, while moving the slider to the right makes it more transparent.

Once you define transparencies here you can easily switch them on and off using the Toggle Graphic View Transparency icon from the Graphic View toolbar. See the "Graphic View Toolbar" topic for more information.