Paint Effects Vertex Color as User Data

It’s great to have such a tool like Maya’s Paint Effects.
A short and simple way to use the leaves color randomization feature as a texture modulation source:

  • Create your beautiful plant with Paint Effects. 🙂
  • Use the leaf color randomization feature – you can see it in the viewport.
    (brush node -> Tubes -> Growth -> Leaves)
    Screenshot 2018-06-05 22.02.26
  • Convert your plant to polygons with the usual settings:
    Vertex color mode: Color (this is necessary to get vertex color)
    Quad output: on
    Poly limit: 0 (means no limit)
    (Modify -> Convert Paint Effects to Polygons)
  • Select the leaf geometry and turn on the vertex color preview for that.
    (mesh node -> Mesh Component Display -> Display Colors)
    Screenshot 2018-06-05 22.03.46.png
  • You can change any attributes on the stroke or the brush node.
    For example change the leaf color randomization attributes.
  • Create a userDataColor node (Arnold: aiUserDataColor, Redshift: rsUserDataColor) Type in the name of the color set, the default is colorSet1.
  • Now you can use the userDataColor node to modulate/blend/mix texture colors
    via some kind of layered color node (Arnold: aiLayerRgba, Redshift: rsColorLayer)
    Screenshot 2018-06-05 22.17.36.png

Tip:

  • You can paint Vertex Color by hand and use that via a userDataColor node.
  • You can generate vertex color on any geometry for each polyShell. It’s useful to modulate color, roughness, UV offset, or any other attribute via vertex color.I created a very crude MEL script to do that (really ugly and slow).
    Here it is:

//Select an Object than run this script
{
float $r = rand(0.0,0.2);
float $g = rand(0.3,0.5);
float $b = rand(0.0,0.2);
polyColorPerVertex -r $r -g $g -b $b;
}
{
ConvertSelectionToFaces;
float $rRatio = rand(0.0005,0.1);
polySelectConstraint -m 3 -t 0x0008 -r 1 -rr $rRatio;
polyConvertToShell;
float $r = rand(0.0,0.2);
float $g = rand(0.3,0.5);
float $b = rand(0.0,0.2);
polyColorPerVertex -r $r -g $g -b $b;
polySelectConstraint -m 0 -t 0x0008 -r 0;
select -cl;
toggleSelMode;
toggleSelMode;
changeSelectMode -object;
}
{
ConvertSelectionToFaces;
float $rRatio = rand(0.0005,0.05);
polySelectConstraint -m 3 -t 0x0008 -r 1 -rr $rRatio;
polyConvertToShell;
float $r = rand(0.0,0.2);
float $g = rand(0.3,0.5);
float $b = rand(0.0,0.2);
polyColorPerVertex -r $r -g $g -b $b;
polySelectConstraint -m 0 -t 0x0008 -r 0;
select -cl;
toggleSelMode;
toggleSelMode;
changeSelectMode -object;
}

Please don’t be shy. Tell me If you have a great python script for vertex color randomization for each polyShell in Maya.

Cheers, D

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