[2.1] Blueprint snap-to-grid inputs should support math expressions

[werecat]

Since 2.0, most numeric input fields in Factorio support math expressions, for instance (3+5)*4 or 3k/6. However the grid size parameters on blueprints are an exception to this and only allow exact values.

Why I think this is important
Often when I'm making a blueprint, I need to capture "extra parts" outside of the main desired "grid", generally for beacons or belt connections. Currently the only way to cut the grid to the proper size is to manually calculate the proper "width" and "height" value you want before hand and then enter those values. However if math expressions were supported and for example you knew you needed to subtract 9 from the width, you could simply write -9 at the end of the current value and the proper width would automatically be calculated. Alternatively players could "work forward" with an expression like 3 * 4, 3 being the machine size and 4 being the machine count in the example picture.

Extra considerations
Currently the grid size parameters update the bounding box in the blueprint preview immediately upon any value change. If math expressions are supported, the bounding box would have to wait until the user presses enter/otherwise confirm before calculating and updating the preview

Example blueprint

07-23-2026, 15-04-59.png (504.53 KiB) Viewed 167 times

[eugenekay]

Since 2.0, most numeric input fields in Factorio support math expressions, for instance (3+5)*4 or 3k/6. However the grid size parameters on blueprints are an exception to this and only allow exact values.

A (non-exhaustive) list of other Numerical inputs that do not support Expressions:

• Settings menu
• Logistic Group multiplier factors
• Selector Combinator - Random input mode "Update interval"
• Editor mode "extra settings" dialogs
• Electric Energy Interface
• Inserter "Override stack size"
• Train stop "train limit" and "Priority"
• Train Schedule "Time passed" condition
• Decider Combinator "Set constant" (for Outputs)

In fact, it seems like the only place where Expressions are accepted is when inputting "Or set a constant" instead of a Signal... Should this feature be removed for consistency?

Good Luck!