node-red-contrib-tak-registration
Version:
A Node-RED node to register to TAK and to help wrap files as datapackages to send to TAK
112 lines (111 loc) • 3.68 kB
JavaScript
;
// Cohen-Sutherland line clipping algorithm, adapted to efficiently
// handle polylines rather than just segments
Object.defineProperty(exports, "__esModule", { value: true });
function lineclip(points, bbox, result) {
var len = points.length, codeA = bitCode(points[0], bbox), part = [], i, codeB, lastCode;
var a;
var b;
if (!result)
result = [];
for (i = 1; i < len; i++) {
a = points[i - 1];
b = points[i];
codeB = lastCode = bitCode(b, bbox);
while (true) {
if (!(codeA | codeB)) {
// accept
part.push(a);
if (codeB !== lastCode) {
// segment went outside
part.push(b);
if (i < len - 1) {
// start a new line
result.push(part);
part = [];
}
}
else if (i === len - 1) {
part.push(b);
}
break;
}
else if (codeA & codeB) {
// trivial reject
break;
}
else if (codeA) {
// a outside, intersect with clip edge
a = intersect(a, b, codeA, bbox);
codeA = bitCode(a, bbox);
}
else {
// b outside
b = intersect(a, b, codeB, bbox);
codeB = bitCode(b, bbox);
}
}
codeA = lastCode;
}
if (part.length)
result.push(part);
return result;
}
exports.lineclip = lineclip;
// Sutherland-Hodgeman polygon clipping algorithm
function polygonclip(points, bbox) {
var result, edge, prev, prevInside, i, p, inside;
// clip against each side of the clip rectangle
for (edge = 1; edge <= 8; edge *= 2) {
result = [];
prev = points[points.length - 1];
prevInside = !(bitCode(prev, bbox) & edge);
for (i = 0; i < points.length; i++) {
p = points[i];
inside = !(bitCode(p, bbox) & edge);
// if segment goes through the clip window, add an intersection
if (inside !== prevInside)
result.push(intersect(prev, p, edge, bbox));
if (inside)
result.push(p); // add a point if it's inside
prev = p;
prevInside = inside;
}
points = result;
if (!points.length)
break;
}
return result;
}
exports.polygonclip = polygonclip;
// intersect a segment against one of the 4 lines that make up the bbox
function intersect(a, b, edge, bbox) {
return edge & 8
? [a[0] + ((b[0] - a[0]) * (bbox[3] - a[1])) / (b[1] - a[1]), bbox[3]] // top
: edge & 4
? [a[0] + ((b[0] - a[0]) * (bbox[1] - a[1])) / (b[1] - a[1]), bbox[1]] // bottom
: edge & 2
? [bbox[2], a[1] + ((b[1] - a[1]) * (bbox[2] - a[0])) / (b[0] - a[0])] // right
: edge & 1
? [bbox[0], a[1] + ((b[1] - a[1]) * (bbox[0] - a[0])) / (b[0] - a[0])] // left
: null;
}
// bit code reflects the point position relative to the bbox:
// left mid right
// top 1001 1000 1010
// mid 0001 0000 0010
// bottom 0101 0100 0110
function bitCode(p, bbox) {
var code = 0;
if (p[0] < bbox[0])
code |= 1;
// left
else if (p[0] > bbox[2])
code |= 2; // right
if (p[1] < bbox[1])
code |= 4;
// bottom
else if (p[1] > bbox[3])
code |= 8; // top
return code;
}