LivePathEffects Discussion

Discussion page for Johan's Live Path Effects project for GSoC2007.

What's it look like in SVG?

Simple idea

    <path
       inkscape:original-d = "..." (the original path that now has an applied effect)
       d="..."  (the output of the live-effect)
       inkscape:path-effect="..." (string with the name of the applied effect)
       inkscape:path-effect-param1= ...   (can be anything)
       inkscape:path-effect-param2 , etc
    />

This is what is implemented at this moment.

• No chaining possible
• Difficult to determine path-effect-param type from SVG.
• not extendable (8 params max at the moment by copy-paste coding)

Like style atribute

<path
   inkscape:original-d = "..."
   d="..."
   inkscape:path-effect="sample1(param1:0.0;param2:loopy;) sample2(paramA:45;)"
/>

• Parser needed
• LPE class that stores its own params

<inkscape:patheffect>

<svg:path d="M 1 2 L 3 4">
  <inkscape:patheffect effect="org.inkscape.patheffect.a">
    <inkscape:param name="foo" type=".." value="bob" />
    <inkscape:param name="bar" type=".." value="jack" />
  </inkscape:patheffect>
  <inkscape:patheffect effect="org.inkscape.patheffect.b">
    <inkscape:param name="zort" type="bool" value="true" />
  </inkscape:patheffect>
  <inkscape:patheffect effect="org.inkscape.patheffect.a">
    <inkscape:param name="foo" type=".." value="alvin" />
    <inkscape:param name="bar" type=".." value="jack" />
  </inkscape:patheffect>
</svg:path>

defs section

<svg:svg>
...
<defs>
...
<inkscape:path-effect xlink:href="x-inkscape-plugin:org.inkscape.effect.foo"  id="path-effect2">
  <inkscape:param name="blah" type=".." value="foo" />
</inkscape:path-effect>
...
</defs>
...
<svg:path ... inkscape:path-effects="#path-effect2 ..." />
...
</svg:svg>

Looks alot like gradients.

• upside: you can apply the same effect (with equal params) to different objects very easily.
• downside: same as with gradients, might become a problem with parameters changing for only one object of all the objects referring to a certain effect, which then needs forking etc etc...

Effect Wishlist

• Skeletal Strokes
• Fillet & Chamfer
• Fractalize
• Interpolate
• Effect Lines (sorry about the japanese, but it should make visual sense - http://www.wa.commufa.jp/~ksg/p_pfwp5_cgf.htm )
• Mesh Distort (with variable mesh resolution) - Like gradient meshes but for distorting the object itself, not color