How to correct PlantUML Line Path

Question

I created this diagram using the following code. But as you can see, the lines going from (Cancel Order) and (Place Order) to (Publisher) decide to take a terribly rounded path to get their, instead of going straight to the right and then down to publisher. I tried using manual direction commands like "-down" but none of them seemed to help. Does anybody know how to fix this?

And here is my code. I appreciate any help. Thank you.

@startUML EBook Use Case Diagram left to right direction Actor Customer as customer Actor EBook as ebook Actor Publisher as publisher rectangle "Book Catalogue" {     together {         Actor "Book Database" as bookLog         (Retrieve Information) as getBook         customer -- getBook         getBook -- ebook         getBook -- bookLog          (Update Catalogue) as updateCatalogue         ebook -- updateCatalogue         updateCatalogue -- bookLog     }      together {         (Place Order) as order         customer -- order         order -- ebook         order--publisher          (Cancel Order) as cancelOrder         customer -- cancelOrder         cancelOrder -- ebook         cancelOrder--publisher     } }  (Ship To EBook) as shipEBook shipEBook -- publisher (Ship To Customer) as shipCustomer customer -- shipCustomer ebook -- shipEBook shipCustomer -- ebook  (Return to EBook) as returnCustomer (Returnto Publisher) as returnPublisher customer -- returnCustomer returnCustomer -- ebook ebook -- returnPublisher returnPublisher -- publisher  @endUML 

Answer 1

Try the options suggested by @Peter Uhnak along with linetype :

skinparam linetype polyline skinparam linetype ortho 

Give better options for lines. Using ortho - (Here)

you will get -

Answer 2

There are some tricks that you can try, listed below. The layouting itself is performed by GraphViz (dot layouting iirc), and GraphViz simply does this sometimes. Graph layouting is a NP-complete problem, so algorithms usually take harsh shortcuts.

Typical workarounds that I've seen or used include:

• adding hidden lines a -[hidden]- b
• extending the length of a line a --- b (more dashes, longer line)
• specifying preferred direction of lines (a -left- b)
• swapping association ends (a -- b → b -- a)
• changing the order of definitions (the order does matter... sometimes)
• adding empty nodes with background/border colors set to Transparent

So if you really want to have a nice layout, you'll need to put some elbow grease in, but keep in mind that the layout will be still brittle -- if you add/remove items, you might need to redo it again.