2 types of line clipping algorithm with example. Cohen-Sutherland Line Clipping and Liang-Barsky Line Clipping Algorithm By Shilpa. Liang-Barsky line clipping algorithm. ▫ Sutherland-Hogeman polygon clipping. 3. Pedher Johansson. Department of Computing Science, Umeå University. Liang – Barsky line clipping algorithm is faster line clipper algorithm based on analysis of the parametric equation of a line segment. Parametric equation of line .
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The Liang-Barsky line clipping algorithm in a nutshell!
In reality of course, this would only apply if the line was fully inside the lighter blue area. What we’ll do is go through each edge border in turn Left, Right, Bottom, Topand at each stage we will either tweak t0 or t1, or we may find out that the line is outside the border completely, and therefore doesn’t need drawing – in which case we will cut the algorithm there and then!
Otherwise, skip to next edge. Apply this algorithm to the dlipping with coordinates 30, 60 and 60, 25 against the window.
To add a little context for those reading, the Liang-Barsky algorithm determines the segment of an infinite straight line that intersects an axis-aligned rectangle, if any. Since we don’t have LaTeX markup in this exchange, I’ll use bold to represent n-dimensional vectors.
Parametric equation of line segment: And yes, it can be trivially extended to clipping lines against n-dimensional axis-aligned hyperrectangles pretty trivially. Engineering in your pocket Download our mobile app and study on-the-go. At Skytopia, we pride ourselves in making some of the most difficult concepts as easy to understand as possible. Do the same for the other edges! Using these equations Cyrus and Beck developed an algorithm that is generated more efficient than the Cohen Sutherland algorithm.
White onwards other than the code which you can freely use. So the beginning of the line P 0 will be represented by 0and the end of the line P 1 by 1. The Liang-Barsky line clipping algorithm in a nutshell!
We can store these values in variables, as we will need to adjust them as the algorithm progresses. Therefore we ignore it. Now you’ve practically understood the whole algorithm because we can generalize what we’ve done for the left edge, to the other edges! If P is more than zero however which it isn’t in this example btw – we’ve already had the above executed, so algoritthm below basky is only for future edge checks! In the Liang-Barsky algoritmh we first the point clipping condition in parametric form: We hope you agree that the colour coding, examples, numerous diagrams pixel-precise and to scale!
We need to find out some values before we proceed. More values need calculating for our first check: If the line is parallel to the X axis, for example then p1 loang p2 must be zero.
But bear with me, since the following algorithm will gradually clip it down, edge by edge. Diagram 1b Just for reference, remember that: You get question papers, syllabus, subject analysis, answers – all in one app.
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Liang-Barsky Line Clipping Algorithm – Game Development Stack Exchange
Maybe try out Computer Graphics Stack Exchange computergraphics. Sign up or log in Sign agorithm using Liaang. Sign up using Facebook. Explain Liang Barsky line clipping algorithm. Diagram 1b Left edge check: If there is a segment of line inside the clip region, a sequence of infinite line intersections must go entering, entering, exiting, and exiting as shown in figure Now go to next edge.
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