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Parameters and expressions
Every dimension and feature input is a model parameter (d1, d2, …). User parameters
are ones you add yourself, with a unit, an expression and an optional comment. Change them in
Change Parameters (parameters.change). The timeline rebuilds from the first feature that
uses them.
Expressions are unit-aware: 2 * width + 5 mm, angle / 2, sqrt(area), 1 in + 3 mm, using
+ - * / ^, parentheses, sin cos tan asin acos atan atan2 sqrt abs min max floor ceil round mod trunc and unit conversion. A length where an angle is expected (or the other way round) is an
error, not a silent conversion. Cycles are reported with their path (a → b → a), renaming a
parameter updates every expression, dimension and feature input that uses it, and a parameter
in use can't be deleted (the error lists its users).
The design's units (Document Settings in the browser: mm, cm, m, in or ft) set how a bare number
typed into a feature is read. In an inch design 2 means 2 in. Changing the units never moves
existing geometry.
Parameters export to and import from CSV or JSON (parameters.export, parameters.import).
Configurations (config.*) keep a table of rows, each with its own parameter values and
suppressed features, physical materials and body appearances, switched with config.activate.
The table's Library picker selects material or appearance values. Choose Follow material
to clear an appearance override. Custom looks retain their colour and opacity across
activation, undo and save/reopen. See
configuration commands and examples.