Now you see it, now you don’t (or, what condition my condition is in)

We all know you can control visibility in families using a conditional parameter. Let’s say you need two types of curtain panel. One includes a shading device (the ‘yes’ condition) the other, does not include a shading device (the ‘no’ condition). To manage this you simply create a yes/no parameter, call it Shading Device and link that to the visibility of the shade geometry.

But what if the presence of the shading device is not an either/or situation. What if you’d like it to be dependent on a variable condition? For example, you only want the device when the panel height is greater than a specified value.
To make this to work you’ll need to take advantage of Reporting Parameters.
Open a new curtain panel family and create geometry for the panel and a simple shading device at the top of the panel.
Create a new parameter and call it Minimum Panel Height. It should be a type parameter.
Create another parameter and call it Curtain Panel Height. This is your reporting parameter. It doesn’t control any geometry it just ‘reports’ a length or angle value that you can schedule or use as a variable in formulas.
Add a dimension that references the top and bottom reference planes of the curtain panel family and assign the Curtain Panel Height parameter. When you load the curtain panel into the project Revit will ‘report’ the height of the curtain panel to the family and the family will function based on what is reported.
The last step is to create your formula. The formula is assigned to the Shading Device parameter.
The formula uses a conditional statement instructing Revit to Report the curtain panel height and subtract it from the Minimum Panel Height. If the result is less than 0 (zero) then the visibility box is unchecked. If the result is more than 0 (zero), i.e. the panel meets the minimum height requirement, the visibility box is checked.
You can read the AUGI post that was the inspiration for this post and download the family inside a project here. Create a curtain wall using the panel and add a few horizontal grids of varying heights. Change the minimum panel height parameter and see how it affects the visibility of the shading device.
Reporting parameters can be used in all sorts of ways to inform your families how they need to react. Because they can be scheduled you can also use them to test for constructibility issues. In the curtain panel example shown here you could schedule the panel heights to make sure your panels don’t exceed a maximum fabrication of transportation length. Let the model inform the design process.
Dimitri Harvalias

About

Dimitri is a Senior Technical Consultant and Revit Guru at Summit Technologies. He draws on over 35 years of practical experience in the AEC domain. His education as a building technologist and hands-on experience in all facets of design, construction contract administration and CAD management gives him a unique perspective on the integration of BIM technology solutions to the design and project delivery process.

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