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Circle in Sector
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| license: gpl-3.0 |
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| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <style> | |
| .sector, | |
| .circle { | |
| fill: none; | |
| stroke: #666; | |
| } | |
| .wedge { | |
| fill: #ddd; | |
| stroke: #333; | |
| stroke-width: 1.5px; | |
| } | |
| </style> | |
| <body> | |
| <script src="//d3js.org/d3.v3.min.js"></script> | |
| <script> | |
| var width = 960, | |
| height = 500, | |
| sectorRadius = 400; | |
| var arc = d3.svg.arc() | |
| .innerRadius(0); | |
| var svg = d3.select("body").append("svg") | |
| .attr("width", width) | |
| .attr("height", height) | |
| .append("g") | |
| .attr("transform", "translate(" + width / 2 + "," + (sectorRadius + (height - sectorRadius) / 2) + ")"); | |
| var sector = svg.append("path").attr("class", "sector"), | |
| wedge = svg.append("path").attr("class", "wedge"), | |
| circle = svg.append("circle").attr("class", "circle"); | |
| var ease = d3.ease("cubic-in-out"), | |
| duration = 7500; | |
| d3.timer(function(elapsed) { | |
| var t = ease(1 - Math.abs((elapsed % duration) / duration - .5) * 2), | |
| startAngle = -Math.PI / 3 * t - .1, | |
| endAngle = -startAngle, | |
| circleRadius = sectorRadius / (1 / Math.sin((endAngle - startAngle) / 2) + 1), | |
| p0 = [0, 0], | |
| p1 = [sectorRadius * Math.cos(startAngle - Math.PI / 2), sectorRadius * Math.sin(startAngle - Math.PI / 2)], | |
| p2 = [sectorRadius * Math.cos(endAngle - Math.PI / 2), sectorRadius * Math.sin(endAngle - Math.PI / 2)], | |
| t1 = cornerTangents(p0, p1, sectorRadius, circleRadius, 1), | |
| t2 = cornerTangents(p0, p2, sectorRadius, circleRadius, 1); | |
| sector.attr("d", arc | |
| .outerRadius(sectorRadius) | |
| .startAngle(startAngle) | |
| .endAngle(endAngle)); | |
| wedge.attr("d", "M" + p0 | |
| + "L" + t1[0] | |
| + "A" + circleRadius + "," + circleRadius + " 0 1,1 " + t2[0] | |
| + "Z"); | |
| circle | |
| .attr("cy", circleRadius - sectorRadius) | |
| .attr("r", circleRadius); | |
| }); | |
| function cornerTangents(p0, p1, r1, rc, cw) { | |
| var x01 = p0[0] - p1[0], | |
| y01 = p0[1] - p1[1], | |
| lo = (cw ? rc : -rc) / Math.sqrt(x01 * x01 + y01 * y01), | |
| ox = lo * y01, | |
| oy = -lo * x01, | |
| x1 = p0[0] + ox, | |
| y1 = p0[1] + oy, | |
| x2 = p1[0] + ox, | |
| y2 = p1[1] + oy, | |
| x3 = (x1 + x2) / 2, | |
| y3 = (y1 + y2) / 2, | |
| dx = x2 - x1, | |
| dy = y2 - y1, | |
| d2 = dx * dx + dy * dy, | |
| r = r1 - rc, | |
| D = x1 * y2 - x2 * y1, | |
| d = (dy < 0 ? -1 : 1) * Math.sqrt(r * r * d2 - D * D), | |
| cx0 = (D * dy - dx * d) / d2, | |
| cy0 = (-D * dx - dy * d) / d2, | |
| cx1 = (D * dy + dx * d) / d2, | |
| cy1 = (-D * dx + dy * d) / d2, | |
| dx0 = cx0 - x3, | |
| dy0 = cy0 - y3, | |
| dx1 = cx1 - x3, | |
| dy1 = cy1 - y3; | |
| // Pick the closer of the two intersection points. | |
| // TODO Is there a faster way to determine which intersection to use? | |
| if (dx0 * dx0 + dy0 * dy0 > dx1 * dx1 + dy1 * dy1) cx0 = cx1, cy0 = cy1; | |
| return [ | |
| [cx0 - ox, cy0 - oy], | |
| [cx0 * r1 / r, cy0 * r1 / r] | |
| ]; | |
| } | |
| </script> |
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