KoGor/README.md

## README.md

      
    Raw
  

              README.md
            
          
    Marker animation along SVG "path" element with D3.js: animating "path" and marker movement synchronously, marker rotate according to tangent line to path.

  
## index.html
<!DOCTYPE html>
<html lang="en">
<meta charset="utf-8">
<head>
  <title>SVG path animation</title>
  <link href="style.css" rel="stylesheet">
  <script src="http://d3js.org/d3.v3.min.js"></script>
  <script src="http://d3js.org/queue.v1.min.js"></script>
</head>
<body>
  <!-- start -->
  <div id="pathAnimation">
    <script src="pathAdvancedFollow.js"></script>
    <form>
      <input type="checkbox" id="pathTrigger" name="visibility" value="hidden">Show/Hide path</br>
    </form>
  </div>
  <!-- end -->
</body>
</html>

## pathAdvancedFollow.js
queue()
.defer(d3.xml, "wiggle.svg", "image/svg+xml")
.await(ready);

function ready(error, xml) {

  //Adding our svg file to HTML document
  var importedNode = document.importNode(xml.documentElement, true);
  d3.select("#pathAnimation").node().appendChild(importedNode);

  var svg = d3.select("svg");

  var path = svg.select("path#wiggle"),
  startPoint = pathStartPoint(path);

  var checkbox = d3.selectAll("input[name=visibility]");

  checkbox.on("change", function() {
    if (this.checked) {
      path.style("visibility", "visible");
      this.value = "visible";
    } else {
      path.style("visibility", "hidden");
      this.value = "hidden";
    };
  });

  var marker = svg.append("image")
  .attr("xlink:href", "rocket.png")
  .attr("transform", "translate(" + startPoint[0] + "," + startPoint[1] + ")")
  .attr("width", 48)
  .attr("height", 24);

  transition();

  //Get path start point for placing marker
  function pathStartPoint(path) {
    var d = path.attr("d"),
    dsplitted = d.split(" ");
    return dsplitted[1].split(",");
  };

  function transition() {
    marker.transition()
        .duration(17000)
        .attrTween("transform", translateAlong(path.node()))
        .each("end", transition);// infinite loop
  };

  function translateAlong(path) {
    var l = path.getTotalLength();
    var t0 = 0;
    return function(i) {
      return function(t) {
        var p0 = path.getPointAtLength(t0 * l);//previous point
        var p = path.getPointAtLength(t * l);////current point
        var angle = Math.atan2(p.y - p0.y, p.x - p0.x) * 180 / Math.PI;//angle for tangent
        t0 = t;
        //Shifting center to center of rocket
        var centerX = p.x - 24,
        centerY = p.y - 12;
        return "translate(" + centerX + "," + centerY + ")rotate(" + angle + " 24" + " 12" +")";
      }
    }
  }
}

## rocket.png

      
    Raw
  

              rocket.png
            
          
## style.css
path {
  visibility: hidden;
  fill: none;
  stroke: #000;
  stroke-width: 1px;
}

## wiggle.svg

      
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              wiggle.svg
            
          
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	<!DOCTYPE html>
	<html lang="en">
	<meta charset="utf-8">
	<head>
	<title>SVG path animation</title>
	<link href="style.css" rel="stylesheet">
	<script src="http://d3js.org/d3.v3.min.js"></script>
	<script src="http://d3js.org/queue.v1.min.js"></script>
	</head>
	<body>
	<!-- start -->
	<div id="pathAnimation">
	<script src="pathAdvancedFollow.js"></script>
	<form>
	<input type="checkbox" id="pathTrigger" name="visibility" value="hidden">Show/Hide path</br>
	</form>
	</div>
	<!-- end -->
	</body>
	</html>
	queue()
	.defer(d3.xml, "wiggle.svg", "image/svg+xml")
	.await(ready);

	function ready(error, xml) {

	//Adding our svg file to HTML document
	var importedNode = document.importNode(xml.documentElement, true);
	d3.select("#pathAnimation").node().appendChild(importedNode);

	var svg = d3.select("svg");

	var path = svg.select("path#wiggle"),
	startPoint = pathStartPoint(path);

	var checkbox = d3.selectAll("input[name=visibility]");

	checkbox.on("change", function() {
	if (this.checked) {
	path.style("visibility", "visible");
	this.value = "visible";
	} else {
	path.style("visibility", "hidden");
	this.value = "hidden";
	};
	});

	var marker = svg.append("image")
	.attr("xlink:href", "rocket.png")
	.attr("transform", "translate(" + startPoint[0] + "," + startPoint[1] + ")")
	.attr("width", 48)
	.attr("height", 24);

	transition();

	//Get path start point for placing marker
	function pathStartPoint(path) {
	var d = path.attr("d"),
	dsplitted = d.split(" ");
	return dsplitted[1].split(",");
	};

	function transition() {
	marker.transition()
	.duration(17000)
	.attrTween("transform", translateAlong(path.node()))
	.each("end", transition);// infinite loop
	};

	function translateAlong(path) {
	var l = path.getTotalLength();
	var t0 = 0;
	return function(i) {
	return function(t) {
	var p0 = path.getPointAtLength(t0 * l);//previous point
	var p = path.getPointAtLength(t * l);////current point
	var angle = Math.atan2(p.y - p0.y, p.x - p0.x) * 180 / Math.PI;//angle for tangent
	t0 = t;
	//Shifting center to center of rocket
	var centerX = p.x - 24,
	centerY = p.y - 12;
	return "translate(" + centerX + "," + centerY + ")rotate(" + angle + " 24" + " 12" +")";
	}
	}
	}
	}
	path {
	visibility: hidden;
	fill: none;
	stroke: #000;
	stroke-width: 1px;
	}