CODEWITHSUNDEEP
javascriptsvgd3.jsanglelinear-gradients
Rafael
Rafael

Reputation: 5129

dynamically angle linear gradient of svg

I am dynamically adding linear gradients to each path within a circular diagram. I want each gradient to split each path down the middle. Like so:

image alt

I know I am able to rotate the gradient using gradientTransform but the rotation is different depending on the path's location within the circular diagram. How can I calculate the paths angle and draw the linear gradient accordingly? I have also tried manipulating the x1, x2, y1, and y2 coordinates of the linear gradient, but I'm not sure how to manipulate them accordingly.

let data = {
  name: "demo",
  children: [{
      "ID": "001",
      "Games": "PS2",
      "children": [{
        "ID": "001-1",
        "Games": "PS2",
      }]
    },
    {
      "ID": "002",
      "Games": "PS2",
      "children": [{
        "ID": "002-2",
        "Games": "PS2",
      }]
    },
    {
      "ID": "003",
      "Games": "PS2",
      "children": [{
        "ID": "003-1",
        "Games": "PS2",
      }]
    },
    {
      "ID": "004",
      "Games": "PS2",
      "children": [{
        "ID": "004-1",
        "Games": "PS2",
      }]
    },
    {
      "ID": "005",
      "Games": "PS2",
      "children": [{
        "ID": "005-5",
        "Games": "PS2",
      }]
    }
  ]
}


let width = 500;
let height = 500;
let radius = Math.min(width, height) / 2;
let color = d3.scaleOrdinal(d3.schemeCategory20b);

let g = d3.select('svg')
  .attr('width', width)
  .attr('height', height)
  .append('g')
  .attr('transform', 'translate(' + width / 2 + ',' + height / 2 + ')');

// Data strucure
let partition = d3.partition()
  .size([2 * Math.PI, radius]);

// Find data root
let root = d3.hierarchy(data)
  .sum(function(d) {
    return !d.children || d.children.length === 0 ? 2 : 0
  });

// Size arcs
partition(root);
let arc = d3.arc()
  .startAngle(function(d) {
    return d.x0
  })
  .endAngle(function(d) {
    return d.x1
  })
  .innerRadius(function(d) {
    return d.y0
  })
  .outerRadius(function(d) {
    return d.y1
  });

let svg = d3.select('svg')
// Put it all together
g.selectAll('path')
  .data(root.descendants())
  .enter().append('path')
  .attr("stroke-width", "5")
  .each((d, i, m) => {
    let lg = svg.append("defs")
      .append("linearGradient")
      .attr("id", `gradient${d.data.ID}`)
      .attr("gradientTransform", `rotate(${0})`)
      .attr("x1", "0%")
      .attr("x2", "100%")
      .attr("y1", "0%")
      .attr("y2", "0%")

    lg.append("stop")
      .attr("offset", "50%")
      .attr("stop-color", "#188F6B")

    lg.append("stop")
      .attr("offset", "50%")
      .attr("stop-color", "#3BDBAB")
  })
  .style("fill", (d) => {
    return `url(#gradient${d.data.ID})`
  })
  .attr("display", function(d) {
    return d.depth ? null : "none";
  })
  .attr("d", arc)
  .style('stroke', '#fff')
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/5.7.0/d3.min.js"></script>

<svg></svg>

Upvotes: 2

Views: 717

Answers (1)

enxaneta
enxaneta

Reputation: 33024

This is my solution: I'm using only one gradient and 2 paths. The two one where the result is what you need. I'm grouping the 2 paths in a group with an id so that I can reuse it as many times as I need.

This will simplify your code a lot. Please observe that I'm moving the style and all the attributes to the group since they are the same. You don't need to repeat yourself.

Since the group is 1/5 of a circle this meant the spread angle of the group is 72º

I'm reusing the group 4 times rotating the use element 172 degs, 272 degs, 372 degs and 472 degs.

Since the drawing is centered around the point {x:0,y:0} you don't need to add a rotation center.

<svg width="500" height="500" viewBox="-250 -250 500 500">
  <g id="theG" style="fill: url(#gradient); stroke: rgb(255, 255, 255);"  stroke-width="5">
    <path d="M97.96420871541218,134.8361657291579A166.66666666666666,166.66666666666666,0,0,1,-97.96420871541217,134.8361657291579L-48.982104357706085,67.41808286457895A83.33333333333333,83.33333333333333,0,0,0,48.98210435770609,67.41808286457895Z" ></path>
    <path  d="M146.9463130731183,202.25424859373686A250,250,0,0,1,-146.94631307311826,202.25424859373686L-97.96420871541217,134.8361657291579A166.66666666666666,166.66666666666666,0,0,0,97.96420871541218,134.8361657291579Z"></path>
</g>
  
  <use xlink:href="#theG" transform="rotate(72)" />
  <use xlink:href="#theG" transform="rotate(144)" />
  <use xlink:href="#theG" transform="rotate(216)" />
  <use xlink:href="#theG" transform="rotate(288)" />
  
  <defs>
    <linearGradient id="gradient" gradientTransform="rotate(0)" x1="0%" x2="100%" y1="0%" y2="0%">
      <stop offset="50%" stop-color="#188F6B"></stop>
      <stop offset="50%" stop-color="#3BDBAB"></stop>
    </linearGradient>
  </defs>
 
</svg>

Upvotes: 3

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