A fallback avatar is a special avatar shown to users that have your avatar hidden for performance reasons. On Quest, avatars with a "Poor" or "Very Poor" rating are hidden by default and your fallback avatar will always be shown.
Creating a fallback avatar involves uploading an avatar for PC and Quest that both have the "Good" performance rating. Getting this rating for a complex and high quality avatar (like the Rex or Canis Woof) is very difficult. But using a Unity plugin we can easily create a fallback avatar.
Polytool is a Unity plugin to automate the process of creating low poly (high performance) avatars from within Unity - no Blender experience required! Purchase the tool from Gumroad and install it into your Unity project.
Open Polytool and in the list of presets select "VRChat PC (Good, Fallback-compatible)". This does several things:
- lowers your polygon count to less than 70,000
- combines your skinned meshes into one single mesh
- reduces the bone count to less than 150
- other optimizations
Note: For avatars with a high bone count (eg. a Rex with a lot of clothing) you might need to remove some of them to reach that 150 bone count.
Apply Polytool! After a few minutes it should hide your original avatar and show you the fallback one. Go into the VRChat SDK and ensure that it says it is fallback compatible. If it is, upload it!
Note: Ensure your blueprint ID is correct. If you are making a new fallback avatar it should be empty!
Now select the "VRChat Quest (Good, Fallback-compatible)" preset and run it again to output a Quest version. Ensure that your blueprint ID is the same for both PC and Quest so that the game understands it all correctly.
Note: For avatars with a high bone count (eg. Rex or Canis Woof) you will need to remove a lot of bones to get the 90 limit. I recommend you remove the hair and tail ones first.
Inside the VRChat client view your non-fallback avatar and where it asks you for a fallback, select the newly created one! Done!