Cylinder constructor

Cylinder({ double radiusTop = 1, double radiusBottom = 1, double height = 1, int numSegments = 8, })

@param radiusTop The radius of the top of the Cylinder. @param radiusBottom The radius of the bottom of the Cylinder. @param height The height of the Cylinder. @param numSegments The number of segments to build the cylinder out of.

Implementation

Cylinder({
  this.radiusTop = 1,
  this.radiusBottom = 1,
  this.height = 1,
  this.numSegments = 8
}):super(type: ShapeType.cylinder){
  if (radiusTop < 0) {
    throw('The cylinder radiusTop cannot be negative.');
  }

  if (radiusBottom < 0) {
    throw('The cylinder radiusBottom cannot be negative.');
  }

  final int N = numSegments;
  List<int> bottomface = [];
  List<int> topface = [];
  List<Vec3> axes =[];

  vertices = [];
  faces = [];
  // First bottom point
  vertices.add(Vec3(-radiusBottom * math.sin(0), -height * 0.5, radiusBottom * math.cos(0)));
  bottomface.add(0);

  // First top point
  vertices.add(Vec3(-radiusTop * math.sin(0), height * 0.5, radiusTop * math.cos(0)));
  topface.add(1);

  for (int i = 0; i < N; i++) {
    final theta = ((2 * math.pi) / N) * (i + 1);
    final thetaN = ((2 * math.pi) / N) * (i + 0.5);
    if (i < N - 1) {
      // Bottom
      vertices.add(Vec3(-radiusBottom * math.sin(theta), -height * 0.5, radiusBottom * math.cos(theta)));
      bottomface.add(2 * i + 2);
      // Top
      vertices.add(Vec3(-radiusTop * math.sin(theta), height * 0.5, radiusTop * math.cos(theta)));
      topface.add(2 * i + 3);

      // Face
      faces.add([
        2 * i,
        2 * i + 1,
        2 * i + 3,
        2 * i + 2
      ]);
    } else {
      faces.add([
        2 * i,
        2 * i + 1,
        1,
        0
      ]); // Connect
    }

    // Axis: we can cut off half of them if we have even number of segments
    if (N % 2 == 1 || i < N / 2) {
      axes.add(Vec3(-math.sin(thetaN), 0, math.cos(thetaN)));
    }
  }
  faces.add(bottomface);
  axes.add(Vec3(0, 1, 0));

  // Reorder top face
  List<int> temp = [];
  for (int i = 0; i < topface.length; i++) {
    temp.add(topface[topface.length - i - 1]);
  }
  faces.add(temp);

  type = ShapeType.cylinder;
  radiusTop = radiusTop;
  radiusBottom = radiusBottom;
  height = height;
  numSegments = numSegments;

  init(vertices, faces, faceNormals, axes, boundingSphereRadius);
}