%
% volOut = volume_merge_logical_MSBackground( volA, volB )
% -------------------------------------------------------------------------
%
%   Logical combinations of 3-D arrays.
%   Purpose modified for merging foreground and background of "Mixed symmetry" 
%   animation.
%
% INPUT:
%
%   volA, volB    - 3-D arrays.
%                   Note: Currently all dimensions must be equal.
%
% HARDCODED (immediately below function declaration):
%
%   none           - none
%
% RETURN VALUES:
%
%   volOut    - Grayscale volume array with size the same as input arrays. 
%
% FUNCTION CALLS and DEPENDENCIES: 
%
%
% Mark Dow,             November 23, 2008
% Mark Dow, modified    November .., 2008 ()
%
%
%   TERMS FOR USE: There are no restrictions on the use of this code, 
%                  auxilliary code and other required resources. Claiming 
%                  to be the originator, explicitly or implicitly, is bad  
%                  karma. A link (if appropriate), a note to dow[at]uoregon.edu, 
%                  and credit are appreciated but not required.
%

function volOut = volume_merge_logical_MSBackground( volA, volB )

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% hardcoded parameters


% hardcoded parameters
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% To Do: Sanity check dimensions of volumes. Currently only accomodates equal
% dimensions.

    DIM = size( volA );
    volOut = zeros( size( volA ) );
    
    for i = 1 : DIM( 1 )
    for j = 1 : DIM( 2 )
    for k = 1 : DIM( 3 )
        
        % If partial occlusion:
        % Detect partial front edge:
        bPartEdge = 0;
        bZeroNbr  = 0;
        
        maxNbr = 0;
        if i - 1 >= 1
            maxNbr = max( volA( i - 1, j, k     ), volA( i - 1, j, k     )  );
            if volA( i - 1, j, k    ) < .0001
                bZeroNbr = 1;
            end
        end
        if i + 1 <= DIM( 1 )
            maxNbr = max( volA( i + 1, j, k     ), maxNbr  );
            if volA( i + 1, j, k    ) < .0001
                bZeroNbr = 1;
            end
        end
        if k - 1 >= 1
            maxNbr = max( volA( i    , j, k - 1 ), maxNbr  );
            if volA( i   , j, k - 1 ) < .0001
                bZeroNbr = 1;
            end
        end
        if k + 1 <= DIM( 3 )
            maxNbr = max( volA( i    , j, k + 1 ), maxNbr  );
            if volA( i   , j, k + 1 ) < .0001
                bZeroNbr = 1;
            end
        end

        if    maxNbr - volA(i,j,k) > .05 ...
           && bZeroNbr
            bPartEdge = 1;
        end

        if bPartEdge && volA(i,j,k) > volB(i,j,k) %&& volB(i,j,k) > 0.0001   %...
            % subtract fraction distance from foreground to background
            volOut(i,j,k) = volA(i,j,k) - ( volA(i,j,k) - volB(i,j,k) )*( ( maxNbr - volA(i,j,k) )/( maxNbr - volB(i,j,k) ) ); %+ ( volA(i,j,k) - volB(i,j,k) )/2;
        else
            if volB(i,j,k) > 0
                volOut(i,j,k) = volB(i,j,k);
            end
            if volA(i,j,k) > 0 && volA(i,j,k) > volB(i,j,k)
                volOut(i,j,k) = volA(i,j,k);
            end
        end
        
    end
    end
    end