Making skins work more than once in TGEA 1.8.1

While experimenting with TGEA 1.8.1, I found that setSkinName, while it did change whole materials, not just textures, would only work one time. I found this was a known issue and in this thread...

http://www.garagegames.com/community/forums/viewthread/74084

...I got pointed in the direction of the right code to look at. I came up with a generalized solution that worked fairly well for me, and posted it there. Recently, I got some feedback (thanks Andrew) that it is more straightforward than some other public solutions that have been proposed, so basically, this is just a reformat of those instructions as a public resource to make it a little easier to find for anyone who might still need it.

Step A:
In tsShapeInstance.h, find the definition for the TSShapeInstance class, and near the beginning add a new private member variable

// Add me just before the first "public:" in the 
// class definition for TSShapeInstance...
private:
     StringTableEntry mSkinName;

Step B:
In tsShapeInstance.cpp, find the method TSShapeInstance::buildInstanceData (there are multiple constructors, but they both call this method). Near the end of this method, add an initialization for our new member as follows...

mSkinName = StringTable->insert("base", false);

Step C:
Also in tsShapeInstance.cpp, find the method TSShapeInstance::reSkin. There are several simple, but key changes for this method...

1.) Near the very top, find the line which reads

const char* defaultBaseName = "base";

... and get rid of it. We're going to be substituting our new member variable for all instances of this variable, so it's now obsolete. Substituting a StringTableEntry works, because StringTableEntry is typed as a const char * anyway, and has the incidental side benefit that string storage space is minimized for multiple instances of this TSShapeInstance which wear the same skin.
So, of course, our next changes involve getting rid of references to that old variable.

2.) Scroll down a bit, and look for the lines

else
    newBaseName = String(defaultBaseName);

And replace it with...

else
    newBaseName = String(mSkinName);

3.) Scroll down a bit further this time, and find the lines that read...

bool replacedRoot = makeSkinPath(pathName, NAME_BUFFER_LENGTH,
                                 resourcePath, pName, defaultBaseName, 
                                 newBaseName);

Replace this with...

bool replacedRoot = makeSkinPath(pathName, NAME_BUFFER_LENGTH, 
                                 resourcePath, pName, mSkinName, 
                                 newBaseName);

Step D:
Lastly, we need to set the mSkinName member with the name of the new base for next time.

Be careful where you put this line! Make sure you insert it at the VERY END OF THE METHOD, OUTSIDE THE FOR LOOP. If you put it anywhere inside the for loop, you create an unfortunate bug where if the object has multiple materials to be skinned only the first one actually changes.

So, at the very end of the method, add...

mSkinName = StringTable->insert(newBaseName,false);

Now, when the first call to reSkin is made, mSkinName contains "base" (from the constructor), which is appropriate, since all textures to be skinned should start out this way. Each time a re-skin is performed, mSkinName is set to the last thing we changed to, so it keeps working no matter how many re-skins you do.