modeling/src/primitives/circle.js

  1. const { TAU } = require('../maths/constants')
  3. const ellipse = require('./ellipse')
  5. const { isGTE } = require('./commonChecks')
  7. /**
  8.  * Construct a circle in two dimensional space where all points are at the same distance from the center.
  9.  * @see [ellipse]{@link module:modeling/primitives.ellipse} for more options
  10.  * @param {Object} [options] - options for construction
  11.  * @param {Array} [options.center=[0,0]] - center of circle
  12.  * @param {Number} [options.radius=1] - radius of circle
  13.  * @param {Number} [options.startAngle=0] - start angle of circle, in radians
  14.  * @param {Number} [options.endAngle=TAU] - end angle of circle, in radians
  15.  * @param {Number} [options.segments=32] - number of segments to create per full rotation
  16.  * @returns {geom2} new 2D geometry
  17.  * @alias module:modeling/primitives.circle
  18.  * @example
  19.  * let myshape = circle({radius: 10})
  20.  */
  21. const circle = (options) => {
  22.   const defaults = {
  23.     center: [0, 0],
  24.     radius: 1,
  25.     startAngle: 0,
  26.     endAngle: TAU,
  27.     segments: 32
  28.   }
  29.   let { center, radius, startAngle, endAngle, segments } = Object.assign({}, defaults, options)
  31.   if (!isGTE(radius, 0)) throw new Error('radius must be positive')
  33.   radius = [radius, radius]
  35.   return ellipse({ center, radius, startAngle, endAngle, segments })
  36. }
  38. module.exports = circle