How do I use vertical orientation

Hi,

I don't have access to source code which was used to create your barchart visual.

Now I may be wrong... though I can assume this type of barchart may have been built using d3.js

coding approach. Actually a lot of visuals found Custom Visual Gallery were basically built using

a d3.js coding approach including the main barChart tutorial found on Github.

So I'd say that pretty often label orientation can be dealt with transform rotate attribute.

As an example  the following code with x-axis label 

 svg.append("g")
                .attr("class", "x axis")
                .attr("transform", "translate(0," + height + ")")
                .call(xAxis)
                .selectAll("text")
                .style("text-anchor", "end")
                .attr("dx", "-.8em")
                .attr("dy", "-.55em")
                .attr("transform", "rotate(-90)" ); //<---- 90 angle rotation

would produce something similar to this

while the same code with only minor rotate parameter modification:

svg.append("g")
                .attr("class", "x axis")
                .attr("transform", "translate(0," + height + ")")
                .call(xAxis)
                .selectAll("text")
                .style("text-anchor", "end")
                .attr("dx", "-.8em")
                .attr("dy", "-.55em")
                .attr("transform", "rotate(-45)" ); //<-- 45 angle rotation

would render something similar to this:

Note that this is pretty basic d3.js stuff... if you can send a copy of the source code you're using
then  I maybe I could take a closer look at it and come up with something more accurate...

Hope this helps