Use Geometric.js to rotate and translate a polygon.
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February 3, 2019 17:05
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Polygon Rotation and Translation
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| license: gpl-3.0 |
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta charset="utf8" /> | |
| <style> | |
| body { | |
| margin: 0; | |
| } | |
| circle { | |
| stroke: #fff; | |
| } | |
| polygon { | |
| fill: steelblue; | |
| } | |
| text { | |
| font-family: "Helvetica Neue", sans-serif; | |
| font-size: 20px; | |
| pointer-events: none; | |
| text-anchor: middle; | |
| } | |
| text.text-drag { | |
| fill: white; | |
| } | |
| text.hide { | |
| opacity: 0; | |
| transition: opacity .3s; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <script src="https://d3js.org/d3.v5.min.js"></script> | |
| <script src="https://unpkg.com/geometric@1.0.9/build/geometric.min.js"></script> | |
| <script> | |
| var width = window.innerWidth, | |
| height = window.innerHeight, | |
| center = [width / 2, height / 2], | |
| points = [ | |
| [center[0] - 100, center[1] - 100], | |
| [center[0] + 100, center[1] - 100], | |
| [center[0] + 100, center[1] + 100], | |
| [center[0] - 100, center[1] + 100] | |
| ], | |
| dragStartPoint = [0, 0]; | |
| var polygonDrag = d3.drag() | |
| .on("start", _ => { | |
| dragStartPoint = [event.clientX, event.clientY]; | |
| }) | |
| .on("drag", _ => { | |
| var dragPoint = [event.clientX, event.clientY]; | |
| points = geometric.polygonTranslate( | |
| points, | |
| geometric.lineAngle([dragStartPoint, dragPoint]), | |
| geometric.lineLength([dragStartPoint, dragPoint]) | |
| ); | |
| dragStartPoint = dragPoint; | |
| update(); | |
| }); | |
| var handleDrag = d3.drag() | |
| .on("start", d => { | |
| dragStartPoint = d; | |
| }) | |
| .on("drag", d => { | |
| var centroid = geometric.polygonCentroid(points); | |
| var dragPoint = [event.clientX, event.clientY]; | |
| points = geometric.polygonRotate( | |
| points, | |
| geometric.lineAngle([dragPoint, centroid]) - geometric.lineAngle([dragStartPoint, centroid]), | |
| centroid | |
| ); | |
| dragStartPoint = dragPoint; | |
| update(); | |
| }); | |
| var svg = d3.select("body").append("svg").attr("width", width).attr("height", height); | |
| var polygon = svg.append("polygon").call(polygonDrag); | |
| var dragLabel = svg.append("text") | |
| .attr("class", "text-drag") | |
| .attr("transform", "translate(" + center + ")") | |
| .text("Drag"); | |
| var rotateLabel = svg.selectAll(".text-rotate") | |
| .data(points) | |
| .enter().append("text") | |
| .attr("class", "text-rotate") | |
| .attr("transform", (d, i) => "translate(" + d + ") rotate(" + (i === 0 ? -45 : i === 1 ? 45 : i === 2 ? 135 : -135) + ")") | |
| .attr("dy", -20) | |
| .text("← Rotate →"); | |
| var updateCount = 0; | |
| update(); | |
| function update(){ | |
| updateCount++; | |
| if (updateCount === 2){ | |
| d3.selectAll("text").classed("hide", 1); | |
| } | |
| polygon.attr("points", points); | |
| var handles = svg.selectAll("circle") | |
| .data(points) | |
| handles.enter().append("circle") | |
| .attr("r", 10) | |
| .merge(handles) | |
| .attr("transform", d => "translate(" + d + ")") | |
| .call(handleDrag); | |
| } | |
| </script> | |
| </body> | |
| </html> |
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