add lisp packages

This commit is contained in:
2020-12-05 21:29:49 +01:00
parent 85e20365ae
commit a6e2395755
7272 changed files with 1363243 additions and 0 deletions

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export default function(polygon) {
var i = -1,
n = polygon.length,
a,
b = polygon[n - 1],
area = 0;
while (++i < n) {
a = b;
b = polygon[i];
area += a[1] * b[0] - a[0] * b[1];
}
return area / 2;
}

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export default function(polygon) {
var i = -1,
n = polygon.length,
x = 0,
y = 0,
a,
b = polygon[n - 1],
c,
k = 0;
while (++i < n) {
a = b;
b = polygon[i];
k += c = a[0] * b[1] - b[0] * a[1];
x += (a[0] + b[0]) * c;
y += (a[1] + b[1]) * c;
}
return k *= 3, [x / k, y / k];
}

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export default function(polygon, point) {
var n = polygon.length,
p = polygon[n - 1],
x = point[0], y = point[1],
x0 = p[0], y0 = p[1],
x1, y1,
inside = false;
for (var i = 0; i < n; ++i) {
p = polygon[i], x1 = p[0], y1 = p[1];
if (((y1 > y) !== (y0 > y)) && (x < (x0 - x1) * (y - y1) / (y0 - y1) + x1)) inside = !inside;
x0 = x1, y0 = y1;
}
return inside;
}

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// Returns the 2D cross product of AB and AC vectors, i.e., the z-component of
// the 3D cross product in a quadrant I Cartesian coordinate system (+x is
// right, +y is up). Returns a positive value if ABC is counter-clockwise,
// negative if clockwise, and zero if the points are collinear.
export default function(a, b, c) {
return (b[0] - a[0]) * (c[1] - a[1]) - (b[1] - a[1]) * (c[0] - a[0]);
}

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import cross from "./cross.js";
function lexicographicOrder(a, b) {
return a[0] - b[0] || a[1] - b[1];
}
// Computes the upper convex hull per the monotone chain algorithm.
// Assumes points.length >= 3, is sorted by x, unique in y.
// Returns an array of indices into points in left-to-right order.
function computeUpperHullIndexes(points) {
var n = points.length,
indexes = [0, 1],
size = 2;
for (var i = 2; i < n; ++i) {
while (size > 1 && cross(points[indexes[size - 2]], points[indexes[size - 1]], points[i]) <= 0) --size;
indexes[size++] = i;
}
return indexes.slice(0, size); // remove popped points
}
export default function(points) {
if ((n = points.length) < 3) return null;
var i,
n,
sortedPoints = new Array(n),
flippedPoints = new Array(n);
for (i = 0; i < n; ++i) sortedPoints[i] = [+points[i][0], +points[i][1], i];
sortedPoints.sort(lexicographicOrder);
for (i = 0; i < n; ++i) flippedPoints[i] = [sortedPoints[i][0], -sortedPoints[i][1]];
var upperIndexes = computeUpperHullIndexes(sortedPoints),
lowerIndexes = computeUpperHullIndexes(flippedPoints);
// Construct the hull polygon, removing possible duplicate endpoints.
var skipLeft = lowerIndexes[0] === upperIndexes[0],
skipRight = lowerIndexes[lowerIndexes.length - 1] === upperIndexes[upperIndexes.length - 1],
hull = [];
// Add upper hull in right-to-l order.
// Then add lower hull in left-to-right order.
for (i = upperIndexes.length - 1; i >= 0; --i) hull.push(points[sortedPoints[upperIndexes[i]][2]]);
for (i = +skipLeft; i < lowerIndexes.length - skipRight; ++i) hull.push(points[sortedPoints[lowerIndexes[i]][2]]);
return hull;
}

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export {default as polygonArea} from "./area.js";
export {default as polygonCentroid} from "./centroid.js";
export {default as polygonHull} from "./hull.js";
export {default as polygonContains} from "./contains.js";
export {default as polygonLength} from "./length.js";

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export default function(polygon) {
var i = -1,
n = polygon.length,
b = polygon[n - 1],
xa,
ya,
xb = b[0],
yb = b[1],
perimeter = 0;
while (++i < n) {
xa = xb;
ya = yb;
b = polygon[i];
xb = b[0];
yb = b[1];
xa -= xb;
ya -= yb;
perimeter += Math.sqrt(xa * xa + ya * ya);
}
return perimeter;
}