An example of d3-contour.
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March 6, 2019 05:25
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Contour Plot III
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| license: gpl-3.0 | |
| redirect: https://observablehq.com/@d3/animated-contours |
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| <!DOCTYPE html> | |
| <canvas width="960" height="500"></canvas> | |
| <script src="https://d3js.org/d3-array.v1.min.js"></script> | |
| <script src="https://d3js.org/d3-color.v1.min.js"></script> | |
| <script src="https://d3js.org/d3-contour.v1.min.js"></script> | |
| <script src="https://d3js.org/d3-geo.v1.min.js"></script> | |
| <script src="https://d3js.org/d3-interpolate.v1.min.js"></script> | |
| <script src="https://d3js.org/d3-scale.v1.min.js"></script> | |
| <script src="https://d3js.org/d3-scale-chromatic.v1.min.js"></script> | |
| <script src="https://d3js.org/d3-timer.v1.min.js"></script> | |
| <script> | |
| // Populate a grid of (n+2)×(m+2) values where -9.6 ≤ x ≤ 9.6 and -5 ≤ y ≤ 5. | |
| var n = 240, m = 125, values = new Array((n + 2) * (m + 2)); | |
| for (var j = -0.5, k = 0; j < m + 1; ++j) { | |
| for (var i = -0.5; i < n + 1; ++i, ++k) { | |
| values[k] = value(i / n * 19.2 - 9.6, 5 - j / m * 10); | |
| } | |
| } | |
| var canvas = document.querySelector("canvas"), | |
| context = canvas.getContext("2d"), | |
| color = d3.scaleSequential(d3.interpolateRdBu).domain([-1, 1]), | |
| path = d3.geoPath(null, context), | |
| thresholds = d3.range(-1.2, 1, 0.2), | |
| contours = d3.contours().size([n + 2, m + 2]); | |
| context.scale(canvas.width / (n + 1), canvas.width / (n + 1)); | |
| context.translate(-0.5, -0.5); | |
| d3.timer(function(t) { | |
| var dv = (t % 1000) / 1000 * 0.2; | |
| contours | |
| .thresholds(thresholds.map(function(v) { return v + dv; })) | |
| (values) | |
| .forEach(fill); | |
| }); | |
| function fill(geometry) { | |
| context.beginPath(); | |
| path(geometry); | |
| context.fillStyle = color(geometry.value); | |
| context.fill(); | |
| } | |
| function value(x, y) { | |
| return Math.sin(x + y) * Math.sin(x - y); | |
| } | |
| </script> |
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