Hi Dan.

Yep

I hadn't thought of that case. Also missed the case
where the two rectanges share a width or a height and
overlap like playing cards on a solitare layout.

Back to the drawing board. Worthy problems prove their
worth by fighting back. :-)

Yours in curiosity and service, --Jerome Peace

--- Dan Ingalls <Dan at SqueakLand.org> wrote:

> Hi, Jerome -
> 
> Your code is interesting, but it did not seem to
> work for me in the 
> case of, eg...
> 
> AAAA
> ABBA
>   BB
> 
> But I haven't got anything better, either ;-).
> 
> 	- Dan
> ------------------------------------
> >Difference of Rectangles
> >
> >Hi JIm,
> >
> >The following is some workspace code (copy into a
> >workspace.
> >Select and do all of it. Then recolor and move the
> >rectangles around.
> >And select and do the last bit.
> >
> >note: #flipRotated:  is new as of 3.9. I don't know
> >how people got along without it.
> >
> >aLessB :=
> >[ :a :b | | overlap |
> >	overlap := a intersect: b .
> >	overlap area  = 0
> >		ifTrue: [ a corners ]
> >		ifFalse: [ overlap area < a area
> >					ifFalse: [ a corners ]
> >					ifTrue: [oCorners := overlap corners .
> >							verts := 
> >OrderedCollection new .
> >							a corners 
> >withIndexDo:  [  :each :eachIndex |
> > 
> >	((oCorners at: eachIndex) dist:  each) < 1
> > 
> >	ifTrue: [ verts
> > 
> >				addAll: ( oCorners
> > 
> >							flipRotated: 
> >eachIndex negated * 2  
> > 
> >								+ 1)
> > 
> >						allButLast ]
> > 
> >	ifFalse: [ verts add: each ]	] . verts ] ] ].
> >
> >
> >
> >aRect := RectangleMorph new openCenteredInWorld .
> >bRect := RectangleMorph new openCenteredInWorld .
> >poly := PolygonMorph new openCenteredInWorld .
> >
> >polyVerts :=
> >aLessB value: aRect bounds
> >	    value: bRect bounds .
> >poly setVertices: polyVerts; changed .
> >
> >I had done something similar for puzzle pieces. And
> I
> >had fun working this one out.
> >
> >Yours in curiosity and service, --Jerome Peace
> >
> >
> >
> >
> >>   Jim Rosenberg jr at amanue.com
> >>   Sun May 6 20:12:03 UTC 2007
> >
> >> 
> >>   Consider two rectangles, a and b. The only
> >constraint I
> >>   will put on them is
> >>   that neither contains the other. I wish to
> create a
> >>   PolygonMorph
> >>   programmatically consisting of a merge: b with
> b
> >>   removed but all of a
> >>   retained in the case a and b overlap. I think I
> see
> >my
> >>   way to how to do
> >>   this, but if anyone knows of any code I can
> look at
> >>   where something like
> >>   this is already implemented I'd be much
> obliged.
> >> 
> >>   My idea for how to go about this is to use
> "turtle
> >>   logic" more or less as
> >>   follows: Start with the first vertex of a
> merge: b
> >>   which is not inside of
> >>   b. Proceed clockwise along the bounds of a
> merge:
> >b; if
> >>   you hit b turn
> >>   left, if you hit a turn right. But this may be
> >doing
> >>   things the hard way.
> >> 
> >>   -Thanks, Jim
> >
> >
> >
> >
>
>____________________________________________________________________________________
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