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@w8r
Created Aug 2, 2017
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Liang-Barsky line clipping
/**
* Liang-Barsky function by Daniel White
*
* @link http://www.skytopia.com/project/articles/compsci/clipping.html
*
* @param {number} x0
* @param {number} y0
* @param {number} x1
* @param {number} y1
* @param {array<number>} bbox
* @return {array<array<number>>|null}
*/
function liangBarsky (x0, y0, x1, y1, bbox) {
var [xmin, xmax, ymin, ymax] = bbox;
var t0 = 0, t1 = 1;
var dx = x1 - x0, dy = y1 - y0;
var p, q, r;
for(var edge = 0; edge < 4; edge++) { // Traverse through left, right, bottom, top edges.
if (edge === 0) { p = -dx; q = -(xmin - x0); }
if (edge === 1) { p = dx; q = (xmax - x0); }
if (edge === 2) { p = -dy; q = -(ymin - y0); }
if (edge === 3) { p = dy; q = (ymax - y0); }
r = q / p;
if (p === 0 && q < 0) return null; // Don't draw line at all. (parallel line outside)
if(p < 0) {
if (r > t1) return null; // Don't draw line at all.
else if (r > t0) t0 = r; // Line is clipped!
} else if (p > 0) {
if(r < t0) return null; // Don't draw line at all.
else if (r < t1) t1 = r; // Line is clipped!
}
}
return [
[x0 + t0 * dx, y0 + t0 * dy],
[x0 + t1 * dx, y0 + t1 * dy]
];
}
@ashleedawg

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@ashleedawg ashleedawg commented Jul 27, 2021

worked like a charm, thanks!

@w8r

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@w8r w8r commented Jul 27, 2021

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