92 lines
3.0 KiB
JavaScript
92 lines
3.0 KiB
JavaScript
goog.provide('ol.geom.flat.interiorpoint');
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goog.require('ol');
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goog.require('ol.array');
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goog.require('ol.geom.flat.contains');
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/**
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* Calculates a point that is likely to lie in the interior of the linear rings.
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* Inspired by JTS's com.vividsolutions.jts.geom.Geometry#getInteriorPoint.
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* @param {Array.<number>} flatCoordinates Flat coordinates.
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* @param {number} offset Offset.
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* @param {Array.<number>} ends Ends.
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* @param {number} stride Stride.
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* @param {Array.<number>} flatCenters Flat centers.
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* @param {number} flatCentersOffset Flat center offset.
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* @param {Array.<number>=} opt_dest Destination.
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* @return {Array.<number>} Destination.
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*/
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ol.geom.flat.interiorpoint.linearRings = function(flatCoordinates, offset,
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ends, stride, flatCenters, flatCentersOffset, opt_dest) {
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var i, ii, x, x1, x2, y1, y2;
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var y = flatCenters[flatCentersOffset + 1];
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/** @type {Array.<number>} */
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var intersections = [];
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// Calculate intersections with the horizontal line
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var end = ends[0];
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x1 = flatCoordinates[end - stride];
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y1 = flatCoordinates[end - stride + 1];
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for (i = offset; i < end; i += stride) {
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x2 = flatCoordinates[i];
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y2 = flatCoordinates[i + 1];
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if ((y <= y1 && y2 <= y) || (y1 <= y && y <= y2)) {
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x = (y - y1) / (y2 - y1) * (x2 - x1) + x1;
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intersections.push(x);
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}
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x1 = x2;
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y1 = y2;
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}
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// Find the longest segment of the horizontal line that has its center point
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// inside the linear ring.
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var pointX = NaN;
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var maxSegmentLength = -Infinity;
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intersections.sort(ol.array.numberSafeCompareFunction);
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x1 = intersections[0];
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for (i = 1, ii = intersections.length; i < ii; ++i) {
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x2 = intersections[i];
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var segmentLength = Math.abs(x2 - x1);
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if (segmentLength > maxSegmentLength) {
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x = (x1 + x2) / 2;
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if (ol.geom.flat.contains.linearRingsContainsXY(
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flatCoordinates, offset, ends, stride, x, y)) {
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pointX = x;
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maxSegmentLength = segmentLength;
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}
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}
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x1 = x2;
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}
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if (isNaN(pointX)) {
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// There is no horizontal line that has its center point inside the linear
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// ring. Use the center of the the linear ring's extent.
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pointX = flatCenters[flatCentersOffset];
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}
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if (opt_dest) {
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opt_dest.push(pointX, y);
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return opt_dest;
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} else {
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return [pointX, y];
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}
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};
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/**
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* @param {Array.<number>} flatCoordinates Flat coordinates.
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* @param {number} offset Offset.
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* @param {Array.<Array.<number>>} endss Endss.
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* @param {number} stride Stride.
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* @param {Array.<number>} flatCenters Flat centers.
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* @return {Array.<number>} Interior points.
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*/
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ol.geom.flat.interiorpoint.linearRingss = function(flatCoordinates, offset, endss, stride, flatCenters) {
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var interiorPoints = [];
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var i, ii;
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for (i = 0, ii = endss.length; i < ii; ++i) {
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var ends = endss[i];
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interiorPoints = ol.geom.flat.interiorpoint.linearRings(flatCoordinates,
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offset, ends, stride, flatCenters, 2 * i, interiorPoints);
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offset = ends[ends.length - 1];
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}
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return interiorPoints;
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};
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