TorusGeometry constructor

TorusGeometry([ double radius = 1, double tube = 0.4, int radialSegments = 8, int tubularSegments = 6, double arc = math.pi * 2, ])

radius - Radius of the torus, from the center of the torus to the center of the tube. Default is 1.

tube — Radius of the tube. Default is 0.4.

radialSegments — Default is 12

tubularSegments — Default is 48.

arc — Central angle. Default is pi * 2.

Implementation

TorusGeometry([
  double radius = 1,
  double tube = 0.4,
  int radialSegments = 8,
  int tubularSegments = 6,
  double arc = math.pi * 2
]):super() {
  type = "TorusGeometry";
  parameters = {
    "radius": radius,
    "tube": tube,
    "radialSegments": radialSegments,
    "tubularSegments": tubularSegments,
    "arc": arc
  };

  // buffers

  List<int> indices = [];
  List<double> vertices = [];
  List<double> normals = [];
  List<double> uvs = [];

  // helper variables

  final center = Vector3.zero();
  final vertex = Vector3.zero();
  final normal = Vector3.zero();

  // generate vertices, normals and uvs

  for (int j = 0; j <= radialSegments; j++) {
    for (int i = 0; i <= tubularSegments; i++) {
      final u = i / tubularSegments * arc;
      final v = j / radialSegments * math.pi * 2;

      // vertex

      vertex.x = (radius + tube * math.cos(v)) * math.cos(u);
      vertex.y = (radius + tube * math.cos(v)) * math.sin(u);
      vertex.z = tube * math.sin(v);

      vertices.addAll(
          [vertex.x.toDouble(), vertex.y.toDouble(), vertex.z.toDouble()]);

      // normal

      center.x = radius * math.cos(u);
      center.y = radius * math.sin(u);
      normal.sub2(vertex, center).normalize();

      normals.addAll(
          [normal.x.toDouble(), normal.y.toDouble(), normal.z.toDouble()]);

      // uv

      uvs.add(i / tubularSegments);
      uvs.add(j / radialSegments);

      if(i > 0 && j > 0){
        final a = (tubularSegments + 1) * j + i - 1;
        final b = (tubularSegments + 1) * (j - 1) + i - 1;
        final c = (tubularSegments + 1) * (j - 1) + i;
        final d = (tubularSegments + 1) * j + i;

        indices.addAll([a,b,d]);
        indices.addAll([b,c,d]);
      }
    }
  }

  // generate indices

  // for (int j = 1; j <= radialSegments; j++) {
  //   for (int i = 1; i <= tubularSegments; i++) {
  //     // indices

  //     final a = (tubularSegments + 1) * j + i - 1;
  //     final b = (tubularSegments + 1) * (j - 1) + i - 1;
  //     final c = (tubularSegments + 1) * (j - 1) + i;
  //     final d = (tubularSegments + 1) * j + i;

  //     // faces

  //     indices.addAll([a, b, d]);
  //     indices.addAll([b, c, d]);
  //   }
  // }

  // build geometry

  setIndex(indices);
  setAttribute(Attribute.position, Float32BufferAttribute.fromList(vertices, 3));
  setAttribute(Attribute.normal, Float32BufferAttribute.fromList(normals, 3));
  setAttribute(Attribute.uv, Float32BufferAttribute.fromList(uvs, 2));
}