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Subtracting two ellipses
Hi,
I am not able to subtract two ellipses in the same layer. Boolean functions in the menu (Add, Merge, Erase, Mask and Diff) operate well with Box shapes but not with ellipse shapes, why does it happens? How I can to perform a Diff or Erase operations between two ellipses?? (I create the ellipses by creating a box and then edit/selection/convert to PCell)
Thank you
I am not able to subtract two ellipses in the same layer. Boolean functions in the menu (Add, Merge, Erase, Mask and Diff) operate well with Box shapes but not with ellipse shapes, why does it happens? How I can to perform a Diff or Erase operations between two ellipses?? (I create the ellipses by creating a box and then edit/selection/convert to PCell)
Thank you
Comments
Hi,
ellipses are not shapes, they are PCell's. That is why they don't participate in boolean operations.
Let me explain: the basic format of KLayout is GDS which does not offer ellipses. One way to provide ellipses is by creating "ellipse-like" polygons, but drawing these is tedious.
Hence, ellipses are provide through another mechanism: special cells which are basically subunits of the layout and provide their layout through an algorithm which computes the contour based on parameters. Internally they maintain a contour but from the outside view they provide a few parameters which control the geometrical shape. Hence "parametrized cell" or "PCell."
The problem is simply that PCell's are not "normal" layout, but a special one which is dynamically connected to the algorithm. In order to make them participate in a boolean operation you will need to convert this layout into plain polygons. The easiest way to do so is to flatten the instances of the PCell's (select them and choose "Edit/Selection/Flatten instances"). After that, you'll have polygons which participate in the boolean operations in the usual way.
Matthias
First of all, thank you for your help. Which would be the steps to performance a boolean operation with two ellipses, for examplo yhe substraction or differencen between them? because, with box shapes first you must drow the first box and before you dran the second one, you must select the background combination mode tool button in the tool bar...but with PCells you can not to follow this steps because you must convert to PCell and flatten instances after drawing it....
thank you very much and sorry for the inconvenience
Hi,
instead of the background combination mode you can use "Edit/Selection/Subtraction": select the first shape from which you want to subtract. Then with Shift pressed you select the one to subtract. Then you choose "Edit/Selection/Subtraction".
Matthias
Thank you very much! I have already been able to substracting the ellipses.
Best
Ana