使用canvas绘制任意大小任意边的五角星

1.gif

/**
   * @description: 星形
   * @param {number} n 边数 3-n
   * @param {number} r1 大圈
   * @param {number} r2 小圈
   */
star(n: number, rx1: number, rx2: number, ry1: number, ry2: number) {
    const points = []
    const cor = 360 / n / 2
    const rightAngle = n % 2 === 0 ? 360 / n : 360 / (n * 2)
    for (let i = 0; i <= n; i++) {
      const x1 = rx1 * Math.sin(((rightAngle + 2 * i * cor) / 180) * Math.PI)
      const y1 = ry1 * Math.cos(((rightAngle + 2 * i * cor) / 180) * Math.PI)
      //画第二条边
      const x2 = rx2 * Math.sin(((rightAngle + (2 * i + 1) * cor) / 180) * Math.PI)
      const y2 = ry2 * Math.cos(((rightAngle + (2 * i + 1) * cor) / 180) * Math.PI)
      points.push({ x: x1, y: y1 })
      if (i !== n) {
        points.push({ x: x2, y: y2 })
      }
    }
    return { points }
}

调用

this.star(5, width / 2, (width / 2) * 0.4, height / 2, (height / 2) * 0.4)