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Vertexmapmerger and polygonselection merger
Vertexmaps can be used for lots of effects such as transparency, faking ambient lights and so on.
Polygonselections are normaly used to assign different textures to the polygons. When two objects are merged, the polygonselections are not merged. This plugin can merge multiple selectiontags with the same name into a single selectiontag.
If multiple polygon objects are merged in C4D, the vertexmaps won't be merged. This little tool can merge multiple vertexmaps in various ways, the most useful option might be the maximummerge that will merge two distinct vertexmaps correctly into one:
Two distinct objects with two vertex maps
The merged model - with two distinct vertexmaps
The merged vertex map
The plugin supports also other merge operations for each two vertexmaps: