Wiggling along the Pacific Coast Highway. Inspired by lots of driving up and down this road. Thanks to clhenrick and veltman for thinking through the linestring ordering with me. Data from Natural Earth. Point along path interpolation from Mike Bostock.
<!doctype html>
<meta charset="utf-8">
<style>
.westcoast {
stroke: none;
fill: #b8b8b8;
}
.pch {
fill: none;
stroke: red;
stroke-width: 2px;
}
.ball {
fill: #000;
}
.interior-boundary {
fill: none;
stroke: #fff;
stroke-opacity: 0.8;
stroke-dasharray: 8,6;
}
</style>
<body>
<script src="//d3js.org/d3.v4.js"></script>
<script src="//d3js.org/topojson.v1.min.js"></script>
<script>
var width = 500;
var height = 900;
var projection = d3.geoAlbers()
.scale(2400)
.translate([850,550])
var path = d3.geoPath()
.projection(projection)
var svg = d3.select("body").append("svg")
.attr("width", width)
.attr("height", height)
.append("g")
.attr("transform", "rotate(-13)");
d3.json("westcoast_pch.json", function(data) {
/* map */
svg.append("path")
.datum(topojson.feature(data, data.objects.westcoast))
.attr("d", path)
.attr("class", "westcoast")
/* interior boundaries between states */
svg.append("path")
.datum(topojson.mesh(data, data.objects.westcoast, function(a, b) {
return a !== b;
}))
.attr("d", path)
.attr("class", "interior-boundary");
/* road */
var pch = svg.append("path")
.datum(topojson.feature(data, data.objects.pch))
.attr("d", path)
.attr("class", "pch")
/* wiggle */
var circle = svg.append("circle")
.attr("r", 3)
.attr("class", "ball")
.attr("transform", "translate(0,0)")
circle
.transition()
.duration(20000)
.attrTween("transform", translateAlong(pch.node()));
/* https://bl.ocks.org/mbostock/1705868 */
// Returns an attrTween for translating along the specified path element.
function translateAlong(path) {
var l = path.getTotalLength();
return function(d, i, a) {
return function(t) {
var p = path.getPointAtLength(t * l);
return "translate(" + p.x + "," + p.y + ")";
};
};
}
});
</script>