It is perfectly possible to combine the previous bar types to have grouped accumulated bar plots. This is done by just adding the different accumulated plots to a group bar plot, for example the following code would do that.
// Create all the 4 bar plots
$b1plot
= new BarPlot($data1y);
$b1plot->SetFillColor(
"orange");
$b2plot
= new BarPlot($data2y);
$b2plot->SetFillColor(
"blue");
$b3plot
= new BarPlot($data3y);
$b3plot->SetFillColor(
"green");
$b4plot
= new BarPlot($data4y);
$b4plot->SetFillColor(
"brown");
// Create the accumulated bar plots
$ab1plot
= new AccBarPlot
(array($b1plot
,$b2plot));
$ab2plot
= new AccBarPlot
(array($b3plot
,$b4plot));
// Create the grouped bar plot
$gbplot
= new GroupBarPlot
(array($ab1plot
,$ab2plot));
// ...and add it to the graph
$graph->Add(
$gbplot);
Putting this together in an example would then produce the graph as shown below