Lines and Curves
Lines and curves are used to draw graphics output on raster devices. As discussed in this overview, a line is a set of highlighted pixels on a raster display (or a set of dots on a printed page) identified by two points: a starting point and an ending point. A regular curve is a set of highlighted pixels on a raster display (or dots on a printed page) that defines the perimeter (or part of the perimeter) of a conic section. An irregular curve is a set of pixels that defines a curve that does not fit the perimeter of a conic section.