XGen Arbitrary Primitive Generator is the system used for hair in both Disneys Zootopia and Pixars Toy Story 3
Xgen lets you create and groom hair, fur, feathers, grass, foliage, trees, and rocks.
It’s a great tool for set dressing and is a serious contender to Peregrine labs Yeti, especially because you don’t have to be a rocket scientist to make it work.
Below is an example of fur rendered with Arnold and Xgen
Export and import of groom and collection:
When you set your maya project path you will find a xgen folder in there, this is where you can find your .xgen file and your groom data in case you want to save time not exporting the groom.
If you want to export your groom and description to a specific folder for use in production, you can choose to export collection directly from the xgen tab.
This is how your exported groom looks in finder: four foulders “bend, orient, length and width” along with your xgen file which is your collection.
To import your groom onto the same character but in a different maya scene you simply select the geometry and click xgen -> import collections or descriptions.
Once the window shows up, direct maya to the folder where you saved your .xgen file.
Once you click import you will see that your description is connected to your geometry, but your groom is still missing.
If you go to your xgen tab again and select import Groom, you will see another window where you need to direct maya to the folder containing your exported groom “4 folders mentioned above”.
Once this is done and you cilck import you should see your groom applied in your new scene.
Here’s a few tips on how to use Xgen for Maya.
Arnold Xgen shading and rendering overview:
Setup arnold shader with ptex map:
Step 1: Make sure to set your maya project path to somewhere you can find.
Step 2: assign your arnold shader to the description of your choise.
Step 3: create a custom attribute on the description and use an expression to get the ptex texture map.
the expression can look like this: map(‘N:/deer/asset/char/deer/texture/deer_fur.ptx’)
Step4: create a aiUserDataColor node and enter the name of the custom attribute you created in step 3.
Step5: plug the aiUserDataColor output into the color of your shader and done!
Arnold usually gamma corrects 8 bit maps automatically, but in this case, since we connect the map to the shader through the aiUserDataColor1 we need to manually gamma correct our map.
This only applies if your texture map is 8bit.
Converting an existing texture map to Ptex using Mari:
Baoba part fur groom: