Draw A Fan Between Vectors a & b

DrawFan.cs

void DrawFan(Vector3 o, Vector3 a, Vector3 b, uint numSegments)
{
  a.Normalize();
  b.Normalize();

  Vector3 axis = Vector3.Cross(a, b);
  float angle = Mathf.Acos(Vector3.Dot(a, b)) * Mathf.Rad2Deg;
  float deltaAngle = angle / numSegments;
  Quaternion q = Quaternion.AngleAxis(deltaAngle, axis);

  Vector3 p0 = a;
  for (uint i = 0; i < numSegments; ++i)
  {
    Vector3 p1 = p0;
    p0 = q * p0;
    DrawTriangle(0, p1, p0);
  }
}