That is how I have learned to do this. We just use centerlines of each piece and represent a corner of the roof in plan view. From there with the rise, angle of plates, spacing, backing cut, and hip offset one can calculate everything. By laying certain triangles down in plan view and knowing which points to connect the angles can be found. If you are very precise with this you can then use a bevel to transfer the angles on the plywood or paper to the timber for lay-out, probably some of the most challenging geometry I have attempted, but once it clicks it clicks.
mymymy...
Ya, this is the way I figured it out, when I finally did. And I'm sure that next time it comes up, I'll have to re-figure it out again.
I find it quite difficult to wrap my brain around something on the written page, but in the shop with the plans and the timbers in front of me, well that's a whole different scene!
And somehow, I found the valleys easier to work with than the hips....either way, both are a great challenge!
And yes, they gotta have housings or something...don't just be lagging those jacks!
Good luck, buddy