Last active
February 9, 2016 02:12
Closest Point to Segment
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| license: gpl-3.0 |
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| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <style> | |
| .circle { | |
| fill: none; | |
| stroke: red; | |
| stroke-width: 2px; | |
| } | |
| .circle.intersects { | |
| stroke: green; | |
| } | |
| .line { | |
| stroke: #000; | |
| stroke-dasharray: 3,3; | |
| } | |
| .segment { | |
| stroke: #000; | |
| stroke-width: 1.5px; | |
| } | |
| text { | |
| text-anchor: middle; | |
| } | |
| </style> | |
| <body> | |
| <script src="//d3js.org/d3.v3.min.js"></script> | |
| <script> | |
| var width = 960, | |
| height = 500; | |
| var svg = d3.select("body").append("svg") | |
| .attr("width", width) | |
| .attr("height", height) | |
| .on("mousemove", function() { move(d3.mouse(this)); }); | |
| var p0 = [width * .2, height * .8], | |
| p1 = [width * .8, height * .2]; | |
| svg.append("path") | |
| .attr("class", "line") | |
| .attr("d", "M" + [0, height] + "L" + [width, 0]); | |
| svg.append("path") | |
| .attr("class", "segment") | |
| .attr("d", "M" + p0 + "L" + p1); | |
| svg.selectAll(".endpoint") | |
| .data([p0, p1]) | |
| .enter().append("circle") | |
| .attr("class", "endpoint") | |
| .attr("transform", function(d) { return "translate(" + d + ")"; }) | |
| .attr("r", 4.5); | |
| svg.selectAll(".tick") | |
| .data(d3.range(.1, 1, .1)) | |
| .enter().append("circle") | |
| .attr("class", "tick") | |
| .attr("transform", function(d) { return "translate(" + d3.interpolate(p0, p1)(d) + ")"; }) | |
| .attr("r", 2.5); | |
| var projection = svg.append("path") | |
| .attr("class", "line"); | |
| var closest = svg.append("circle") | |
| .attr("class", "circle intersects") | |
| .attr("r", 4.5); | |
| var label = svg.append("text") | |
| .attr("y", -6); | |
| move([Math.random() * width, Math.random() * height]); | |
| function move(p2) { | |
| var t = pointLineSegmentParameter(p2, p0, p1), | |
| x10 = p1[0] - p0[0], | |
| y10 = p1[1] - p0[1], | |
| p3 = [p0[0] + t * x10, p0[1] + t * y10]; | |
| label.attr("transform", "translate(" + p3 + ")rotate(" + Math.atan2(y10, x10) / Math.PI * 180 + ")").text(t.toFixed(3)); | |
| closest.attr("transform", "translate(" + p3 + ")").classed("intersects", Math.abs(t - .5) < .5); | |
| projection.attr("d", "M" + p2 + "L" + p3); | |
| } | |
| function pointLineSegmentParameter(p2, p0, p1) { | |
| var x10 = p1[0] - p0[0], y10 = p1[1] - p0[1], | |
| x20 = p2[0] - p0[0], y20 = p2[1] - p0[1]; | |
| return (x20 * x10 + y20 * y10) / (x10 * x10 + y10 * y10); | |
| } | |
| </script> |
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