Cyrus–Beck algorithm

The Cyrus–Beck algorithm is a generalized line clipping algorithm. It was designed to be more efficient than the Sutherland–Cohen algorithm which uses repetitive clipping.^[1] Cyrus–Beck is a general algorithm and can be used with a convex polygon clipping window unlike Sutherland-Cohen that can be used only on a rectangular clipping area.

Here the parametric equation of a line in the view plane is:

${\begin{aligned}p(t)&=&tp_{1}+(1-t)p_{0}\\&=&p_{0}+t(p_{1}-p_{0})\end{aligned}}$

where $0\leq t\leq 1$ .

Now to find intersection point with the clipping window we calculate value of dot product. Let p_E be a point on the clipping plane E.

Calculate $n\cdot (p(t)-p_{E})$ .

if > 0 vector pointed towards interior

if = 0 vector pointed parallel to plane containing p

if < 0 vector pointed away from interior

Here n stands for normal of the current clipping plane (pointed away from interior).

By this we select the point of intersection of line and clipping window where (dot product = 0 ) and hence clip the line.

Notes

↑ "Clipping" (presentation)

References

Mike Cyrus, Jay Beck. "Generalized two- and three-dimensional clipping". Computers & Graphics, 1978: 23-28.
James D. Foley. Computer graphics: principles and practice. Addison-Wesley Professional, 1996. p. 117.

External links

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Cyrus–Beck algorithm

Notes

See also

References

External links