DRC Function Internals
This document describes some of the DRC functions in detail, specifically with respect to deep mode and pre-merge behavior.
DRC Function Details
In the table below A is for the first operand in binary operators of self for methods. B is for the second operand or the first method argument. For example:
# A is self result = A.interacting(B) # A is first operand in binary operators result = A - B
Further columns include:
- Type: layers can be polygon, edge, edge pair or text layers. Depending on the type, operations can behave differently.
- Pre-merge: some operations mandate pre-merging. Pre-merging means, that
clusters of shapes are combined into larger polygons and internal edges are removed.
After pre-merge, polygons to not touch or overlap. Pre-merged polygons are
placed in the hierarchy on the first level where these polygons are complete.
Pre-merging therefore often accounts for hierarchy degradation. Pre-merging
can add a considerable performance overhead.
For edge layers, pre-merging is also applied. In that case, collinear edges are combined into single ones.
Pre-merging is not applied to layers that are merged already, specifically layers that a the result of an operation that delivers merged layers. Pre-merging is also referred to as "merged semantics" and can be suppressed by using "raw" mode (merged semantics off). - Primary input: the primary input of an operation determines the hierarchy level on which the results are evaluated. Less shapes on the primary layer mean less work for the CPU. It can be beneficial to use the more hierarchical layer for the primary input as this means that evaluation will happen deeper inside the hierarchy and therefore potentially with a better hierarchy utilization.
- Range: some operations have an interaction range - that is the distance by which the function needs to search for neighbor shapes it has to include. Longer interaction ranges mean more search effort and potentially higher complexity. For a uniform shape density complexity increases with the square of the range.
Please see the comment column for further details.
| Function | Type | Pre-merge | Result merged | Range | Primary input | Comment |
|---|---|---|---|---|---|---|
| with_* and without_* | polygon or edge | yes | yes | |||
| Polygon predicates (rectangles, squares, rectilinear and related non_* methods) | polygon | yes | yes | |||
| holes and hulls | polygon | yes | no | |||
| end_segments, start_segments and centers | edge | yes | no | |||
| extended, extended_in and extended_out | edge | yes | no | |||
| edges | polygon | yes | yes | |||
| first_edges and second_edges | edge pair | n/a | n/a | |||
| bbox | any | no | no | |||
| area, perimeter, is_box? and length | polygon | yes | n/a | |||
| flatten | any | no | no | |||
| select, each and collect* | polygon or edge | yes | yes | |||
| rounded_corners | polygon | yes | yes | |||
| smoothed | polygon | yes | yes | |||
| corners | polygon | yes | yes | |||
| middle | polygon | yes | yes | |||
| extent_refs | polygon | yes | yes | |||
| ongrid | polygon | yes | no | Reverts to flat mode for anisotropic grids. | ||
| odd_polygons | polygon | no | no | |||
| snap and snapped | polygon | yes | no | Creates cell variants. Reverts to flat mode for anisotropic grids. | ||
| and and not (& and - operators) | polygon and edge | no | no | 0 | A | |
| andnot | polygon and edge | no | no | 0 | A | |
| xor (^ operator) | polygon and edge | no | no | 0 | both | Basically implemented as (A-B)+(B-A). |
| or (| operator) | polygon and edge | no | yes | 0 | both | Basically implemented as (A+B).merged. |
| join (+ operator) | polygon and edge | no | no | 0 | both | Cheap operation. Performs hierarchy mapping of B to A in case both inputs come from different hierarchies. |
| covering and related (not_covering, split_covering, select_covering, select_not_covering) | polygon | yes (A, B if counting) | yes | 0 | A | |
| overlapping and related (not_overlapping, split_overlapping, select_overlapping, select_not_overlapping) | polygon | yes (A, B if counting) | yes | 0 | A | |
| interacting and related (not_interacting, split_interacting, select_interacting, select_not_interacting) | polygon and edge | yes (A, B if counting) | yes | 0 | A | |
| pull_interacting | polygon, edge and text | yes (B) | yes | 0 | A | Can be used to re-hierarchise B along hierarchy of A (put B into raw mode to disable merging). |
| pull_overlapping | polygon | yes (B) | yes | 0 | A | Can be used to re-hierarchise B along hierarchy of A (put B into raw mode to disable merging). |
| pull_inside | polygon | yes (A, B) | yes | 0 | A | |
| inside and related (not_inside, split_inside, select_inside, select_not_inside) | polygon and edge | yes (A) | yes | 0 | A | |
| in and related (not_in, in_and_out) | polygon and edge | yes (A, B) | yes | 0 | A | |
| intersections | edge | no | no | 0 | A | |
| inside_part, outside_part and inside_outside_part | edge (A), polygon (B) | no | no | 0 | A | |
| width | polygon | yes | n/a | 0 | Single polygon check, no neighbors needed. | |
| space | polygon | no/yes | n/a | check value | Pre-merge is needed for: whole edges, rectangle filters, opposite filters and projection filters. | |
| notch and isolated | polygon | yes | n/a | check value | ||
| separation, overlap, enclosing and enclosed | polygon | no/yes | n/a | check value | A | Pre-merge of A is needed for: whole edges, rectangle filters, opposite filters and projection filters. Pre-merge of B is needed for: whole edges. |
| width and space | edge | yes | n/a | check value | ||
| separation, overlap, enclosing and enclosed | edge | yes (A) | n/a | check value | A | |
| with_density and without_density | polygon | yes | n/a | Runs in tiled mode always. | ||
| sized and size | polygon | yes | no | sizing value | Cell variants are generated with anisotropic sizing. | |
| extents | polygon or edge | yes | no | 0 | ||
| scaled and scale | any | no | no | Reverts to flat mode. | ||
| rotated and rotate | any | no | no | Reverts to flat mode. | ||
| transformed and transform | any | no | no | Reverts to flat mode. | ||
| moved and move | any | no | no | Cell variants are generated. | ||
| merged and merge | polygon or edge | yes | yes | 0 | ||
| select_props, map_props and remove_props | polygon | no | no | |||
| nets | polygon | no | no | |||
| fill | polygon | yes | n/a | Reverts to flat mode. | ||
| drc | polygon | depending on operation | depending on operation | depending on operation | A |
Edge Orientation and Edge-based Checks
By convention, edges are always oriented with "inside" being on the "right" side of the edge:
DRC checks ("width", "space" etc.) are available both for polygon and edge layers. Edges do not have a connection to a polygon and each edge is an individual objects, so the relation to other edges is purely defined by the orientation of the edge. The following pictures show these relations:
