Arnold 6.0.2 includes a new string_replace that lets you do find and replace on string parameters.
For example, I got an ass procedural file from a user, but I didn’t get the textures. Normally I would just enable ignore textures, but this time I used string_replace to replace all textures with my trusty-old-Softimage noicon pic.
Selection selects all Arnold image nodes. So this string replace operation applies to all string parameters of the image node (which includes name, uvset, color_space as well as filename).
Match is a regular expression that matches anything that looks like C:/project/sourceimages/example.tx or X:/temp/test/example.tx
[A-Z] matches any drive letter from A to Z
.* matches any string of characters
Note that match is a regular expression, so you cannot use glob wildcards like this: C:\sourceimages\*.tx (because * is not any string of characters, it is zero or more occurrences of the previous character)
\.tx matches a period followed by “tx”. The period has to be escaped with a backslash because ‘.’ matches any single character
Note that this match expression won’t handle something like example.txtra.tx
Replace is the string that replaces anything matched by the Match expression.
You can use the wireframe shader to drive the opacity of a standard_surface.
The wireframe shader itself doesn’t support opacity, and neither do the flat, utility, and ambient_occlusion shaders. They are all color shaders (RGB). In Arnold, only shaders that return closures can support opacity.
In the more general case, where the opacity isn’t coming from the same shader, you can use the emission for the color: