Display question: right angles

[Jmuccigr]

Lots of flow charts (and other similar things) use lines that run only at right angles, up and down, and left and right, like this:

mermaid instead produces lots of lines that run at angles. Any way to get the former rather than the latter?

[AlanHohn]

It appears from the dagre-d3 and d3 documentation that this would be possible if we could pass through the "lineInterpolate" argument to setEdge:

http://cpettitt.github.io/project/dagre-d3/latest/demo/style-attrs.html
https://github.com/mbostock/d3/wiki/SVG-Shapes#line_interpolate

I've been thinking about how to specify this and would like to contribute a PR. I'd appreciate some advice about the best way to integrate this into the flowchart language. There's an existing "linkStyle" construct that could be leveraged if it's done in a way that's backwards-compatible.

I was thinking:

linkStyle 3 interpolate stepBefore stroke:#ff3,stroke-width:4px;

Where the "interpolate stepBefore" would be optional in the grammar.

But that feels a little ugly to me, so another approach would be:

linkInterpolate 3 stepBefore

Which would be a little less compact but could be clearer.

[Jmuccigr]

@AlanHohn, What's ugly?

[AlanHohn]

I was thinking it was a little ugly because there's no explicit "style" keyword before the style section (to preserve backwards compatibility). But I imagine I'm being oversensitive.

I'll work it using the first approach.

[Jmuccigr]

Ah, that hadn't occurred to me and I think I lack the knowledge to have an informed opinion. :-)

[knsv]

@AlanHohn Sounds great! Looking forward to you pull request!