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import Queue from 'tinyqueue'
import pointInPolygon from 'point-in-polygon'
import { orient2d as orient } from 'robust-predicates'
/**
* Since vite uses native ESM, it doesnt support the syntax of "concaveman" library becuase it still uses commonjs, so we need to convert it to ESM.
* Copied direct from:
* @see {@link https://github.com/mapbox/concaveman}
*/
export default function concaveman(points, concavity, lengthThreshold) {
// a relative measure of concavity; higher value means simpler hull
concavity = Math.max(0, concavity === undefined ? 2 : concavity)
// when a segment goes below this length threshold, it won't be drilled down further
lengthThreshold = lengthThreshold || 0
// start with a convex hull of the points
var hull = fastConvexHull(points)
// index the points with an R-tree
var tree = new RBush(16)
tree.toBBox = function(a) {
return {
minX: a[0],
minY: a[1],
maxX: a[0],
maxY: a[1]
}
}
tree.compareMinX = function(a, b) {
return a[0] - b[0]
}
tree.compareMinY = function(a, b) {
return a[1] - b[1]
}
tree.load(points)
// turn the convex hull into a linked list and populate the initial edge queue with the nodes
var queue = []
for (var i = 0, last; i < hull.length; i++) {
var p = hull[i]
tree.remove(p)
last = insertNode(p, last)
queue.push(last)
}
// index the segments with an R-tree (for intersection checks)
var segTree = new RBush(16)
for (i = 0; i < queue.length; i++) segTree.insert(updateBBox(queue[i]))
var sqConcavity = concavity * concavity
var sqLenThreshold = lengthThreshold * lengthThreshold
// process edges one by one
while (queue.length) {
var node = queue.shift()
var a = node.p
var b = node.next.p
// skip the edge if it's already short enough
var sqLen = getSqDist(a, b)
if (sqLen < sqLenThreshold) continue
var maxSqLen = sqLen / sqConcavity
// find the best connection point for the current edge to flex inward to
p = findCandidate(
tree,
node.prev.p,
a,
b,
node.next.next.p,
maxSqLen,
segTree
)
// if we found a connection and it satisfies our concavity measure
if (p && Math.min(getSqDist(p, a), getSqDist(p, b)) <= maxSqLen) {
// connect the edge endpoints through this point and add 2 new edges to the queue
queue.push(node)
queue.push(insertNode(p, node))
// update point and segment indexes
tree.remove(p)
segTree.remove(node)
segTree.insert(updateBBox(node))
segTree.insert(updateBBox(node.next))
}
}
// convert the resulting hull linked list to an array of points
node = last
var concave = []
do {
concave.push(node.p)
node = node.next
} while (node !== last)
concave.push(node.p)
return concave
}
function findCandidate(tree, a, b, c, d, maxDist, segTree) {
var queue = new Queue([], compareDist)
var node = tree.data
// search through the point R-tree with a depth-first search using a priority queue
// in the order of distance to the edge (b, c)
while (node) {
for (var i = 0; i < node.children.length; i++) {
var child = node.children[i]
var dist = node.leaf ? sqSegDist(child, b, c) : sqSegBoxDist(b, c, child)
if (dist > maxDist) continue // skip the node if it's farther than we ever need
queue.push({
node: child,
dist: dist
})
}
while (queue.length && !queue.peek().node.children) {
var item = queue.pop()
var p = item.node
// skip all points that are as close to adjacent edges (a,b) and (c,d),
// and points that would introduce self-intersections when connected
var d0 = sqSegDist(p, a, b)
var d1 = sqSegDist(p, c, d)
if (
item.dist < d0 &&
item.dist < d1 &&
noIntersections(b, p, segTree) &&
noIntersections(c, p, segTree)
)
return p
}
node = queue.pop()
if (node) node = node.node
}
return null
}
function compareDist(a, b) {
return a.dist - b.dist
}
// square distance from a segment bounding box to the given one
function sqSegBoxDist(a, b, bbox) {
if (inside(a, bbox) || inside(b, bbox)) return 0
var d1 = sqSegSegDist(
a[0],
a[1],
b[0],
b[1],
bbox.minX,
bbox.minY,
bbox.maxX,
bbox.minY
)
if (d1 === 0) return 0
var d2 = sqSegSegDist(
a[0],
a[1],
b[0],
b[1],
bbox.minX,
bbox.minY,
bbox.minX,
bbox.maxY
)
if (d2 === 0) return 0
var d3 = sqSegSegDist(
a[0],
a[1],
b[0],
b[1],
bbox.maxX,
bbox.minY,
bbox.maxX,
bbox.maxY
)
if (d3 === 0) return 0
var d4 = sqSegSegDist(
a[0],
a[1],
b[0],
b[1],
bbox.minX,
bbox.maxY,
bbox.maxX,
bbox.maxY
)
if (d4 === 0) return 0
return Math.min(d1, d2, d3, d4)
}
function inside(a, bbox) {
return (
a[0] >= bbox.minX &&
a[0] <= bbox.maxX &&
