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A common goal in Calcs Builder is to show a simple shape on the sheet, for example a rectangle whose sides come from the user’s width and length (or similar inputs). To do that, you do not use only a diagram widget. You set up two parts that work like “sketch the shape, then show the picture”:
  1. A Remote widget that runs the section properties solver (this turns your rectangle definition into real drawing data).
  2. A Diagram widget with a Cross section layer (this draws what the first step returned).
The sections below use a rectangle as the running example, then explain why this two-step pattern exists.

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At a glance: who does what?

StepWhat you addIn plain terms
1Remote (solver: sectionProperties)“Here is my shape (sectionsData), please build the outline I can plot.”
2Diagram (type crossSection)“Take the result from step 1 and put it on the page (lines, box, labels).”
Remote is the step that computes the outline. Diagram is the viewer on the sheet. If you only put the rectangle definition on the diagram and skip the remote, the cross-section view has nothing to draw (no lines yet), so the plot can stay empty.
This is the same idea as many steel/timber modules: the section is solved first; the small preview uses solved geometry, not the raw sectionsData by itself.

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Example: how to set up a rectangle

Here is a typical setup so the user enters width and length, and the sheet shows a rectangular cross-section plot.
1

1. Add two inputs and give them reference IDs

For example, add an input for width and one for length (or whatever you want to label them).Give each widget a clear reference ID you will use in math, for example W and L. Those are the names your equations will see (the symbol shown in the UI can still be a longer label if you prefer).
Inputs W and L
2

2. Add a Remote widget and pick the section properties solver

  • Solver: sectionProperties
  • Reference ID: pick one name and stick to it everywhere below, for example xsect
Remote Widget
In the equation (usually one row, condition @default), set the result to an object that:
  • describes the rectangle in sectionsData, using your inputs (depth/width for a Rect are d and b, match them to your width/length);
  • sets lenUnit to match your inputs (for example "ft" if the user types feet);
  • for outline only, you can set analysisType to none so the solver just prepares the drawing, not a full property run.
Shape of the result (simplified):
{
  sectionsData: [{ type: "Rect", d: W, b: L }],
  analysisType: "none",
  lenUnit: "ft"
}
Adjust W and L to match your actual reference IDs and your unit string if different.
3

3. Add a Diagram widget with Cross section

  • Add a Diagram from the widget palette.
  • In the diagram settings, set the type to cross section (one layer).
Diagram Widget Diagram Data
In the equation (again often @default), the result should read from the remote you named in step 2, not re-define the rectangle. Point at the solved outline:
{
  lines: xsect.lines,
  dimensions: xsect.dimensions,
  domain: xsect.domain,
  height: 200,
  lenUnit: "ft",
  lenConvert: 1
}
Diagram Widget Equation
The name you use in the diagram (for example xsect in xsect.lines) must be the same reference ID you gave the remote in step 2. If the remote is xsect, use xsect.lines, and so on. If you named the remote myShape, use myShape.lines, and so on.
4

4. Preview the template

Change the width and length. The remote re-runs, then the diagram updates. If the plot is blank, double-check the names in step 3 and that the remote’s equation is not empty (see Troubleshooting).
A rectangle in sectionsData often uses the Rect type with two side lengths, d and b. You decide which user input maps to which, for example width to d and length to b, as long as it matches your plan or section convention.

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Why you can’t do it in one diagram step

The cross section layer on a diagram is a display. It expects the same data our solvers use for a finished outline: polylines (lines), a bounding area (domain), and optional dimensions. That data is produced when the section properties solver ingests your sectionsData. The diagram does not re-run that full process inside the widget, so the remote step is required to go from “I want a Rect” to “here are the lines to draw”.

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If your section is already solved somewhere else

Some modules already feed a solved section (for example a linked or database member). Then the diagram might only reference an existing object (e.g. xsect.lines with xsect defined earlier). The rule is unchanged: the diagram always plots solved lines and domain, not the raw sectionsData on its own.

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Troubleshooting (builder)

The result on that equation row is actually blank. Fix the row so it has a full result string, or remove unused rows. This is a validation message, not a complaint about the geometry yet.
  1. Confirm the Remote is saved with sectionProperties, non-empty result, and a reference ID.
  2. In the Diagram equation, use that exact name: myRef.lines, myRef.dimensions, myRef.domain (e.g. xsect.lines if the remote is xsect).
  3. Check lenUnit and lenConvert match the units you use in inputs.
Equations use reference IDs (e.g. W, L, xsect), the names you set in the builder, not a fake @ syntax. Mismatches here fail when the sheet evaluates, not as “empty result.”

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See also

Remote widget

Solvers, payloads, and referenceId

Diagram widget

Legacy diagrams, including cross sections
End users of a published calc usually only see the inputs and the picture. The remote and diagram split is mainly for template authors setting this up in Calcs Builder.