Andreas,Thanks for getting back, I have looked at similar ways to those outlined by your good self, the only issue being, they all require the creation of additional data or fields.
I will keep tipping away at it, once again, thanks for your help! Regards,
Richard. On 23/07/2015 10:01, Neumann, Andreas wrote:
Hi Richard,It would be interesting to have this as a built-in feature of the "line pattern fill" renderer in QGIS: being able to specify an angle relative to the longest line segment of a polygon.I have the same issue for our black and white base map - see http://webgis.uster.ch/wsgi/webgisLauncher.wsgi?uuid=a6634a18-d37f-4997-b3d8-d4c3aed51716There we would like the line pattern fill angle to be 30 or 45 degrees relative to the longest side of a building. Currently all of these hatch-pattern fills are manually rotated ;-(Meanwhile - until such a feature is available in QGIS - you could preprocess your data with a Python script be decomposing your polygon data to individual line segments, find the longest ones and get their angles. I would probably save this in a data-column to speed up rendering. But you said you can't do this - so maybe you really have to calculate this on the fly.For data in Postgis one could write a plsql function to calculate these angles.Sorry that I can't be of better help here. Just showing that I also have in interest in such a feature.Andreas On 2015-07-23 10:10, Richard McDonnell wrote:Hi,I am in need of some guidance, I am trying to create an "active hatch/Fill" as part of a style im working on. What I want is for a hatch to rotate depending on the orientation of a Polygon.For example, here is the same entity rotated, with the hatch rotating.The issue is I am working on a database, onto which I cant add any data (additional columns) to the tables, I would like to do this from within the styling. You can use an expression to denote the angle, so I was hoping to do it that way. I was looking to utilize the geometry of a bounding box, and calculate the angle of the diagonal, using something like180*atan((ymax - ymin)/(xmax - xmin))/$pi + 90But I am not having any luck....If there is no way at present to do this, Might I put it forward as a possible new feature?Regards, Richard. OPW - Ag féachaint don am atá le teacht - Ag caomhnú ón am atá thart OPW - Looking to the future - Caring for the past <http://www.opw.ie/> Email Disclaimer: http://www.opw.ie/en/disclaimer/ _______________________________________________ Qgis-user mailing list [email protected] <mailto:[email protected]> http://lists.osgeo.org/mailman/listinfo/qgis-user
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