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      <title>Fog</title>
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      <div class="title_topic4" id="xps10_pagetitle">Fog</div>
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      <p class="para_topic">Fog is the ability to display close objects in shades that are different than those of distant objects. To accomplish this change the intensity of pixels that comprise graphic primitives according to their Z, or depth value, resulting in a display that shows which geometry is closest to the viewer and which is furthest.</p>
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               <p class="para_td">Fog -Static Wireframe Rendering Style</p>
               <p align="center"><img align="bottom" src="graphics/prf_vis_specfx_fog_wire.gif"></p>
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               <p class="para_td">Fog - Shaded Rendering Style</p>
               <p align="center"><img align="bottom" src="graphics/prf_vis_specfx_fog_shade.gif"></p>
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      </table><br><p class="para_topic">Selecting the Fog toggle button turns Fog ON or OFF.</p>
      <p class="para_topic">Selecting the Fog Settings button does two things:</p>
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            <p class="para_item">It turns the Fog toggle ON, and opens the Fog dialog. Where you can specify the use of linear or non-linear fog.</p>
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            <p class="para_item">The color and density (or rate) of fog and the position of the front and back fog planes.</p>
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      <p class="para_topic">Fog option settings are applied to the work view, and are saved with the part file. When a new view is created, Fog is initialized to OFF.</p>
      <p class="para_topic">The Fog option menu at the top of the Fog dialog allows you to select the type of fog you want. You can select from one of the following three types of fog: Linear, Light or Heavy. Selecting Linear causes the dialog to make the Front and Back scales sensitive. Selecting Light or Heavy makes the Rate scale sensitive.</p>
      <div class="title_division">Linear Fog</div>
      <p class="para_division">Linear fog creates a fog effect by changing the color intensity of portions of objects in a fixed linear progression according to their distance from the viewer. Portions of the image farther from the viewer are drawn with more of the fog color, while portions of the image closer to the viewer are drawn with more of the geometry color.</p>
      <p class="para_division">When you select Linear fog, the Front and Back scales at the bottom of the dialog become sensitive to let you adjust the fog planes. You can also use the Color controls to adjust fog color.</p>
      <div class="title_division">Front and Back</div>
      <p class="para_division">When using the Linear fog option, the Front and Back scales are functional. The Front scale defines the beginning of fog. The Back scale defines the point at which fog reaches its maximum. Anything at or beyond the Back Z plane is at the maximum fog level.</p>
      <p class="para_division">Moving the Front and Back planes close together causes an increase in the fog effect. (The closer the Front and Back fog planes, the less Z-distance you will have to go from no fog to maximum fog.)</p>
      <p class="para_division">Note that the Front defaults to the front Z plane of the view volume, and the Back defaults to the back Z plane of the view volume. The view volume encompasses more than the max/min of the displayed geometry, and consequently moving the Front or Backsliders may have no effect until it reaches the geometry.</p>
      <div class="title_division">Fog Color</div>
      <p class="para_division">You can use the Color area of the Fog dialog to specify the background color for fog, or you can mix your own fog color.</p>
      <p class="para_division">To use the background color, click the Use Background Color toggle.</p>
      <p class="para_division">To create your own fog color, click the desired color method button, RGB, HSV or HLS, and mix the desired color using the three control scales. The fog color is updated in the graphics window when you click Apply.</p>
      <div class="title_division">Light and Heavy Fog</div>
      <p class="para_division">The Light and Heavy fog options denote Non-linear fog. Light fog produces a fog effect less pervasive than Heavy fog. You could still, for example, see some objects in the distance with Light fog that you could not see with Heavy fog.</p>
      <p class="para_division">When you select Light or Heavy fog, the Rate scale at the bottom of the dialog becomes sensitive to let you specify the rate at which an object fades as the distance in the view increases. Dragging the scale toward the Near end of the scale causes there to be less fog density (i.e., less fog). Dragging the scale towards the Far end of the scale causes there to be greater fog density. The default position for the Rate scale is midway between Near and Far.</p>
      <p class="para_division">With Light and Heavy fog you can use the Color controls to adjust fog color. </p>
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