How to constrain the hip rafter frame to the slope of a Roof?

[Caed9]

Hi, could you please give some advice or feedback regarding roof structures? 

I'm currently trying to create a hip roof structure. I'm having issues when placing the hip rafter,  I created it by picking the line of the hip on the roof. 

But let's say that I want to change the slope of the roof, is there a way to constrain the hip rafter beam to follow the slope of the roof in case I edit the roof slope to a different angle. Is it possible? or what best practice do you recommend me for this kind of scenario. 

I uploaded a sample file and a video where I try to create the framing.

Thanks in Advance I appreciate your advice!

[Caed9]

 Here is a preview image, I changed the roof slope but the hip rafters stayed with the same slope. Or the same end and start elevations. 

[jbrazier · Accepted solution]

I don't know of any way to constrain a framing member itself to the slope of a roof (besides involving Reference Planes) but you can use the same approach as sloping a beam & column roof.  Since you can attach a column to the underside of a roof or floor and you can attach a beam to a column by changing the Start/End Attachment Type from End Elevation to Distance the top of column will always follow the roof slope dragging the beam with it.  I place columns where necessary and put them on a future phase specifically for these columns so they are not visible in the current phase but the attachments remain.  This also works best if you start with framing that's flat, with no vertical offsets  Keep in mind the Start/End Attachment Type parameter only exists on beam ends that are connected to columns making it difficult to globally change it.  I have created a Dynamo script to take care of this.

It may sound cumbersome but it's actually not and works quite well and those columns can be deleted after the final slope is determined.

[Caed9]

@jbrazier Many thanks for your advice, I was also thinking of creating a truss only with an extendable top cord and maybe a bottom cord for some additional support, as the design calls for a vaulted ceiling. But I noticed that the attachment is not on a plane, but on the hip rafter Line, so the top cord is intersecting the roof on the corners of the beam section. I just wonder if it is possible to create a parametric offset to the top cord, on the family editor. But temporary columns sounds like a quick solution I appreciate your advice. Maybe I can integrate the column on the roof structure. 

Look at the image below I attached the truss to the hip rafter line but it seems that the roof intersects the top corners of the beam section. I would like to edit it for more precision.