Sorry, I searched thru the help system with keywords like "color vertex". It gave me back a massive/enormous amount of info back just for changing the color of a vertex. Does anyone know any handy way to change the color of the vertex on the fly? Thanks Jack

You'll be wanting to write a modifier i'm guessing (you could use a utility if it's a click once - change colour type tool). You need to look for the Map's on the Mesh and MNMesh data structures - though be warned these are shared between UV sets and colour sets - so make sure you check the type. The Max plugin wizard should be able to create a bare-bones modifier for you, then it should be a case of filling in the blanks.

Unfortunately Max is not a particularly nice API imho. You may find the odd occasion where you have to randomly call Mesh::InvalidateVertexCache(), and other funcs like INode::InvalidateTM() to force Max to update itself properly. I'd recommend hunting down a free E-book written by david lanier which has a pretty good intro into the SDK(and may give you all the info you need IIRC). He's also got a pretty good max SDK forum on his website as well...

In addition, checking the SDK docs for the TVFace, MeshMap, and Mesh classes is probably a good idea....