Line drawing algorithm
From Wikipedia, the free encyclopedia
A line drawing algorithm is a graphical algorithm for approximating a line segment on discrete graphical media. On discrete media, such as pixel-based displays and printers, line drawing requires such an approximation (in nontrivial cases).
On continuous media, by contrast, no algorithm is necessary to draw a line. For example, oscilloscopes use natural phenomena to draw lines and curves.
[edit] A naïve line-drawing algorithm
dx = x2 - x1
dy = y2 - y1
for x from x1 to x2 {
y = y1 + (dy) * (x - x1)/(dx)
plot(x, y)
}
It is assumed here that the points have already been ordered so that x2 > x1. This algorithm works just fine when dx > = dy, but it is quite slow on a digital computer, as it requires floating-point calculations. If dx < dy, the line becomes quite sparse, and in the limiting case of dx = 0, only a single point is plotted!
[edit] List of line drawing algorithms
The following is a partial list of line drawing algorithms:
- Bresenham's line algorithm — optimized to use only additions (i.e. no divisions or multiplications); it also avoids floating-point computations.
- Xiaolin Wu's line algorithm — can perform anti-aliasing
