#ofxEnveloper ofxEnveloper is an openFrameworks addon that converts gestures into an envelope type of graphical information, by recognising inflection points from the gesture. Thresholds for horizontal and vertical lines can also be defined. It is particularly aimed for animation and sound applications, and for use with drawing surfaces (such as Wacom tablets or touchscreen interfaces).

Possible uses:

• audio effect or EQ envelopes;
• animation curves;
• creation/manipulation of audio and/or visual sequences;
• arpeggiators.

Compatibility: openFrameworks 0.9.0

#How it works

• Create an ofxEnveloper object, specifying pixel thesholds for detection of vertical and horizontal lines (default is 0).
• While performing a gesture, points are added to the envelope recognition with the push_back() method.
• Gesture and interpolation can be drawn while gesture is executed, using drawGesture() and drawInterpolation() (*).
• Once a gesture is completed, the getEnvelope() method can be executed.
• The getPoints() method can then be used to retrieve the envelope points.
• A scale() method is provided by scaling an envelope from an ofRectangle object to another.
• The clear() method clears the envelope recognition.

(*) ofxEnveloper relies on Memo Akten’s ofxMSAInterpolator.

Dependencies: ofxMSACore and ofxMSAInterpolator.

#Examples The example-scaling illustrates how a gesture can result in a scaled envelope.

How to run the example:

• Use projectGenerator to create a new project
• Select the addons: ofxEnveloper, ofxMSACore, ofxMSAInterpolator
• Replace the resulting src folder with the example's src folder

#Credits Code by Fiore Martin. Examples by Fiore Martin and Nuno Correia.

ofxEnveloper is part of the DePIC and Enabling AVUIs research projects. DePIC is hosted by Queen Mary, University of London and funded by EPSRC. Enabling AVUIs is hosted by Goldsmiths, University of London and funded by the Marie Curie EU fellowship program.