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// MIT Licensed.
/**
* Fast, destructive implementation of Liang-Barsky line clipping algorithm.
* It clips a 2D segment by a rectangle.
* @author Alexander Milevski <info@w8r.name>
* @license MIT
*/
const EPSILON = 1e-6;
const INSIDE = 1;
const OUTSIDE = 0;
function clipT(num, denom, c) {
const [tE, tL] = c;
if (Math.abs(denom) < EPSILON) return num < 0;
const t = num / denom;
if (denom > 0) {
Iif (t > tL) return 0;
if (t > tE) c[0] = t;
} else {
Iif (t < tE) return 0;
Eif (t < tL) c[1] = t;
}
return 1;
}
/**
* @param {Point} a
* @param {Point} b
* @param {BoundingBox} box [xmin, ymin, xmax, ymax]
* @param {Point?} [da]
* @param {Point?} [db]
* @return {number}
*/
export default function clip(a, b, box, da?, db?) {
const [x1, y1] = a;
const [x2, y2] = b;
const dx = x2 - x1;
const dy = y2 - y1;
Eif (da === undefined || db === undefined) {
da = a;
db = b;
} else {
da[0] = a[0];
da[1] = a[1];
db[0] = b[0];
db[1] = b[1];
}
Iif (
Math.abs(dx) < EPSILON &&
Math.abs(dy) < EPSILON &&
x1 >= box[0] &&
x1 <= box[2] &&
y1 >= box[1] &&
y1 <= box[3]
) {
return INSIDE;
}
const c = [0, 1];
Eif (
clipT(box[0] - x1, dx, c) &&
clipT(x1 - box[2], -dx, c) &&
clipT(box[1] - y1, dy, c) &&
clipT(y1 - box[3], -dy, c)
) {
const [tE, tL] = c;
Eif (tL < 1) {
db[0] = x1 + tL * dx;
db[1] = y1 + tL * dy;
}
if (tE > 0) {
da[0] += tE * dx;
da[1] += tE * dy;
}
return INSIDE;
}
return OUTSIDE;
}
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