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Skipping on rendaring shape
I have simple question about skipping way on rendering shapes in KLayout.
In general, if target shape is less than half of 1-pixel, skipping of rendering shapes make draw faster.
What is the design policy of rendering skip in KLayout?
Regards,
-Kenji Morohashi-
In general, if target shape is less than half of 1-pixel, skipping of rendering shapes make draw faster.
What is the design policy of rendering skip in KLayout?
Regards,
-Kenji Morohashi-
Comments
Hi Kenji,
sorry for the late response, I simply missed your forum entry.
Regarding the rendering in KLayout: One basic design requirement was not to skip any shapes because that will change the appearance of a layer. Think of a layer consisting of small shapes only (i.e. a via layer): if one would simply skip those shapes the layer would completely disappear below a certain zoom level. In addition, the conservation of pixel information is the key feature when using the "marked" layer style to identify sparse layout shapes in a large void.
Instead, KLayout always tries to render at least a pixel if a shape is present. Since KLayout uses a custom rasterization engine, drawing of a pixel is simply setting one bit in the bitmap. This is a very fast operation and is even faster than the determination of the shape's extents in pixel units, so there is not much performance to gain by skipping that operation.
Instead, KLayout optimizes drawing by replacing a cell by a single pixel if the cell's extent drops below the 1.5x1.5 pixel size. For large zoom levels, that optimization applies already to standard cells, so this is a quite efficient optimization. Still it preserves the general appearance of a layer.
Best regards,
Matthias