Coordinate Dimensions for Base Sketch  4 sided part
Brian Enright Oct 2, 2018 7:59 AMGreetings,
I am working to develop an assembly of a (4 sided) window that will be scalable/configurable for size & shape. The intent is to control the variables with either a design table or global variables (which I am relatively comfortable with).
So, I am starting with a sketch of a quadrilateral to determine the overall size/shape of the part, and have the following constants set up:
 The lower left point (Corner1:C1) is fixed to the origin (0,0).
 The bottom line/side is horizontal.
(These rules simplify the design input from customers/sales.)
This leaves me with (5) values to control to determine the shape of my quadrilateral:
 Upper left (C2) point (x,y)
 Upper right (C3)point (x,y)
 Lower right (C4) point (x ) (lower line is horizontal, so no y value is needed)
The only one of these giving me problems is the Upper left x value (C2x) because it can be positive (right of x=0) or negative (left of x=0).
As my research into this dilemma has shown, SW doesn't like to maintain negative dimensions and so far my results have been:
Design tables: SW overrides all negative values in design tables to positive values.
Global variables: When confronted with a negative value SW constantly flips the sign convention upon rebuild & moves the point to either side of xaxis.
If there is anyone who has found a way to avoid these undesirable results please let me know. I'm attaching a ('17) part file that I've been trying this out on, and any help would be greatly appreciated. Also, uploading a quick video showing the results with global variables method.
Sidenote:
I've found macros to give the (x,y) coordinates of all reference points on a selected sketch (which does display negative values appropriately!) but I need to do the opposite and drive the corner points of a sketch from a series of ordered pairs.
Thanks for any help/assistance!

GlobalVariablesSketch.SLDPRT.zip 34.3 KB

Global Variables Result.avi 3.1 MB