Speedtree style texture blending, how is it done?

somawheels

Speedtree has a branch intersection blending feature

How could i make this blending effect in a 3d package/software?

Obscura

This isn't a texture blending. Its normal smoothing on the intersections.

somawheels

if you look closely, you will notice it is both normal smoothing and texture blending.

Obscura

The weights that were used to tell where to smooth the normals could have been reused in a simple alpha blending between the 2 textures or 2 offset values as well.

frmdbl

It's been a while since I touched SpeedTree, but I remember they used a whole lot of UV channels (7-8).

I think they just blend different channels using vertex colors (or alpha), plus of course adjust the normals.

Certainly there are no additional alpha textures other than the detail texture with alpha.

somawheels

I think you are right on that frmdbl. If i cylinder UV map the branch and trunk, their texture will lign-up at the base.


However, My tree trunk is bendy - not a streight cylinder. Is there anything like a bendable cylinder projection uvmapper?

Obscura

That would be great  I mean if you have a mesh with the uvwmap modifier on it and then a bend modifier ontop of that, it kinda does what you want but I know that isn't good enough. I think what actually happens is they blend between the standard cylinderical mapping and the original uvmap. The cylinderical one blends in at the intersections.

somawheels

I found an easy way to get same uvmapping on branch base as trunk - use the 3dsmax projection modifier.

shabba

Just to give a good idea about what kind of data is being stored in your geometry when exporting /w certain features enabled in SpeedTree. If you arent going to use the branch blending features, you could try adjusting the "Light Seam Reduction" property to affect the normals of the branch you want to blend, there is also a curve that can give you more exact results under "Welding".

In terms of UVs you'll have a difficult time aligning your branch UVs to the parent branch manually and will likely be left with a seam

I'd be interested to know how you got the project modifier to work beyond the initial blend geo up into the rest of the branch?