Constant area polygons/rectangles

Group,
One of my skill customizations requires the use of constant area
polygons/rectangles in the layout
Is there a way to build one,
What i am looking for is the following,
1. Given the area and the layer build a rectangle onto the layout.
2. Once the constant area rectangle is layed out, when one of the
edges is stretched the other edge should shrink to maintain the
constant area of the polygon

Thanks,
Partha

 

Partha,

If your polygon is a rectangle, this operation is a "move".

If your polygon has more than 4 sides orthogonal, and if you are
stretching only one side which intersect the bBox, then it is easy
to identify the opposite side, which is the opposite bBox side
and make the looped snapgid streching with a loop stop on the
area criteria.
If the edges are not those intersecting the bBox, there are too many
cases, and you should consider many situations ...

If your polygon is a triangle, or has non-mahattan shapes, the work
seems to me complicated, but it could be done depending on several
situations ...

================
Kholdoun TORKI
http://cmp.imag.fr
===================

 

I missed the case of the rectangle for which you want the
opposite edge to be fixed.
It can be processed in the same way as the the orthogonal
polygons I described previously. The edges to be stretched
are the perpendicular edges and not the opposite one.

================
Kholdoun TORKI
http://cmp.imag.fr
===================

 

I don t really know,
but it looks like a job for the stretchable pcells , like defined in the
ROD user guide (cf. roduser.pdf)

 

Yup, that's how I'd do it. Have a simple pcell which has stretch handles on both
sides.

Something like:

pcDefinePCell(
list( ddGetObj("master") "myrect" "layout")
(
(w 3.0)
(l 3.0)
(layer "metal1")
)
let((rect)
rect=rodCreateRect(
?cvId pcCellView
?layer layer
?width w
?length l
?origin -w/2.0:-l/2.0
) ; rodCreateRect
foreach(handle '("rightEdge" "leftEdge")
rodAssignHandleToParameter(
?parameter "w"
?rodObj rect
?handleName handle
?stretchDir "X"
?displayName 'w
?updateIncrement 0.1
?userFunction 'abRectWidthChange
)
)
foreach(handle '("upperEdge" "lowerEdge")
rodAssignHandleToParameter(
?parameter "l"
?rodObj rect
?handleName handle
?stretchDir "Y"
?displayName 'l
?updateIncrement 0.1
?userFunction 'abRectLengthChange
)
)
) ; let
) ; pcDefinePCell

procedure(abRectWidthChange(data)
let((area newW)
area=data->rodObj->width*data->rodObj->length
newW=data->paramVal+data->increment
data->parameters->w=newW
data->parameters->l=area/newW
)
)


procedure(abRectLengthChange(data)
let((area newL)
area=data->rodObj->width*data->rodObj->length
newL=data->paramVal+data->increment
data->parameters->l=newL
data->parameters->w=area/newL
)
)

Note, this code doesn't do any gridding - and rounding errors could cause the
area to wander after a number of stretches, but it shows the idea.

Andrew.

 

Andrew,
Thankyou very much!

Partha