3D boxes

splot with boxes requires at least 3 columns of input data. Additional input columns may be used to provide information such as box width or fill color.

     3 columns:  x  y  z
     4 columns:  x  y  z  [x_width or color]
     5 columns:  x  y  z  x_width  color

The last column is used as a color only if the splot command specifies a variable color mode. Examples

     splot 'blue_boxes.dat' using 1:2:3 fc "blue"
     splot 'rgb_boxes.dat' using 1:2:3:4 fc rgb variable
     splot 'category_boxes.dat' using 1:2:3:4:5 lc variable

In the first example all boxes are blue and have the width previously set by set boxwidth. In the second example the box width is still taken from set boxwidth because the 4th column is interpreted as a 24-bit RGB color. The third example command reads box width from column 4 and interprets the value in column 5 as an integer linetype from which the color is derived.

By default boxes have no thickness; they consist of a single rectangle parallel to the xz plane at the specified y coordinate. You can change this to a true box with four sides and a top by setting a non-zero extent on y. See set boxdepth.

3D boxes are processed as pm3d quadrangles rather than as surfaces. Because of this the front/back order of drawing is not affected by set hidden3d. Similarly if you want each box face to have a border you must use set pm3d border rather than set style fill border. See set pm3d. For best results use a combination of set pm3d depthorder base and set pm3d lighting.