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Alpha Semi Transparency
OpenGL implements semi transparency with the alpha model. a ranges between 1—fully opaque—and 0—solid. a is the fourth component (in addition to R, G, and B) of each of the colors.
Alpha transparency examples.
Moritz uses the same alpha for the ambient, diffuse, and specular colors. Separate alpha values are specified for cells and materials; which one is used depends on whether cells are colored by cell or material. The same semi transparency is also used in ray traced pictures. Alpha transparency is also available for 3D CAD objects and solid bodies.
Alpha transparency must be enabled by the checking the Alpha Transparency box on the 3D Options property page for the OpenGL plot and on the Ray Trace Options property page for ray traced pictures. There are fields for specifying the alpha value on the cell, material, CAD objects, and solid body property pages and dialogs. The Cell and Material submenus of the context menus contain Alpha submenus containing explicit values and a link to appropriate property page.
In OpenGL, semi transparent objects are “blended” with existing objects to produce the illusion of transparency. Moritz draws semi transparent objects last. When more than one such object is present, the transparency depends on the drawing order (usually the order in which the objects are stored in the program) when two of them overlap. For complicated cells with internal surfaces, all of the surfaces are visible when the cell is semi transparent. The drawing order of cells in filling universes is only modified within the universe; a transparency may then not produce the expected result. Alpha transparency should be used in only a few simple and separated cells.
These limitations do not apply to the use of a transparency in ray tracing.
Examples of alpha transparency with reactors.
 White Rock Science http://www.whiterockscience.com/wrs.html 505 672 1105 |
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