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Point-in-polygon
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| <!doctype html> | |
| <meta charset="utf-8"> | |
| <html> | |
| <head> | |
| <style type="text/css"> | |
| #canvas { | |
| width: 800px; | |
| height: 400px; | |
| border: 1px solid #666; | |
| } | |
| path { | |
| fill: none; | |
| stroke-width: 1px; | |
| stroke: #666; | |
| } | |
| circle { | |
| fill: steelblue; | |
| } | |
| circle.selected { | |
| fill: #ff0000; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <div id="canvas"></div> | |
| <span id="clear">[clear]</span> | |
| <script src="http://d3js.org/d3.v3.min.js"></script> | |
| <script type="text/javascript" src="main.js"></script> | |
| </body> | |
| </html> |
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| ;(function() { | |
| var copy, | |
| coords = [], | |
| width = 800, | |
| height = 400, | |
| margin = 50, | |
| line = d3.svg.line(), | |
| dragStart = function() { | |
| coords = []; | |
| g.selectAll("path").remove(); | |
| }, | |
| drawPath = function(terminator) { | |
| g.append("path").attr({ | |
| d: line(coords) | |
| }); | |
| if (terminator) { | |
| g.select("#terminator").remove(); | |
| g.append("path").attr({ | |
| id: "terminator", | |
| d: line([coords[0], coords[coords.length-1]]) | |
| }); | |
| } | |
| }, | |
| dragMove = function() { | |
| dot.classed("selected", false); | |
| coords.push(d3.mouse(this)); | |
| dot.each(function(d, i) { | |
| point = [d3.select(this).attr("cx"), d3.select(this).attr("cy")]; | |
| if (pointInPolygon(point, coords)) { | |
| d3.select(this).classed("selected", true) | |
| } | |
| }); | |
| drawPath(); | |
| }, | |
| dragEnd = function() { | |
| drawPath(true); | |
| } | |
| drag = d3.behavior.drag() | |
| .on("dragstart", dragStart) | |
| .on("drag", dragMove) | |
| .on("dragend", dragEnd), | |
| // from https://github.com/substack/point-in-polygon | |
| pointInPolygon = function (point, vs) { | |
| // ray-casting algorithm based on | |
| // http://www.ecse.rpi.edu/Homepages/wrf/Research/Short_Notes/pnpoly.html | |
| var xi, xj, i, intersect, | |
| x = point[0], | |
| y = point[1], | |
| inside = false; | |
| for (var i = 0, j = vs.length - 1; i < vs.length; j = i++) { | |
| xi = vs[i][0], | |
| yi = vs[i][1], | |
| xj = vs[j][0], | |
| yj = vs[j][1], | |
| intersect = ((yi > y) != (yj > y)) | |
| && (x < (xj - xi) * (y - yi) / (yj - yi) + xi); | |
| if (intersect) inside = !inside; | |
| } | |
| return inside; | |
| }, | |
| svg = d3.select("#canvas").append("svg").attr({ | |
| width: width, | |
| height: height | |
| }).call(drag), | |
| g = svg.append("g"), | |
| randPoint = function(min, max) { | |
| return Math.floor(Math.random() * (max-min)) + min; | |
| }, | |
| points = function(numPoints) { | |
| var data = []; | |
| for (i=0; i < numPoints; i++) { | |
| data.push({x: randPoint(margin, width-margin), y: randPoint(margin, height-margin)}); | |
| } | |
| return data; | |
| }, | |
| dot = g.selectAll("circle") | |
| .data(points(1000)) | |
| .enter().append("circle") | |
| .attr({ | |
| cx: function(d, i) { | |
| return d.x; | |
| }, | |
| cy: function(d, i) { | |
| return d.y; | |
| }, | |
| r: 3 | |
| }); | |
| d3.select("#clear").on("click", function() { | |
| dot.classed("selected", false); | |
| dragStart(); | |
| }) | |
| }()); |
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