%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%Function: specify contact geometry entities
%
%input: Problem=0:test problem of two blocks
%               1:Hertz problem
%       Slave_or_Master= 0:slave segment
%                        1:master segment
%
%output: p,n,Xi,P,W=NURBS parameters for the output segment(in 2D, it's a curve)
%        n_q=number of integral points within one element segment
%        patch=the patch number that the segement attached to
%        Global_ID=global ids of the control points on the curve
%        normal_type= 1:normal is 90 anti-clockise to tangent of the curve
%                     2:normal is 90 clockwise to tangent of the curve
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

function [ P, patch, Global_DOF_ID] = Contact_Geometry(Slave_or_Master, dis_1, dis_2)
            global  Nx Ny
            switch Slave_or_Master
                %in problem 0, slave segment is the upper smaller block
                %             which patch=2
                case 0
                    patch=2;
                    [P2,E2,~,~] = Geometry(patch, dis_1, dis_2);
                    P=P2(1:Nx+1, 1:2);%接触面的节点坐标，前五个
                    Global_Node_ID=[1:(Nx+1)]+(Nx+1)*(Ny+1);
                    Global_DOF_ID=[2*(Global_Node_ID(1)-1)+1:2*(Global_Node_ID(end)-1)+2];%接触点对应全局坐标中的索引
                case 1
                    patch=1;
                     [P1,E1,~,~] = Geometry(patch, dis_1, dis_2);
                    P=P1((Nx+1)*Ny+1:(Nx+1)*(Ny+1), 1:2);%接触面的节点，后五个
                    Global_Node_ID=[(Nx+1)*Ny+1:(Nx+1)*(Ny+1)];
                    Global_DOF_ID=[2*(Global_Node_ID(1)-1)+1:2*(Global_Node_ID(end)-1)+2];;%接触点对应全局刚度矩阵中的索引
                   
                otherwise
                    error('Contact_Geometry:slave_or_master can only be chose between 0 or 1');
            end
            
 
          

end