Monday, 28 March 2011

Setting a +/- Offset in a Revit Family

Have you ever run into an issue where you needed to enter a negative offset value within a family and got an error? If you haven't... you will.

Here's a nice tip from Bruce Madsen in the San Francisco office that was used to allow for a quick positive or negative distance value to adjust curtain panel offsets:

The problem is that Revit does not allow negative distances:
When a negative distance is entered, Revit will report, “Parameter <name> has an invalid value.”

Create the Offset parameter as a number and use an IF statement to control the length – and to convert the number to a distance.

Steps to Follow:
  1. Create a “Number” type parameter for the offset dimension
    • “MyOffset_Inches”, in this case
    • The formula will assume inches, so we added “Inches” to the name
  2. Add a formula to control the Variable Length parameter
    • In words, to calculate the Variable Length;
      • If the Offset is negative, subtract the absolute value of the Offset from the Base Dimension
      • If the Offset is zero or positive, add the value of the offset to the Base Dimension
    • In the formula, note the multiplication by 1”.  This is to convert the Offset (Number) parameter to a distance.


Daniel Fahmi said...

How do you create an offset parameter? Is it under Project Parameters? Which category do we use?

Chander said...

Brilliant !! You Guys Rock !!

Deyan Nenov said...

Like! Like like like :))