import "centroid"; // TODO Unify this code with d3.geom.polygon centroid? // TODO Enforce positive area for exterior, negative area for interior? var d3_geo_pathCentroid = { point: d3_geo_pathCentroidPoint, // For lines, weight by length. lineStart: d3_geo_pathCentroidLineStart, lineEnd: d3_geo_pathCentroidLineEnd, // For polygons, weight by area. polygonStart: function() { d3_geo_pathCentroid.lineStart = d3_geo_pathCentroidRingStart; }, polygonEnd: function() { d3_geo_pathCentroid.point = d3_geo_pathCentroidPoint; d3_geo_pathCentroid.lineStart = d3_geo_pathCentroidLineStart; d3_geo_pathCentroid.lineEnd = d3_geo_pathCentroidLineEnd; } }; function d3_geo_pathCentroidPoint(x, y) { d3_geo_centroidX0 += x; d3_geo_centroidY0 += y; ++d3_geo_centroidZ0; } function d3_geo_pathCentroidLineStart() { var x0, y0; d3_geo_pathCentroid.point = function(x, y) { d3_geo_pathCentroid.point = nextPoint; d3_geo_pathCentroidPoint(x0 = x, y0 = y); }; function nextPoint(x, y) { var dx = x - x0, dy = y - y0, z = Math.sqrt(dx * dx + dy * dy); d3_geo_centroidX1 += z * (x0 + x) / 2; d3_geo_centroidY1 += z * (y0 + y) / 2; d3_geo_centroidZ1 += z; d3_geo_pathCentroidPoint(x0 = x, y0 = y); } } function d3_geo_pathCentroidLineEnd() { d3_geo_pathCentroid.point = d3_geo_pathCentroidPoint; } function d3_geo_pathCentroidRingStart() { var x00, y00, x0, y0; // For the first point, … d3_geo_pathCentroid.point = function(x, y) { d3_geo_pathCentroid.point = nextPoint; d3_geo_pathCentroidPoint(x00 = x0 = x, y00 = y0 = y); }; // For subsequent points, … function nextPoint(x, y) { var dx = x - x0, dy = y - y0, z = Math.sqrt(dx * dx + dy * dy); d3_geo_centroidX1 += z * (x0 + x) / 2; d3_geo_centroidY1 += z * (y0 + y) / 2; d3_geo_centroidZ1 += z; z = y0 * x - x0 * y; d3_geo_centroidX2 += z * (x0 + x); d3_geo_centroidY2 += z * (y0 + y); d3_geo_centroidZ2 += z * 3; d3_geo_pathCentroidPoint(x0 = x, y0 = y); } // For the last point, return to the start. d3_geo_pathCentroid.lineEnd = function() { nextPoint(x00, y00); }; }