% 
% MATLAB script for visualization of scalar field data
% Latest update: 2014.1.10
%
% ---------- How to execute ----------
% >> run('visualize_scalarfield3d')
% ------------------------------------
%
function visualize_scalarfield3d()
    fid=fopen('scalar_field_3d.dat','rb');
    data = fread(fid,[4,inf],'double');
    
    % ========== definition of uniform grid ==========
    xmax = 5.0;
    ymax = 5.0;
    zmax = 5.0;
    xmin = 0.0;
    ymin = 0.0;
    zmin = 0.0;
    dx = 0.1;
    [xq yq zq] = meshgrid(xmin:dx:xmax,ymin:dx:ymax,zmin:dx:zmax); 
    % ================================================

    % ========== read data ==========
    %
    % data(1,:) = x, data(2,:) = y, data(3,:) = z, data(4,:) = f(x,y,z)
    %
    vq = griddata3(data(1,:),data(2,:),data(3,:),data(4,:),xq,yq,zq);
    
    mx = (xmax-xmin)/2.0;
    my = (ymax-ymin)/2.0;
    mz = (zmax-zmin)/2.0;
    h = slice(xq,yq,zq,vq,[mx],[my],[mz]);
    % ===============================
    
    % ----- draw colormap -----
    set(h,'EdgeColor','none');
    alpha('color')
    alphamap('increase',.3)
    % -------------------------

    axis([xmin xmax ymin ymax zmin zmax]); 
    
    ylabel('y', ... 
        'FontWeight','b','Color','b', ... 
        'VerticalAlignment','bottom');  % boldface blue 
    xlabel('x', ... 
        'FontWeight','b','Color','b', ... 
        'VerticalAlignment','bottom');  % boldface blue 
    zlabel('z', ... 
        'FontWeight','b','Color','b', ... 
        'VerticalAlignment','bottom');  % boldface blue 

    colorbar % colorbar on the right side

    fclose(fid);
end