Add length parameter to Rel and Lay procedures

[dannief]

For diagrams with a lot of elements, it would be helpful to have more control of the layout, by manipulating arrow lengths. See below

@startuml
!include <C4/C4_Context>

System(a, A)
System_Ext(b, B)
System_Ext(c, C)
System_Ext(d, D)
System_Ext(e, E)
System_Ext(f, F)
System_Ext(g, G)
System_Ext(h, H)
System_Ext(i, I)


Rel(a, b, " ")
Rel(a, c, " ")
Rel(a, d, " ")
Rel(a, e, " ")
Rel(a, f, " ")
Rel(a, g, " ")
Rel(a, h, " ")
Rel(a, i, " ")
@enduml

After increasing the arrow length for some relations, the following diagram can be achieved.

@startuml
!include <C4/C4_Context>

System(a, A)
System_Ext(b, B)
System_Ext(c, C)
System_Ext(d, D)
System_Ext(e, E)
System_Ext(f, F)
System_Ext(g, G)
System_Ext(h, H)
System_Ext(i, I)


a --> b
a ---> c
a --> d
a ---> e
a --> f
a ---> g
a --> h
a ---> i
@enduml

Using the nodesep skinparam, and longer arrows, the diagram can be further condensed.

@startuml
!include <C4/C4_Context>

skinparam nodesep 10

System(a, A)
System_Ext(b, B)
System_Ext(c, C)
System_Ext(d, D)
System_Ext(e, E)
System_Ext(f, F)
System_Ext(g, G)
System_Ext(h, H)
System_Ext(i, I)


a --> b
a ---> c
a ----> d
a --> e
a ---> f
a ----> g
a --> h
a ---> i
@enduml

[kirchsth]

Lay_Distance() support is part of #143. PlantUML has a limitation and "distance" only work in layout direction (details see #134) and therefore I cannot make a solution which works in all directions.

In the meantime you can use my branch like below
BR Helmut

@startuml
!include https://raw.githubusercontent.com/kirchsth/C4-PlantUML/extended/C4_Context.puml
' !include <C4/C4_Context>

skinparam nodesep 10

System(a, A)
System_Ext(b, B)
System_Ext(c, C)
System_Ext(d, D)
System_Ext(e, E)
System_Ext(f, F)
System_Ext(g, G)
System_Ext(h, H)
System_Ext(i, I)

Rel(a, b, " ")
Rel(a, c, " ")
Rel(a, d, " ")
Rel(a, e, " ")
Rel(a, f, " ")
Rel(a, g, " ")
Rel(a, h, " ")
Rel(a, i, " ")

' Lay_Distance(a,b,0)
Lay_Distance(a,c,1)
Lay_Distance(a,d,2)
' Lay_Distance(a,e,0)
Lay_Distance(a,f,1)
Lay_Distance(a,g,2)
' Lay_Distance(a,h,0)
Lay_Distance(a,i,1)
@enduml

[dannief]

Did not realize that Lay_Distance could be used with Rel like this. Lay_Distance was what I was looking for.

[kirchsth]

@Potherca: I wouldn't mark it with "wontfix" we have a working solution (workaround) for that