How to animate multiple circles on a path in d3.js?

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by shyann , in category: Javascript , a month ago

How to animate multiple circles on a path in d3.js?

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1 answer

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by lizzie , a month ago

@shyann 

To animate multiple circles on a path in d3.js, you can use the following steps:

  1. Create a path using the d3.line function to define the path that the circles will follow.
  2. Create a group element (
  3. Bind the data for the circles to the group element using the datum method.
  4. Append a circle element for each data point in the group element.
  5. Set the initial position of each circle on the path using the attr method with the cx and cy attributes.
  6. Use the transition method to animate the circles along the path. You can set the duration and easing function for the animation.


Here is an example code snippet that demonstrates how to animate multiple circles on a path in d3.js:

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// Define the data
const data = [10, 20, 30, 40, 50];

// Create a SVG element
const svg = d3.select("body")
  .append("svg")
  .attr("width", 500)
  .attr("height", 500);

// Define the path
const path = d3.line()([[100, 100], [200, 200], [300, 100], [400, 200], [500, 100]]);

// Create a group element to contain the circles
const group = svg.append("g");

// Bind the data to the group element
group.datum(data);

// Append a circle element for each data point
const circles = group.selectAll("circle")
  .data(data)
  .enter()
  .append("circle")
  .attr("r", 5)
  .attr("fill", "steelblue");

// Set the initial position of each circle on the path
circles.attr("cx", (d, i) => path.getPointAtLength(i / data.length * path.getTotalLength()).x)
  .attr("cy", (d, i) => path.getPointAtLength(i / data.length * path.getTotalLength()).y);

// Animate the circles along the path
circles.transition()
  .duration(2000)
  .attrTween("transform", translateAlongPath(path))
  .ease(d3.easeLinear);

// Function to move the circles along the path
function translateAlongPath(path) {
  return function(d, i, a) {
    return function(t) {
      const point = path.node().getPointAtLength(t * path.node().getTotalLength());
      return "translate(" + point.x + "," + point.y + ")";
    };
  };
}


In this code snippet, we create a path with multiple data points and animate circles moving along the path. The translateAlongPath function calculates the position along the path based on the time t and updates the position of the circles accordingly using the transform attribute.