[kami]

Hi Jeremy

I noticed an unsual behavior when importing older mxm (eg. from the resources page).
http://imageshack.us/g/190/mxme.jpg/

mxm.jpg shows the downloaded mxm in mxed.
r_1.jpg shows the directly imported mxm in rhino. (the displacement is missing)
I then saved the mxm under a different name and imported the new mxm
r_2.jpg shows the new mxm in rhino (displacement still missing, but the texture is showed rotated. how is that even possible?)

I noticed quite often when importing older mxm, that he creates a black layer at the bottom which is kind of useless, but I never noticed, that he sometimes forgets the displacement.

Cheers, Christoph

[JDHill]

I'll take a look -- could you please confirm that this is the material:

• Steel Rope by kurt
  On: 22 May 2008
  Material ID: 3968

[kami]

yes, it's this one
I might have confused r_1 and r_2.jpg. I'm not sure which was the first imported one ...

[JDHill]

Thanks, I was pretty sure that was the material. First, understand that when a V1 MXM is read by the V2 SDK, if its BSDFs were all in Additive mode (I am not sure, it may also depend on the layer weights all being less than 100), then an extra layer will be created in the V2 translation. This layer will be black, and set to Normal blending mode, to give a normal base for the material. You will see why you need this layer if you disable it and re-render the preview -- in this case, without the extra layer, you have two Additive layers @ 60% opacity, and a material which is therefore not opaque. So this is where your extra layer, which is far from useless, comes from. What I don't understand is why the layer is being given a Displacement node; that seems like a bug.

Next, notice that the MXM's active Displacement node (the one in the top "Layer" layer, which is pointed to by the Displacement drop-down in MXED's Material Properties page) is actually disabled in the MXM -- if you render the preview, you'll find it renders without displacement. In this, the result you will get when rendering the material in the plugin is actually correct.

There is one specific problem with the plugin's import, though: the displacement parameters are being read, but the actual displacement node is not being made visible in the plugin's material UI. This means that if you right-click the material node and choose Add Displacement, you'll find that the displacement parameters are already set up correctly. I'll fix this up.

[kami]

There is one specific problem with the plugin's import, though: the displacement parameters are being read, but the actual displacement node is not being made visible in the plugin's material UI. This means that if you right-click the material node and choose Add Displacement, you'll find that the displacement parameters are already set up correctly.

Yeah, I noticed that, when I added a displacement.

I noticed th disabled layer and didn't understand how this worked. Is it even possible to have two displacement layers? In rhino the displacemend is independent of the layers.

The base layer (completely black) is not useless, you are right. It's just making things more complicated than they need to be. So I usually delete it and change the layer above to 100% and normal mode. I know that this gives different results, but the results will be different to 1.0 anyway. But this is just a translation method from 1.0 to 2.0.

[JDHill]

In MXED, you can have one displacement node in each layer, but only one of them is ever active in the MXM -- you select which one is active by selecting its layer name in the Material Properties Displacement dropdown. So the upshot is: an MXM only supports rendering one displacement node. I considered the new setup (MXED used to work like the plugin) to be a little inconvenient and confusing, and guessing it might be changed back at some point, I kept the plugin's representation. I'll most likely keep it this way until V3; if things remains the same then, I'll change the plugin.

On the extra layer in V1 -> V2 translation, just to make things clear, this is outside the plugin's control, since by the time the plugin sees the material's structure, it has already been altered by the SDK.