a[1] >= bbox.minY &&
a[1] <= bbox.maxY
)
}
// check if the edge (a,b) doesn't intersect any other edges
function noIntersections(a, b, segTree) {
var minX = Math.min(a[0], b[0])
var minY = Math.min(a[1], b[1])
var maxX = Math.max(a[0], b[0])
var maxY = Math.max(a[1], b[1])
var edges = segTree.search({
minX: minX,
minY: minY,
maxX: maxX,
maxY: maxY
})
for (var i = 0; i < edges.length; i++) {
if (intersects(edges[i].p, edges[i].next.p, a, b)) return false
}
return true
}
function cross(p1, p2, p3) {
return orient(p1[0], p1[1], p2[0], p2[1], p3[0], p3[1])
}
// check if the edges (p1,q1) and (p2,q2) intersect
function intersects(p1, q1, p2, q2) {
return (
p1 !== q2 &&
q1 !== p2 &&
cross(p1, q1, p2) > 0 !== cross(p1, q1, q2) > 0 &&
cross(p2, q2, p1) > 0 !== cross(p2, q2, q1) > 0
)
}
// update the bounding box of a node's edge
function updateBBox(node) {
var p1 = node.p
var p2 = node.next.p
node.minX = Math.min(p1[0], p2[0])
node.minY = Math.min(p1[1], p2[1])
node.maxX = Math.max(p1[0], p2[0])
node.maxY = Math.max(p1[1], p2[1])
return node
}
// speed up convex hull by filtering out points inside quadrilateral formed by 4 extreme points
function fastConvexHull(points) {
var left = points[0]
var top = points[0]
var right = points[0]
var bottom = points[0]
// find the leftmost, rightmost, topmost and bottommost points
for (var i = 0; i < points.length; i++) {
var p = points[i]
if (p[0] < left[0]) left = p
if (p[0] > right[0]) right = p
if (p[1] < top[1]) top = p
if (p[1] > bottom[1]) bottom = p
}
// filter out points that are inside the resulting quadrilateral
var cull = [left, top, right, bottom]
var filtered = cull.slice()
for (i = 0; i < points.length; i++) {
if (!pointInPolygon(points[i], cull)) filtered.push(points[i])
}
// get convex hull around the filtered points
return convexHull(filtered)
}
// create a new node in a doubly linked list
function insertNode(p, prev) {
var node = {
p: p,
prev: null,
next: null,
minX: 0,
minY: 0,
maxX: 0,
maxY: 0
}
if (!prev) {
node.prev = node
node.next = node
} else {
node.next = prev.next
node.prev = prev
prev.next.prev = node
prev.next = node
}
return node
}
// square distance between 2 points
function getSqDist(p1, p2) {
var dx = p1[0] - p2[0],
dy = p1[1] - p2[1]
return dx * dx + dy * dy
}
// square distance from a point to a segment
function sqSegDist(p, p1, p2) {
var x = p1[0],
y = p1[1],
dx = p2[0] - x,
dy = p2[1] - y
if (dx !== 0 || dy !== 0) {
var t = ((p[0] - x) * dx + (p[1] - y) * dy) / (dx * dx + dy * dy)
if (t > 1) {
x = p2[0]
y = p2[1]
} else if (t > 0) {
x += dx * t
y += dy * t
}
}
dx = p[0] - x
dy = p[1] - y
return dx * dx + dy * dy
}
// segment to segment distance, ported from http://geomalgorithms.com/a07-_distance.html by Dan Sunday
function sqSegSegDist(x0, y0, x1, y1, x2, y2, x3, y3) {
var ux = x1 - x0
var uy = y1 - y0
var vx = x3 - x2
var vy = y3 - y2
var wx = x0 - x2
var wy = y0 - y2
var a = ux * ux + uy * uy
var b = ux * vx + uy * vy
var c = vx * vx + vy * vy
var d = ux * wx + uy * wy
var e = vx * wx + vy * wy
var D = a * c - b * b
var sc, sN, tc, tN
var sD = D
var tD = D
if (D === 0) {
sN = 0
sD = 1
tN = e
tD = c
} else {
sN = b * e - c * d
tN = a * e - b * d
if (sN < 0) {
sN = 0
tN = e
tD = c
} else if (sN > sD) {
sN = sD
tN = e + b
tD = c
}
}
if (tN < 0.0) {
tN = 0.0
if (-d < 0.0) sN = 0.0
else if (-d > a) sN = sD
else {
sN = -d
sD = a
}
} else if (tN > tD) {
tN = tD
if (-d + b < 0.0) sN = 0
else if (-d + b > a) sN = sD
else {
sN = -d + b
sD = a
}
}
sc = sN === 0 ? 0 : sN / sD
tc = tN === 0 ? 0 : tN / tD
var cx = (1 - sc) * x0 + sc * x1
var cy = (1 - sc) * y0 + sc * y1
var cx2 = (1 - tc) * x2 + tc * x3
var cy2 = (1 - tc) * y2 + tc * y3
var dx = cx2 - cx
var dy = cy2 - cy
return dx * dx + dy * dy
}
function compareByX(a, b) {
return a[0] === b[0] ? a[1] - b[1] : a[0] - b[0]
}
function convexHull(points) {
points.sort(compareByX)
var lower = []
for (var i = 0; i < points.length; i++) {
while (
lower.length >= 2 &&
cross(lower[lower.length - 2], lower[lower.length - 1], points[i]) <= 0
) {
lower.pop()
}
lower.push(points[i])
}
var upper = []
for (var ii = points.length - 1; ii >= 0; ii--) {
while (
upper.length >= 2 &&
cross(upper[upper.length - 2], upper[upper.length - 1], points[ii]) <= 0
) {
upper.pop()
}
upper.push(points[ii])
}
upper.pop()
lower.pop()
return lower.concat(upper)
}
export { concaveman }
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