Surfaces and Objects can also be made semi-transparent, which can make a significant improvement on almost any Shaded Model diagram.  Without it, ray trajectories inside volumes would be unseen by the viewer, objects completely or partially inside of other objects would be invisible, and objects behind other objects could not be seen at various plot rotations. 

WITHOUT OPACITY	WITH OPACITY

The opacity setting for each object or surface is right next to the Color setting in the Object or Surface Properties dialogs.  An opacity of 100% means the object/surface is completely opaque, or non-transparent.  An opacity of 0% is effectively the same as not drawing the object/surface altogether.



Sometimes, it takes trial and error to achieve the desired opacity levels for each surface and object to make your graphic look as you so desire. 

In addition to the surface specific settings, the Shaded Model and NSC Shaded Model have several settings which may be used to change the appearance of your diagram.  For the Shaded Model of sequential systems, there are settings for sectional drawing, Radial Segments, Angular Segments, Brightness, Background, and Opacity. 



For creating “smoother” surfaces, the radial and angular segments may be increased.  The Background will change the background color of the Shaded Model Layout, and can be set to a number of different colors, including the 24 different colors defined by the File > Preferences menu.

The brightness can be adjusted as well.  A higher percentage will increase the brightness of the display. 

In some cases, it is nice to be able to turn off the opacity settings without having to individually change the opacity for each individual surface via the Surface Properties dialog.  Thus, the “Opacity” setting can be set to Ignore.  Method 1 and Method 2 will use different algorithms to render the scene.  Some systems are difficult for OpenGL to render when there are a mixture of opaque and transparent surfaces and objects.  Simply choose whichever method yields the preferred rendering.

You may also choose to draw fractional segments of your elements via the “Draw Section” pull down menu in the settings of the Shaded Model.  Sections can be chosen in quarter increments, ¼, ½, ¾, or Full.