Ideas:
Use Bezier Curve.
There should be an end type where transparent bezier curves over lap nicely.
Search for regions where parallel lines can be drawn.
Space up to 5 lines next too each other. Leave then some extra space to see direction better.
Draw lines only nice when the user leaves enough space between elements.
Draw lines only in approximately the correct direction.
Start and end lines always pointing to the exact position of the connected element.
Optimize lines so, that not too much overlapping occurs.
Make sure that no lines cross in a way that it is not clear where a line goes to.
Make it possible to highlight a single line.
Make it possible to display start and end of a line.
For now the idea is that lines are always drawn automatically. Users can not correct lines. In case adaptions by users are made possible. Such adaptions have to be stored in some way to file.
Ideas: Use Bezier Curve. There should be an end type where transparent bezier curves over lap nicely. Search for regions where parallel lines can be drawn. Space up to 5 lines next too each other. Leave then some extra space to see direction better. Draw lines only nice when the user leaves enough space between elements. Draw lines only in approximately the correct direction. Start and end lines always pointing to the exact position of the connected element. Optimize lines so, that not too much overlapping occurs. Make sure that no lines cross in a way that it is not clear where a line goes to. Make it possible to highlight a single line. Make it possible to display start and end of a line.
For now the idea is that lines are always drawn automatically. Users can not correct lines. In case adaptions by users are made possible. Such adaptions have to be stored in some way to file.