package.src.symbol.star.js Maven / Gradle / Ivy

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Graphical primitives for visualization, such as lines and areas.

There is a newer version: 3.2.0

import {pi, tau} from "../math";

var ka = 0.89081309152928522810,
    kr = Math.sin(pi / 10) / Math.sin(7 * pi / 10),
    kx = Math.sin(tau / 10) * kr,
    ky = -Math.cos(tau / 10) * kr;

export default {
  draw: function(context, size) {
    var r = Math.sqrt(size * ka),
        x = kx * r,
        y = ky * r;
    context.moveTo(0, -r);
    context.lineTo(x, y);
    for (var i = 1; i < 5; ++i) {
      var a = tau * i / 5,
          c = Math.cos(a),
          s = Math.sin(a);
      context.lineTo(s * r, -c * r);
      context.lineTo(c * x - s * y, s * x + c * y);
    }
    context.closePath();
  }
};