3D Line Chart

AddLine3DChart gives each series its own row in depth instead of stacking them all on one plane. That separation is the only reason to pick it: with three or four series whose lines cross each other repeatedly, a flat line chart turns into a tangle, and pushing the series apart makes each one readable again. It costs you the ability to compare values across series at a glance, so the trade is legibility for comparability.

The data shape is identical to the flat chart. Both return LineChartSeries, and the series code can be moved between them unchanged.

Adding the chart

dwng := ss.AddDrawing()
crt, anc := dwng.AddChart(spreadsheet.AnchorTypeTwoCell)
anc.SetWidthCells(10)

lc := crt.AddLine3DChart()
priceSeries := lc.AddSeries()
priceSeries.SetText("Price")
priceSeries.CategoryAxis().SetLabelReference(`'Sheet 1'!A2:A6`)
priceSeries.Values().SetReference(`'Sheet 1'!B2:B6`)

What changes is the axes. A 3D plot needs a third one, the series axis, which is what the depth direction is measured along:

ca := crt.AddCategoryAxis()
va := crt.AddValueAxis()
sax := crt.AddSeriesAxis()
lc.AddAxis(ca)
lc.AddAxis(va)
lc.AddAxis(sax)

ca.SetCrosses(va)
va.SetCrosses(ca)
sax.SetCrosses(va)

Nothing will tell you if you skip it. Workbook.Validate walks the sheets and their cells; it never looks at the charts, so a plot with a missing or unattached axis saves without complaint and only shows up when the file is opened.

AddLine3DChart also installs a 3D view on the chart: 15 degrees of X rotation, 20 degrees of Y, right-angle axes off, and floor, side wall and back wall all at zero thickness. Those are set on the chart, not the plot, so adding a second plot type to the same chart inherits them.

Limitations

There is no exported setter for the viewing angle. Changing it means reaching into crt.X().Chart.View3D and setting RotX, RotY or Perspective on the wrapped XML.

The 3D series is filled as well as outlined. Line3DChart.AddSeries applies the palette color to both the line properties and the shape properties, where the flat LineChart.AddSeries sets only the line, so a series you style yourself needs both overriding.

Depth ordering follows series index. There is no way to reorder the rows other than adding the series in the order you want them, or calling SetOrder on the series afterwards.

Run the example

The example is the flat line chart example with AddLine3DChart and a series axis substituted in, which makes it a useful diff to read side by side.

git clone https://github.com/unidoc/unioffice-examples.git
cd unioffice-examples/spreadsheet/line-chart-3d
go run main.go

If this is your first time using UniOffice, follow the getting started guide to create an API key and set up your development environment.

Sample output