I was reading around the internet on how to render a tree using billboarding style in directx by using a 3d Mesh exported to .X file format and got me confused on one single item.
I have learned that the mesh will be divided into 2 parts, one 3d mesh for the trunk and branches, and a number of transparent billboards (quads) of leafs.
now my question,
On the modeler side,
how would the artist model a tree in 3DS max that supports transparent Billboarding and export the mesh in .X format?
As for the format type, it depends on what your game engine's importer supports. Natively, DX 10 and lower versions support the X file format. However, DX11+ doesn't. There are 3rd party plug-ins for 3DS Max that will allow you to export in the X file format.
When modeling vegetation most large studios use SpeedTree. It's expensive and I don’t think there is a demo or any licensing for indies. Usually when I model a tree I start out with a cylinder and then extrude, move and scale till I get the trunk and branches the way I want them. I add the leaves with a separate material and my game engine imports this as a subset and allows me to tag them as transparent, thus setting the appropriate blending stage when rendering.
There are also several free (low cost) tree generators that let you quickly create trees and export them in the X file format. I think Tree[d] is a good one. Just make sure you read the license and usage terms carefully.