System for projecting content to a display surface having user-controlled size, shape and location/direction and apparatus and methods useful in conjunction therewith

A system comprising:

• at least two finger-wearable devices, each comprising:
• a sensor configured to sense at least a pinching of thumb to finger,
• a light source, and
• a controller configured to encode two or more commands in light emitted by said light source, wherein at least one of the commands is responsive to the sensor sensing the pinching;
• a camera;
• a screen;
• and
• a computer associated with said camera and said screen, wherein said computer is configured to:
• cause said screen to display visual content,
• detect, using said camera:
• the light emitted by said light sources of said at least two finger-wearable devices, and
• a location from which said light sources emit the light, trigger different input functionalities in said computer based on:
• the two or more commands encoded in the light emitted by said light sources, and
• the detected location from which said light sources emit the light.