I currently use the Geometry Generator styling on a point layer to draw the intersection between protection buffers around tree points and another polygon (say a building footprint) using the following expression:
The style typically calls for a line from the tree point to some edge of the polygon to make it clear which tree is connected to which polygon.
Currently I can achieve this on these irregular polygons using
shortest_line(), which is useful (see blue lines in image below).
intersection() would be another option per another question of mine)
But I would also like to draw a line from the tree point to the furthest edge of the resultant polygon so I can slap a label on it and indicate what the protection buffer radius is (outside of the intersection with the building polygon). See black lines in image above.
Keeping in mind that
- The point will always be within the buffer polygon
- Intersections with the building polygon can be at any angle so I can't just draw a line at say 45° and take the intersection of that.
- The final angle of the longest line to the polygon doesn't matter much
Is there any way to achieve this using expressions and the Geometry Generator style? I have a feeling a custom Python function would be required; my understanding is that finding the longest linear distance from a point to a polygon boundary would require some kind of sweeping algorithm (?)