Liang–Barsky algorithm: Difference between revisions

Revision as of 13:58, 10 April 2025

Latest revision as of 07:26, 10 August 2025

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{{Short description|Line-clipping algorithm}}

In [[computer graphics]], the '''Liang–Barsky algorithm''' (named after [[You-Dong Liang]] and [[Brian A. Barsky]]) is a [[line clipping]] algorithm. The Liang–Barsky algorithm uses the [[parametric equation]] of a line and inequalities describing the range of the clipping window to determine the intersections between the line and the [[clip window]]. With these intersections, it knows which portion of the line should be drawn. So this algorithm is significantly more efficient than [[Cohen–Sutherland]]. The idea of the Liang–Barsky clipping algorithm is to do as much testing as possible before computing line intersections.

The algorithm uses the parametric form of a straight line:

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To compute the final [[line segment]]:

# A line parallel to a clipping window edge has <math>p_i = 0</math> for that boundary.

# If for that <math>i</math>, <math>q_i < 0</math>, then the line is completely outside and can be eliminated.