[Qgis-user] geometry generator - unexpected results
Michel Stuyts
michel.stuyts at edegem.be
Fri Apr 17 02:50:35 PDT 2020
The numbers you need to use in “rand(-10, 10), rand(-10, 10)” depend on the CRS of your layer. I tested it with some demo data in EPSG:31370 and I got a similar result as you. When I changed those numbers I got a better result. After you changed those, you can play around with that 100 inside the generate_series, to get the result you want. For me the following gave a good result:
make_line(
array_foreach(
generate_series(
0, length($geometry), 300
),
translate(
line_interpolate_point($geometry, @element),
rand(-0.5, 0.5),
rand(-0.5, 0.5)
)
)
)
Michel
Van: Qgis-user <qgis-user-bounces at lists.osgeo.org> Namens David Fawcett
Verzonden: donderdag 16 april 2020 20:01
Aan: qgis-user <qgis-user at lists.osgeo.org>
Onderwerp: [Qgis-user] geometry generator - unexpected results
I am trying to use a geometry generator to accomplish the "hand-drawn" line style.
Some great recent examples by:
Klas Karlsson
https://twitter.com/klaskarlsson/status/1249333750451879937
Hamish:
https://polemic.nz/2019/11/18/foss4g-qgis-geometry-generators/
I am using the code below from the blog post by Hamish in QGIS 3.12:
make_line(
array_foreach(
generate_series(
0, length($geometry), 100
),
translate(
line_interpolate_point($geometry, @element),
rand(-10, 10),
rand(-10, 10)
)
)
)
Here is an image of what the results look like: https://github.com/fawcett/examples/blob/master/lines.png
The line geometries are in blue, and the geometry generator output is in black.
Can anyone suggest what is going wrong?
Thank you,
David.
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