Extrusion is the process of creating three-dimensional geometry out of flat, two-dimensional shapes by drawing the 2-D shape along a path in 3-D space. The extrusion path may be a straight line or any kind of curve. If the path is linear, it may be normal to, or at any other angle to the extruded shape.
Extrusion may be used to both build a 3-D object to begin with, or to add additional geometry to an existing 3-D polygon mesh object. In the latter case, a polygon (or group of polygons) comprising part of the surface of the object are extruded. This extrusion can be either outward or inward on the 3-D object, creating positive or negative surface detail. Extrusion of polygons on 3-D objects is often associated with a beveling type of effect.
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Created: May 5, 1997
Revised: May 5, 1997