This is very annoying. On GitHub - vorpalrobotics/VorpalHexapod: Arduino code for both the Vorpal Hexapod and Vorpal Hexapod Gamepad. it says:
Please see the project wiki on our website for complete details including how to build the robot, where to download the libraries
but I find no mention of the libraries anywhere in their wiki. I don't understand why people don't just add a comment after the #include directives for external dependencies explaining where they can be found.
I did find a Pixy library via a Google search. You can install it by:
- Download http://cmucam.org/attachments/download/1157/arduino_pixy-0.1.7.zip
- (In the Arduino IDE) Sketch > Include Library > Add .ZIP library...
- Select the downloaded file
- Click "Open"