I just responded to a ticket where a user was asking about making motion-reactive visuals with Syphon Receiver. This led me to make an example file demonstrating basic motion tracking and value scaling using the Syphon Receiver, Syphon Stage Output, Eyes, and Limit-Scale Value actors so I thought I'd post it here in case it would be helpful for anyone else.

What does the Syphon Receiver actor do and how can it be used for motion-responsive visuals?

Syphon Receiver is used to pull in Syphon video streams from other applications. If you do not select an incoming Syphon stream in the actor itself by clicking on the "server" input and selecting a Syphon stream from the list, it will not display anything. Syphon Receiver can be used for motion-responsive visuals if you use the Eyes or Eyes++ actor to do motion tracking of a moving body in an incoming Syphon stream and then use the data provided by the Eyes or Eyes++ actor with other Isadora actors. Here's a link with some explanation about motion tracking. To work with motion tracking, you will want to have a good understanding of value scaling. (Value Scaling Tutorial 1, Value Scaling Tutorial 2). Here is an example patch (created in Isadora 3.0.2) which demonstrates how to use Syphon Receiver, do basic motion tracking with the Eyes actor, and gives a simple example of value scaling using the Limit-Scale Value actor.

In the case questions about the function of specific actors (or their inputs/outputs), the actors section of the Isadora 3 Manual has an entry for each actor with these details, so it's always good to look there to learn more about specific actors.

Best wishes,

Woland