Re: [svgwg] SVG marker orientation at a 180° U-turn not well defined

I am sure we are spending an unnecessary amount of time thinking about something no-one will ever notice, but...

May I suggest reorienting your arrow so it points along the X axis. I think it makes the directions more intuitive.

Also I think that for completeness, the test should also include right-to-left versions of the lines.  Ideally the angle of the marker should make sense given the overall direction of the line.

```
<svg xmlns="http://www.w3.org/2000/svg"
     viewBox="0 0 20 40"
     width="250" height="500">
  <marker id="m"
          overflow="visible"
          orient="auto">
    <polygon fill="red" fill-opacity="0.8"
             points="0,-1, 3,0, 0,1"/>
  </marker>
  <!-- ltr "M" shape -->
  <path fill="none" stroke="navy"
        d="M0,5 L2,4
           Q10,0 10,6
           Q10,0 18,4
           L19,8"
        marker-mid="url(#m)" />
  <!-- ltr "W" shape -->
  <path fill="none" stroke="seaGreen"
        d="M0,15 L2,16
           Q10,20 10,14
           Q10,20 18,16
           L19,12"
        marker-mid="url(#m)" />
  <!-- rtl "M" shape -->
  <path fill="none" stroke="navy"
        d="M20,25 L18,24
           Q10,20 10,26
           Q10,20 2,24
           L1,28"
        marker-mid="url(#m)" />
  <!-- rtl "W" shape -->
  <path fill="none" stroke="seaGreen"
        d="M20,35 L18,36
           Q10,40 10,34
           Q10,40 2,36
           L1,32"
        marker-mid="url(#m)" />
</svg>
```

Edge:

![markers_edge](https://user-images.githubusercontent.com/840288/28242164-0d324ac0-69f9-11e7-8829-9e797d104b73.png)

Firefox:

![markers_firefox](https://user-images.githubusercontent.com/840288/28242154-b7ea85f0-69f8-11e7-8938-cbccc7c3d0e5.png)

Chrome/Safari/Inkscape

![markers_chrome](https://user-images.githubusercontent.com/840288/28242156-bd1ef146-69f8-11e7-9bf2-d3b30545f551.png)

**Ideally the orientation would be as follows I think:**

![markers_ideal](https://user-images.githubusercontent.com/840288/28242208-ad463454-69f9-11e7-8edf-d18bf33fb9b1.png)


-- 
GitHub Notification of comment by BigBadaboom
Please view or discuss this issue at https://github.com/w3c/svgwg/issues/333#issuecomment-315559776 using your GitHub account

Received on Saturday, 15 July 2017 20:21:38 UTC