[brodie_geers]

Are others seeing this behavior. With the hair modifier when I start the Fire preview up it renders fine but then when I modify the hair parameters it doesn't update. Reexport causes the hair to disappear and the only way to update is to close and restart the window.

-Brodie

[Bogdan Coroi]

It's a very complicated issue to support properly because of how Max gives us the hair. When asked for the hair, Max generates a file with ALL the hair systems in the scene and that takes ages to export when having textures applied. When you move or change something in the scene, Max sends us loads of retarded messages that can't be filtered and the probability to have all the hairs in the scene exported hundred of times is insanely high, not to mention that you won't be able to see anything in FIRE or even to work with Max. So the only workaround is to use the reexport button. We'll try to find a way to make the workflow for you guys better in Max FIRE with hair, but we haven't come up with anything yet.

[brodie_geers]

As I said though, "Reexport causes the hair to disappear and the only way to update is to close and restart the window." The Reexport button isn't working for me. I guess this isn't working as intended then in my case?

Could you explain briefly how to properly UV map the hair in 3ds Max? I'm fairly new to both hair and channels and I'm having a difficult time figuring out how to create the 2 necessary channels and uv map them.

-Brodie

[Bogdan Coroi]

Reexport button should work and you can consider it a bug atm. We'll look into it.

Regarding hair UV mapping I will quote Mihnea:

The hair does not inherit the material from the base object. You need to expand the "mr Parameters" rollup, enable "Apply mr Shader" and drag a Maxwell material onto the material button.

Max hair does not generate root UVs. You cannot map a texture on channel 2, that information only applies to hair systems which generate root UVs (Shave in Maya, Ornatrix and Hairtrix in Max).

To be able to map a texture on the hairs, you need to do the following:

1. Apply the texture on the tip color and/or root color controls in the "Material Parameters" rollup of the hair.
2. Make a Maxwell material and apply a solid white texture on reflectance 0. It won't work if you just set the refl0 color to white, it needs a texture (this is a limitation of the engine at the moment). Leave the texture on channel 0 (the actual UVs won't matter anyway, since the texture is white everywhere).
3. Apply the maxwell material on the "mr shader" button.

What will happen now is that Max hair will generate colors for each vertex of the hair based on the textures you applied on root/tip color, as well as all the other material parameters (hue variation, fading etc.). These vertex colors will be exported to Maxwell, which will multiply them by the values sampled from the texture you have on the material. Since the texture is white, the original colors will come through unchanged.

The good part is that you can use the same workflow even if you don't need textures on the hair. If you apply the material as described here, you will see that you can use the root/tip color controls on the hair modifier, and the render will look the same as it would look with scanline/mental ray (except for the differences in lighting, obviously).

You can find a sample scene here. It has a black/white checker applied on root and tip color and the render should look like this:



PS: using textures on the root/tip color will increase the hair export time, but there's nothing we can do about that, all the time is taken by Max itself evaluating the colors.