// The Coding Train / Daniel Shiffman

// https://thecodingtrain.com/CodingChallenges/008-solarsystemgenerator3d.html

// https://youtu.be/dncudkelNxw

// https://editor.p5js.org/codingtrain/sketches/QIB-sT10

​

class Planet {

  constructor(r, d, o) {

    this.v = p5.Vector.random3D();

​

    this.radius = r;

    this.distance = d;

    this.v.mult(this.distance);

    this.angle = random(TWO_PI);

    this.orbitspeed = o;

​

    this.planets = null;

  }

​

  orbit() {

    this.angle = this.angle + this.orbitspeed;

    if (this.planets != null) {

      for (let i = 0; i < this.planets.length; i++) {

        this.planets[i].orbit();

      }

    }

  }

​

  spawnMoons(total, level) {

    this.planets = [];

    for (let i = 0; i < total; i++) {

      let r = this.radius / (level * 2);

      let d = random(this.radius + r, (this.radius + r) * 2);

      let o = random(-0.1, 0.1);

      this.planets[i] = new Planet(r, d, o);

      if (level < 2) {

        let num = int(random(0, 3));

        this.planets[i].spawnMoons(num, level + 1);

      }

    }

  }

​

  show() {

    push();

    noStroke();

    let v2 = createVector(1, 0, 1);

    let p = this.v.cross(v2);

    // Rotation around a 0-length axis doesn't work in p5.js, so don't do that.

    if (p.x != 0 || p.y != 0 || p.z != 0) {

      rotate(this.angle, p);

    }

    stroke(255);

    //line(0, 0, 0, this.v.x, this.v.y, this.v.z);

    //line(0, 0, 0, p.x, p.y, p.z);

​

    translate(this.v.x, this.v.y, this.v.z);

    noStroke();

    fill(255);

    sphere(this.radius);

    //ellipse(0, 0, this.radius * 2, this.radius * 2);

    if (this.planets != null) {

      for (let i = 0; i < this.planets.length; i++) {

        this.planets[i].show();

      }

    }

    pop();

  }

}