solar-system/src/js/geometries/RingsGeometry.js

Solar System with Threejs

/*
 * RingsGeometry.js
 * @Description Rings' Planet geometry.
 * @link https://github.com/kdaimiel/solar-system#readme
 * @author Enrique Daimiel Ruiz <k.daimiel@gmail.com>
 * @license MIT License, http://www.opensource.org/licenses/MIT
 */
THREE.RingsGeometry = function (innerRadius, outerRadius, thetaStart, thetaLength, thetaSegments, phiSegments) {

  THREE.Geometry.call( this );

  this.type = 'RingsGeometry';

  this.innerRadius = innerRadius || 0;
  this.outerRadius = outerRadius || 50;

  this.thetaStart = thetaStart !== undefined ? thetaStart : 0;
  this.thetaLength = thetaLength !== undefined ? thetaLength : Math.PI * 2;

  this.thetaSegments = thetaSegments !== undefined ? Math.max( 3, thetaSegments ) : 50;
  this.phiSegments = phiSegments !== undefined ? Math.max( 1, phiSegments ) : 50;

  var i, o, uvs = [], radius = this.innerRadius, radiusStep = ( ( outerRadius - innerRadius ) / this.phiSegments ), segment;
  for ( i = 0; i < this.phiSegments + 1; i ++ ) { // concentric circles inside ring
    for ( o = 0; o < this.thetaSegments + 1; o ++ ) { // number of segments per circle
      var vertex = new THREE.Vector3();
      segment = this.thetaStart + o / this.thetaSegments * this.thetaLength;
      vertex.x = radius * Math.cos( segment );
      vertex.y = radius * Math.sin( segment );

      this.vertices.push( vertex );
      uvs.push( new THREE.Vector2( i/(this.thetaSegments-1), o/ (this.phiSegments-1) ) );
    }
    radius += radiusStep;
  }

  var n = new THREE.Vector3( 0, 0, 1 );
  for ( i = 0; i < this.phiSegments; i ++ ) { // concentric circles inside ring
    var thetaSegment = i * (this.thetaSegments + 1);
    for ( o = 0; o < this.thetaSegments ; o ++ ) { // number of segments per circle
      segment = o + thetaSegment;
      var v1 = segment;
      var v2 = segment + this.thetaSegments + 1;
      var v3 = segment + this.thetaSegments + 2;

      this.faces.push( new THREE.Face3( v1, v2, v3, [ n.clone(), n.clone(), n.clone() ] ) );
      this.faceVertexUvs[ 0 ].push( [ uvs[ v1 ].clone(), uvs[ v2 ].clone(), uvs[ v3 ].clone() ]);

      v1 = segment;
      v2 = segment + this.thetaSegments + 2;
      v3 = segment + 1;

      this.faces.push( new THREE.Face3( v1, v2, v3, [ n.clone(), n.clone(), n.clone() ] ) );
      this.faceVertexUvs[ 0 ].push( [ uvs[ v1 ].clone(), uvs[ v2 ].clone(), uvs[ v3 ].clone() ]);
    }
  }

  this.computeFaceNormals();
  this.boundingSphere = new THREE.Sphere( new THREE.Vector3(), radius );
};

THREE.RingsGeometry.prototype = Object.create( THREE.RingGeometry.prototype );
THREE.RingsGeometry.prototype.constructor = THREE.RingsGeometry;