I have been reading and watching and experimenting. I have Blender, so therefore can import 3ds, lwo, collada and a couple other object types.
I have a couple of paint programs capable of saving to alpha.
I tried to use the method Masonspappy described in Blender with duplicating the leaf mesh and then random select more or less from the duplicated mesh and apply a new snow texture. (I will find a way to get just the outer branches, I will, I will, ha!) This went pretty good, but I wanted to make the snow clumpy, so I added a solidify modifier to it and thickened it just a bit. I am now trying to see if I can apply the snow texture mask to the new snow here in TG. My questions are many, but mostly what file type does TG prefer and does it always need the opacity mask?
Below are my color and opacity images, originally 512x512, shown here just as examples. I would of course use a white image for the snow, it is just not shown here.
You cannot extrapolate the single leaf mesh from Blender original tree maker as far as I can tell or I would try that too.
