ol-ext
Version:
A set of cool extensions for OpenLayers (ol) in node modules structure
178 lines (152 loc) • 6.56 kB
JavaScript
import ol_geom_Geometry from 'ol/geom/Geometry.js'
import ol_geom_GeometryCollection from 'ol/geom/GeometryCollection.js'
import ol_geom_MultiLineString from 'ol/geom/MultiLineString.js'
import ol_geom_Polygon from 'ol/geom/Polygon.js'
import ol_geom_MultiPolygon from 'ol/geom/MultiPolygon.js'
import ol_geom_LineString from 'ol/geom/LineString.js'
import { ol_coordinate_dist2d } from '../geom/GeomUtils.js'
/** Create a cardinal spline version of this geometry.
* Original https://github.com/epistemex/cardinal-spline-js
* @see https://en.wikipedia.org/wiki/Cubic_Hermite_spline#Cardinal_spline
*
* @param {} options
* @param {Number} options.tension a [0,1] number / can be interpreted as the "length" of the tangent, default 0.5
* @param {Number} options.resolution size of segment to split
* @param {Integer} options.pointsPerSeg number of points per segment to add if no resolution is provided, default add 10 points per segment
*/
/** Cache cspline calculation on a geometry
* @param {} options
* @param {Number} options.tension a [0,1] number / can be interpreted as the "length" of the tangent, default 0.5
* @param {Number} options.resolution size of segment to split
* @param {Integer} options.pointsPerSeg number of points per segment to add if no resolution is provided, default add 10 points per segment
* @return {ol_geom_Geometry}
*/
ol_geom_Geometry.prototype.cspline = function(options){
// Calculate cspline
if (this.calcCSpline_){
if (this.csplineGeometryRevision != this.getRevision()
|| this.csplineOption != JSON.stringify(options)) {
this.csplineGeometry_ = this.calcCSpline_(options)
this.csplineGeometryRevision = this.getRevision();
this.csplineOption = JSON.stringify(options);
}
return this.csplineGeometry_;
} else {
// Default do nothing
return this;
}
};
ol_geom_GeometryCollection.prototype.calcCSpline_ = function(options) {
var g=[], g0=this.getGeometries();
for (var i=0; i<g0.length; i++) {
g.push(g0[i].cspline(options));
}
return new ol_geom_GeometryCollection(g);
};
ol_geom_MultiLineString.prototype.calcCSpline_ = function(options) {
var g=[], lines = this.getLineStrings();
for (var i=0; i<lines.length; i++) {
g.push(lines[i].cspline(options).getCoordinates());
}
return new ol_geom_MultiLineString(g);
};
ol_geom_Polygon.prototype.calcCSpline_ = function(options){
var g=[], g0=this.getCoordinates();
for (var i=0; i<g0.length; i++){
g.push((new ol_geom_LineString(g0[i])).cspline(options).getCoordinates());
}
return new ol_geom_Polygon(g);
};
ol_geom_MultiPolygon.prototype.calcCSpline_ = function(options) {
var g=[], g0=this.getPolygons();
for (var i=0; i<g0.length; i++) {
g.push(g0[i].cspline(options).getCoordinates());
}
return new ol_geom_MultiPolygon(g);
}
/** Calculate cspline on coordinates
* @param {Array<ol_geom_Geometry.coordinate>} line
* @param {} options
* @param {Number} options.tension a [0,1] number / can be interpreted as the "length" of the tangent, default 0.5
* @param {Number} options.resolution size of segment to split
* @param {Integer} options.pointsPerSeg number of points per segment to add if no resolution is provided, default add 10 points per segment
* @return {Array<ol_geom_Geometry.coordinate>}
*/
var ol_coordinate_cspline = function(line, options) {
if (!options) options={};
var tension = typeof options.tension === "number" ? options.tension : 0.5;
var length = 0;
var p0 = line[0];
line.forEach(function(p) {
length += ol_coordinate_dist2d(p0, p);
p0 = p;
})
var resolution = options.resolution || (length / line.length / (options.pointsPerSeg || 10));
var pts, res = [], // clone array
x, y, // our x,y coords
t1x, t2x, t1y, t2y, // tension vectors
c1, c2, c3, c4, // cardinal points
st, t, i; // steps based on num. of segments
// clone array so we don't change the original
//
pts = line.slice(0);
// The algorithm require a previous and next point to the actual point array.
// Check if we will draw closed or open curve.
// If closed, copy end points to beginning and first points to end
// If open, duplicate first points to beginning, end points to end
if (line.length>2 && line[0][0]==line[line.length-1][0] && line[0][1]==line[line.length-1][1]) {
pts.unshift(line[line.length-2]);
pts.push(line[1]);
} else {
pts.unshift(line[0]);
pts.push(line[line.length-1]);
}
// ok, lets start..
function dist2d(x1, y1, x2, y2) {
var dx = x2-x1;
var dy = y2-y1;
return Math.sqrt(dx*dx+dy*dy);
}
// 1. loop goes through point array
// 2. loop goes through each segment between the 2 pts + 1e point before and after
for (i=1; i < (pts.length - 2); i++) {
var d1 = dist2d (pts[i][0], pts[i][1], pts[i+1][0], pts[i+1][1]);
var numOfSegments = Math.round(d1/resolution);
var d=1;
if (options.normalize) {
d1 = dist2d (pts[i+1][0], pts[i+1][1], pts[i-1][0], pts[i-1][1]);
var d2 = dist2d (pts[i+2][0], pts[i+2][1], pts[i][0], pts[i][1]);
if (d1<d2) d = d1/d2;
else d = d2/d1;
}
// calc tension vectors
t1x = (pts[i+1][0] - pts[i-1][0]) * tension *d;
t2x = (pts[i+2][0] - pts[i][0]) * tension *d;
t1y = (pts[i+1][1] - pts[i-1][1]) * tension *d;
t2y = (pts[i+2][1] - pts[i][1]) * tension *d;
for (t=0; t <= numOfSegments; t++) {
// calc step
st = t / numOfSegments;
// calc cardinals
c1 = 2 * Math.pow(st, 3) - 3 * Math.pow(st, 2) + 1;
c2 = -(2 * Math.pow(st, 3)) + 3 * Math.pow(st, 2);
c3 = Math.pow(st, 3) - 2 * Math.pow(st, 2) + st;
c4 = Math.pow(st, 3) - Math.pow(st, 2);
// calc x and y cords with common control vectors
x = c1 * pts[i][0] + c2 * pts[i+1][0] + c3 * t1x + c4 * t2x;
y = c1 * pts[i][1] + c2 * pts[i+1][1] + c3 * t1y + c4 * t2y;
//store points in array
if (x && y) res.push([x,y]);
}
}
return res;
};
/** @private */
ol_geom_LineString.prototype.calcCSpline_ = function(options) {
var line = this.getCoordinates();
var res = ol_coordinate_cspline(line, options)
return new ol_geom_LineString(res);
}
// To use this module with ol/geom/Geometry
// import 'ol-ext/utils/cspline.js'
export default ol_coordinate_cspline