Program Balloon_Wrap
!    
!	Program to map an unfolded ballon geometry onto a folded configuration (Based on Laroche Paper)
!	Input: File containing nodal coords of ballon geometry (Abaqus INP Format)
!	Output: File containing nodal coords of mapped ballon geometry (Abaqus INP Format)
!	Rev. 1 - J. Grogan - 07/07/10
!
	real pi,x_cor,y_cor,z_cor,theta,radius,theta_hat,rad_hat,alpha,beta,phi
    real inner_radius,outer_radius,num_folds,multiplier
    integer node_num
    logical outer_flap
!	    
	open(unit=10,file='in.dat',status='old')
	open(unit=11,file='out.dat',status='unknown')
!
	pi=acos(-1.)
	inner_radius=0.25
    outer_radius=0.43
    num_folds=3.
    phi=(2*pi)/num_folds
    outer_flap=.false.
!
	do i=1,  9821
  		read(10,*)node_num,x_cor,y_cor,z_cor
  		theta=(atan2(z_cor,x_cor))
        radius=sqrt(z_cor*z_cor+x_cor*x_cor)
!        
  		if(theta<0.)then
    		theta=theta+2*pi
  		endif
!
		beta=(phi/2.)*(1.+(2*radius)/(inner_radius+outer_radius))
        alpha=((outer_radius+inner_radius)/(2*radius))*beta
!
		do j=1,num_folds
        	if((theta>=(j-1)*phi).and.(theta<=(alpha+(j-1)*phi)))then
            	multiplier=j-1
                outer_flap=.true.
            elseif((theta>=(alpha+(j-1)*phi)).and.(theta<=(j*phi)))then
                multiplier=j
                outer_flap=.false.
            endif
        enddo            
!
		if(outer_flap)then
            theta_hat=(beta/alpha)*(theta-multiplier*phi)+multiplier*phi
            rad_hat=inner_radius+((outer_radius-inner_radius)/beta)*(theta_hat-multiplier*phi)
        else
          	theta_hat=((beta-phi)/(phi-alpha))*(multiplier*phi-theta)+multiplier*phi
            rad_hat=inner_radius+((outer_radius-inner_radius)/(beta-phi))*(theta_hat-multiplier*phi)
        endif
!		
     	write(11,*)node_num,',',rad_hat*cos(theta_hat),',',y_cor,',',rad_hat*sin(theta_hat)
    enddo
end program