CircleGeometry constructor

CircleGeometry({ dynamic radius = 1, dynamic segments = 8, dynamic thetaStart = 0, dynamic thetaLength = Math.PI * 2, })

Implementation

CircleGeometry(
    {radius = 1, segments = 8, thetaStart = 0, thetaLength = Math.PI * 2})
    : super() {
  type = 'CircleGeometry';

  parameters = {
    "radius": radius,
    "segments": segments,
    "thetaStart": thetaStart,
    "thetaLength": thetaLength
  };

  segments = Math.max<num>(3, segments);

  // buffers

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

  // helper variables

  var vertex = Vector3();
  var uv = Vector2(null, null);

  // center point

  vertices.addAll([0, 0, 0]);
  normals.addAll([0, 0, 1]);
  uvs.addAll([0.5, 0.5]);

  for (var s = 0, i = 3; s <= segments; s++, i += 3) {
    var segment = thetaStart + s / segments * thetaLength;

    // vertex

    vertex.x = radius * Math.cos(segment);
    vertex.y = radius * Math.sin(segment);

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

    // normal

    normals.addAll([0.0, 0.0, 1.0]);

    // uvs

    uv.x = (vertices[i] / radius + 1) / 2;
    uv.y = (vertices[i + 1] / radius + 1) / 2;

    uvs.addAll([uv.x.toDouble(), uv.y.toDouble()]);
  }

  // indices

  for (var i = 1; i <= segments; i++) {
    indices.addAll([i, i + 1, 0]);
  }

  // build geometry

  setIndex(indices);
  setAttribute('position',
      Float32BufferAttribute(Float32Array.from(vertices), 3, false));
  setAttribute('normal',
      Float32BufferAttribute(Float32Array.from(normals), 3, false));
  setAttribute(
      'uv', Float32BufferAttribute(Float32Array.from(uvs), 2, false));
}