classdef Sphere < handle
% Simple sphere object.
% Used to be fitted to glenoid points.
% 
% This class could be used elsewhere and the constructor
% access might be widen.

  properties
    center = [];
    radius = [];
    residuals = [];
    R2 = [];
    RMSE = [];
  end

  methods
    function obj = Sphere(varargin)
      if nargin == 2
        obj.center = varargin{1};
        obj.radius = varargin{2};
      end
    end

    function fitTo(obj,points)
      [center,radius,residuals,R2] = fitSphere(points);
      obj.center            = center';
      obj.radius            = radius;
      obj.residuals         = residuals;
      obj.R2                = R2;
      obj.RMSE              = norm(residuals)/sqrt(length(residuals));
    end

    function output = isempty(obj)
      output = any(cellfun(@(field)isempty(obj.(field)),fields(obj)));
    end

    function output = polarTangentPoint(obj, polePoint, slicePlaneNormal,...
      polarPointOrientation)
      poleToCenter = Vector(polePoint, obj.center);
      assert(poleToCenter.norm > obj.radius, "Pole point is inside sphere and doesn't have any tangent.");

      poleToCenterPerpendicular = poleToCenter.cross(slicePlaneNormal).orientToward(polarPointOrientation).direction;
      tangentPointAngle = acos(obj.radius/poleToCenter.norm);

      polarTangentPoint = obj.center + ...
        obj.radius*sin(tangentPointAngle)*poleToCenterPerpendicular + ...
        obj.radius*cos(tangentPointAngle)*(-poleToCenter.direction);
      
      output = polarTangentPoint;
    end

    function exportPly(obj, filename)
      sphereToExport = BinarySphere(round(obj.radius), round(obj.center));
      sphereToExport.exportPly(filename);
    end
 
  end

end