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Closed Spline resizing

Question asked by 1-HH5PKI on Jun 17, 2009
Latest reply on Jun 18, 2009 by 1-HH5PKI
Ok, so I work in the eyewear industry as a designer for eyeglasses and sunglasses. I'm having trouble resizing a closed spline (in SWx) in the same manner that I do it in Adobe Illustrator.

So, our 2d workflow is based in Adobe Illustrator and I've grown accustomed to drawing eyeshapes (the shape of the lens) in AI. The eyeshape is always a spline (no lines, no arcs) drawn with the pen tool. Once we draw a shape we like, we size that spline to the proper size.

In the eyewear industry the side-to-side width of the eyeshape is called the 'A' dimension (or just the 'A') and the top-to-bottom height is referred to as the 'B' dimension (or just the 'B'). The A absolutely must be an integer. The B must be sized to the nearest 1/10th of a millimeter (i.e. it can be 35.7 or 35.8 but not 35.77) Pretty straight forward.

Ok, so once I have that shape, I can very easily go to the transform palette (and activate the chain link to proportionally scale the shape) and enter the A dimension for the lens. I'll check what that corresponding B dimension results and then turn off the chain link and type in a value that is rounded to nearest 1/10th of a millimeter. Boom, I'm finished. (this is what's illustrated in the attached AI and PDF)

How on earth do I replicate this in SWx? I was hoping that blocks could get me there, and while they get me closer than any other strategy (I only have two up to this point), it's still not quite right.

To illustrate verbally ... let's just say that I'm starting out in SWx from scratch and I will create the eyeshape there.

(1) I open a new sketch
(2) I draw a construction rectangle centered about the origin (using a diagonal centerline) that is roughly the dimensions I want the eyeshape to be, say 55mm (A dim) by 40mm (B dim)
(3) I draw any random eyeshape that "looks right" (again, very subjective) and for this purpose make it nearly tangent to the rectangle I've already drawn.
(4) I add 4 tangent constraints

Everything is usually ok at this point. But heaven forbid I to to try to proportionally scale that rectangle up to a 58mm ... You can forget it. I'm nearly guaranteed that SWx will spit out something UGLY or the spline will turn red or yellow and fail.

After trying this a few times, I realized that (duuuuuuuh) SWx is treating that spline differently than AI b/c AI treats is as an object when it comes to dimensions/size. Essentially it just scales everything that defines that closed spline according to the dimension I entered. SWx doesn't know that it needs to change all the magnitudes and angles on the handles ... it simple makes the rectangle bigger.

This is when I started looking into blocks b/c I was hoping to be able to edit at one "level", then sort of lock that level and change the size at a second level. This is conceptually how I think about how AI is doing things.

So, then I try to draw any random shape once again in a new sketch. I turn that closed spline into a block and then drop a construction rectangle on top of it and add the 4 tangent relations. I pull out dimensions (driven, of course) to evaluate it's size. I then have to use the block scale field to change the driven dimension. I keep nudging up or down the value until either the A is an integer or the B is a 1/10th of a millimeter. This works, but only for one of the dimensions. I want to be able to control both the A and the B.

I'm essentially at a loss and my only recourse is to work back and forth between AI and SWx, which is completely liveable, but I feel like there must be a better way to control a spline in SWx.