Allow external programs to set animation parameters of 3.0 avatars. This allows people to use devices that are not supported by VRC natively (and would take way longer to implement than this proposed solution). For example: eye tracking, facial tracking, tracking of the thumb state of Index controllers, or even heart rate monitors. This also opens up the possibility to use a controller to simulate arm movement.

Setting the animation parameters could be done via RPC, similarly how games communicate with Discord with Rich Presence. A small example would an application that uses Vive's SRanipal for eye tracking to send "{ LeftEyeDirectionX : -0.58, LeftEyeDirectionY : 0.14 }" and parameters with the same name would be set. Want an animation that triggers when you pick up your drink? You can!

This feature should be disabled by default to prevent unwanted programs interacting with VRChat.

This would open up SDK3 to even more cool and creative ideas, and allows people to play around with the latest tech.