to work with detail bending at trees and blend-/dirtlayers in cryengine like this http://freesdk.crydev.net/display/SDKDOC3/Detail+Bending
Artyom Zuev commented
By the way, my favorite use of vertex colors is Blend Layer shader introduced in CE3: http://mycryengine.com/assets/html/video/tv02_content_b.swf
Extremely awesome stuff that allows you to get away from texture repetition on large surfaces. But, yeah, dreams.
Artyom Zuev commented
Unfortunately, this is not possible.
It's not a matter of few additions to PlayUp plugin. Vertex Painting is a very complex feature that requires proper support in the native file format (nonexistent in .skp) and a proper toolset to work with it, at least some basic vertex editing mode (nonexistent in SketchUp).
There is a good plugin that provides a way to work with separate vertices, with a variety of features: http://www.thomthom.net/software/vertex_tools/ Theoretically, it could have been used as a base for Vertex Painting plugin development (because extremely complicated development of vertex editing mode is already done there), if there wasn't a problem.
First of all, SketchUp file format does not support vertex colors, so plugin will have to store this data in a proprietary way somewhere else. You won't be able to see your work in any other SketchUp copy, as there won't be a plugin to read the information. Not that big of a deal, frankly. But here comes the good part.
Formats SketchUp is capable of exporting are not supporting vertex colors either. So, any work you can do on a plugin, no matter how good it is, is rendered pointless when you realize that vertex color information can't be crammed anywhere to be sent outside.
Except .fbx. This is the only file format that supports vertex colors, so theoretically, after enormous amount of work on the further development of Vertex Tools, after studying fbx documentation, after finding a way to cram additional information into the .fbx exporter routine... yeah, you can have vertex color information in your model. Now you get the chance to import your model into 3ds Max or Maya, congratulations!
Wait, 3ds Max or Maya already had every vertex tool imaginable and vertex color functionality long ago implemented. Uh-oh, now the whole work on SketchUp plugin solution is rendered pointless. You could have done all the vertex painting in this software. If you even have it (most indie developers don't, as, you know, nice price tags).
Not to mention that .fbx export is only available in SketchUp Pro, which is a commercial product itself, with 495$ price tag.
As about direct SketchUp -> Engine export with vertex color information, a way we're accustomed to with PlayUp: as I've mentioned, it's not possible, because .dae file format employed in the process can't store that information.
As much as I'd like to have vertex painting functionality and export in SketchUp, it's a subject better brought up before SketchUp developers, as it's practically impossible task for plugin developers.
TL;DR: Sounds awesome, can't be done.