Ok, So I've begun building a script to generate alignments. It's certainly fine to generate the horizontal and vertical separately, then project them to generate the 3D.
I'm reasonably sure Sketcher is the most expedient way to set up either alignment, but there are problems with using it to create alignments.
The alignment macro I'm writing really only needs three key elements: lines, arcs and tangential constraint. More complex geometries I intend on building (2-center, 3-center, and spiral curves) are simply a specific combination of tangentially-constrained lines and arcs.
The following PDF link provides a simple point of reference as to what the basic geometric requirements for alignments:
http://www.globalsecurity.org/military/ ... 33/ch3.pdf
So my plan is really pretty simple. The user simply selects one of five possible geometry types (tangent, simple curve, 2-center, 3-center, spiral) and can either append it to the end of the alignment, or insert it at a selected point. The macro then adds the desired geometry and tangentially constrains it to the surrounding geometry. From there, the user adjusts the curve / tangent either by click / drag or by manually entering data into a dialog.
The problem is, when applying a tangent constraint to two points, the result causes both objects to move. I want to ensure that the preceding geometry does not move. There is a constraint which does that, but it puts dimensions on the screen which are entirely irrelevant for my purposes.
Any way to achieve a fixed constraint without having to use that? It may be that I'm just not well-schooled enough in Sketcher's constraint system - apologies if this is an obvious question...