overlapping polygon checking command in encounter

This is a common area of complexity so I'm glad you raised the question...

I don't think there are native commands to check for overlaps between polygons.  When I've done this in the past, I've always needed to decompose the polygons to boxes and then check for overlaps.

Depending on the version of Encounter you're using and the object type you're querying, there are a couple of ways you might decompose the power domain polygons (which I believe are considered placement constraints, or you could traverse from a power domain to its associated placement constraint) to rectangles:

• dbForEachConstraintBox might be helpful.  There is an example of using this command to decompose a rectilinear partition in the gifts directory in a script called "userBlockageUtils.tcl"
• If you're using 8.1, dbGet would expose the boxes directly off the constraint:
  encounter 7> dbGet selected.bndry.boxes
  {{894.3 733.6 1057.98 773.92} {894.3 542.08 1122 733.6}}

More info on getting started with dbGet can be found in this post in the Digital Implementation Blogs.

Let us know whether this points you in the right direction or if a more complete example would be helpful.

Thanks!
Bob

Hi Vicky,

Sorry for the delayed response on this one.  It slipped through the cracks, but in case you or anyone else is interested in a solution to this question, here is a way to get the boxes for a rectilinear power domain and check which instances in the design are within that rectilinear box:

set pd [dbGetPowerDomainByName PDpll]
set group [dbPowerDomainGroup $pd]
dbForEachGroupBoxListBox $group box {
  set boxPtr [dbBoxPtrBox $box]
  dbForEachCellInst [dbHeadTopCell] inst {
    set instBox [dbInstBox $inst]
    if {[dbIsBoxOverlappingBox $boxPtr $instBox]} {
      Puts "inst: [dbInstName $inst] is overlapping"
    }
  }
}

I was going to show a dbGet-style implementation of similar, but I found a couple of limitations in the dbGet schema which limit it from being useful in this case.  I'll work with our developers on a making this easier with a couple of enhancements.  For now, I hope this example is helpful.

Thanks,
Bob