Wednesday, December 29, 2021

Using Old Morphs in Version 1.6.1

In version 1.6.0 of the DAZ Importer the new morph system was introduced. It is not compatible with the old morph system from version 1.5.1, but old characters could still be used in version 1.6.0 because code necessary to deal with old morphs was kept. However, in the current development version, which will eventually become 1.6.1, support for the old morphs has been dropped. So morphs made for characters in version 1.5.1 do not work in the current version. Fortunately, there is a way to fix this, using stripped runtime system that was included in the 1.6.0 release.

Here we have created a character in version 1.5.1 ( the last version compatible with Blender 2.79) of the DAZ Importer, and loaded some morphs.
If we append the character into a new Blender file and run the latest version of the DAZ Importer, the morphs do not work. The sliders show up in the Morph panel, but nothing happens if we change them.
To fix this, go to the Scripting tab and open the stripped runtime system which was included in the 1.6.0 release. We need to load the file in the runtime_stripped folder.
Register the script in the Text menu, save the blend file and reload it. This is important because the script does not take effect until the file is reloaded.
And now the old morphs work.

There is an important limitation to this approach. The old and new morph systems do not work together, so the old morphs will stop working if you load new ones in version 1.6.1. If you want to add morphs, you need to go back to version 1.5.1 and load the morphs there.

Before the old morph system was introduced, there was an even older morph system. There was a conversion utility, which was described in the announcement, but I haven't tested to use it.

Wednesday, December 15, 2021

Custom JCMs and Adjusters

Recently some problems with loading custom JCMs (Joint Corrective Morphs) were reported. It turned out that the code contained a hack to avoid problems with reloading JCMs, and that piece of code didn't work well. The problem should be resolved in the latest development version, but looking into this made me better understand how custom JCMs work and how they are related to the corresponding FBMs (Full Body Morphs).

First we import Aiko into Blender with Mesh Fitting set to DBZ File.

Import the standard JCMs (Import JCMs button) and bend the left elbow. The corrective shapekeys are driven by the bone rotation as expected. However, these shapekeys where made for the basic Genesis 8 Female, and we get better deformation if we import the JCMs that were designed specifically for Aiko.
For this we use the Import Custom Morphs tool. In the file selector, use "pjcm" as the filter to limit the selection to the JCMs (more precisely to the pJCMs, eJCMs are not imported), and import everything.
And we see that the Aiko-specific shapekeys are also driven by the bone rotations.

However, there is a catch. The final shapekey values are multiplied with the strength of the Aiko FBM (Full Body Morph). If the Aiko FBM is not imported, which it wasn't since we only imported the pJCMs, behind the scenes the FBM strength is set to 1, and everything is fine. But let's see what happens if we import the Aiko morphs.

So we import the Aiko FBM and FHM, and suddenly the Aiko corrective shapekeys are set to zero.
What happens was that by importing the Aiko FBM, we created a new property that multiplies the strength of the JCMs, and since that property was set to zero, the JCMs are zero too.
So if Aiko 8 Body = 0, the left forearm JCMs are zero too, even if the elbow is bent.
If we set Aiko 8 Body = 1, the non-zero JCM values reappear.
Alas, we can not set the Aiko FBM and FHM to one, because the Aiko morphs were already baked into the mesh when it was loaded with Mesh Fitting set to DBZ File, and thus the Aiko morphs are applied twice.

The way to decouple the JCM strength from the FBM strength is to use adjusters. Let us go back and import the Aiko JCMs again, but this time we enable the Use Adjusters option.
Now a new slider called Adjust Custom/aiko appears at the to of the aiko category. This property replaces the FBM value as a JCM multiplier. So if Adjust Custom/aiko = 1.0, the Aiko JCMs have the right values even if the Aiko FBM = 0.
If we reduce the value of the adjuster, the morph values are reduced accordingly. This can be used if you have mixed character. If you create a character which is 30% Aiko and 70% Victoria, say, you can import both the Aiko and Victoria custom JCMs, and set Adjust Custom/aiko = 0.3 and Adjust Custom/victoria = 0.7, to get the JCM mix which is right for that character.

Sunday, December 12, 2021

Better Decals

A decal is projected from an empty (the projector) onto a mesh. In an earlier post we discussed a tool for adding decals to DAZ meshes. However, there were some shortcomings which made the decal tool rather unusable:
  1. The decal were also projected on surfaces that are facing away from the empty.
  2. Decals could not cross material boundaries, forcing us to some very convoluted constructions.
  3. Only images with an alpha channel were supported, but not jpeg images with masks.
  4. There was no indication in which direction the decal was projected.

Recently Alessandro Padovani and Xin made me revisit the decal tool, with some nice improvements.

Select the mesh and press Advanced Setup > Materials > Make Decal. A file selector opens.

First we can select the materials that the decal will be added too. We can select one or several materials. The buttons at the top work in the same way as in the material editor or the UDIM tool. The remaining options are:

  • Channel: The channel that the decal should be added to, e.g.
    • Diffuse Color
    • Principled Base Color
    • Bump
  • Reuse Empty: If selected, an existing empty in the scene is used to project the decal, otherwise a new empty is created. If the decal affects multiple channels, enable this after the first channel has been loaded.
  • Empty: A list of available empties. If None is selected, a new empty is created.
  • Use Mask: Use a separate mask image for transparency. If disabled the image's alpha channel is used instead.
  • Decal Mask: Path to the mask file. A file selector for the mask is below the Make Decal button.
  • Blend Type: How the decal is blended with the base texture (Mix, Multiply, etc.). The default is Mix.
An empty with the shape of a flattened cube is created at the origin. The extent of the cube is approximately the region where the decal lives. Move, scale and rotate the empty until the decal looks as desired.

Next we want to add a second decal, which is a jpeg file. Since jpeg images don't have an alpha channel, we need to add a separate mask image. Before pressing Make Decal, set the Decal Mask below it, using the folder icon. In the file selector that opens, select the heart-mask.jpg file.

Now press Make Decal again and enable Use Mask. A new field with the previously selected mask file appears. Now select the heart.jpg file.

There are now two nodes that modify the diffuse texture. The node groups have the same label, but they are really different node groups because different empties control the location of the decal.

 Position the second decal in the same way as the first.

To make a decal cross a material boundary, it must be assigned to both materials. The Skin button selects the skin materials, i.e. the torso, face, arms and legs materials in this case. We select the jpeg version of the heart, but if we set the blend type to Multiply the white background will not show up.

Position the decal on the shoulder where the torso and arm materials meet. Note how the problems we encountered in the previous post do not arise anymore.

Finally we import a star decal. Only the arms material is selected, and we enable Reuse Empty. In the list of available empties, select the one that we created last.

The star decal immediately appears on the shoulder. Note that the tip of the star is cut off, since it was only assigned to the arms material. This is a rather artificial example. Normally we reuse an empty if we load related decals to different channels, e.g. diffuse and bump.

The shape of the cube gives a visual cue about the extent of the decal. If the cube is scaled in the local Z direction, i.e. it is made deeper, the decal may show up on the other side of the mesh as well, as in the picture below.

We can control the visibility of the decals with the Set Shell Visibility tool which appears in the Visibility panel when the mesh is the active object. In the popup dialog there is an entry for each decal. The same tool also controls the visibility of the shell nodes. The Insert Keys option allows us to animate the decal visibility.

Finally we vertex parent the decal empties to the mesh, so they move with the mesh when it is posed.

And here the mesh is posed with the decals in place.