Inconsistent Behaviour of Setback Operation

Question

I am perplexed as to why the Setback operation behaves differently in these two instances.  Can anyone shed any light?  My desired result is the one on the left.

Here's the rule that I am applying to the initial shape:

Lot-->

setback(2) {0:Yard | remainder:Building}

Yard -->

color("#7FA18A")

Building -->

extrude(12)

Please help.
Thanks! Geoff.

GeoffAbma · Answer

Thanks everyone for your help.  I have used the split function in conjunction with the alignScopetoGeometry to achieve what I wanted.

//--- Corner Lot (Right) ---//

frontYardcr -->
alignScopeToGeometry(yUp, largest, 0)
split(z) {~1: rearYardcr | frontSetback: colorGreen}

rearYardcr -->
alignScopeToGeometry(yUp, largest, 2)
split(z) { ~1: sideYard1cr | rearSetback: colorGreen}

sideYard1cr -->
alignScopeToGeometry(yUp, largest, 3)
split(z) { ~1: sideYard2cr | flankageSetback: colorGreen}

sideYard2cr -->
alignScopeToGeometry(yUp, largest, 1)
split(z) { ~1: buildableArea | interiorSetback: colorGreen}

BenLeslie1 · Answer

I don't think it's a bug - this is the behaviour I expect.

As you suggest, split looks like the correct tool for this job.

DavidWasserman · Answer

I see, at first I thought it might have to do with Edge indexing, but a small difference in angle seems hard to perceive just from the image. My first comment was unhelpful. For a rule to generalize, I guess you could use geometry.edges/is rectangular to determine if you should use setback vs. a well oriented split. It does seem very strange.

Does the behavior change if you use a different selector rather than the default?