Opacity is the degree to which a graphical object obscures objects which are rendered behind it.
Graphical objects which have a level of opacity less than 100% can be "seen through". The objects which are rendered behind are blended with the object in front; the resulting effect being like looking through a pane of coloured glass.
Opacity appears as an attribute in many graphical contexts, including [3D rendering], and Web Styling.
Opacity is the opposite of transparency.
See also:
- "Opacity (optics)" article on Wikipedia
- http://nehe.gamedev.net/tutorial/blending/16001/
