Detecting swipe gesture direction with Leap Motion

Question

I'm trying to simply get the direction of a swipe gesture with the Leap Motion using the javascript API. My code is:

$(document).ready(function() {
    controller = new Leap.Controller("ws://localhost:6437/");
    listener = new Leap.Listener();

    listener.onFrame = function(controller) {
        var frame = controller.frame();
        var hands = frame.hands();
        var pointables = frame.pointables();

        var gestures = frame.gestures();

        $("#rotationAxis").text(pointables.length);
        $("#gestureDetected").text(gestures[0]);
    }

    controller.addListener(listener);
    controller.enableGesture("swipe", true);
    listener.onConnect = function(controller) {
        // calibrate = new Leap.Calibrate(controller);
        // calibrate.onComplete = function(screen){
        // }
    }
});

I can get the current gesture from the array, but cannot get the type or direction. Any ideas?

Thanks.

Answer 1

If you care about right, left, up, or down, you can compare the absolute value of the horizontal and vertical coordinates of the Swipe direction vector to see if the Swipe is more vertical or more horizontal (and then compare the relevant coordinate to zero to see if the swipe is going right or left, or up or down):

// Setup Leap loop with frame callback function
var controllerOptions = {enableGestures: true};

Leap.loop(controllerOptions, function(frame) {

  if (frame.gestures.length > 0) {
    for (var i = 0; i < frame.gestures.length; i++) {
      var gesture = frame.gestures[i];

      if (gesture.type == "swipe") {
          //Classify swipe as either horizontal or vertical
          var isHorizontal = Math.abs(gesture.direction[0]) > Math.abs(gesture.direction[1]);
          //Classify as right-left or up-down
          if(isHorizontal){
              if(gesture.direction[0] > 0){
                  swipeDirection = "right";
              } else {
                  swipeDirection = "left";
              }
          } else { //vertical
              if(gesture.direction[1] > 0){
                  swipeDirection = "up";
              } else {
                  swipeDirection = "down";
              }                  
          }
       }
     }
  }

})

With a slightly more complex comparison, you could classify swipes as forward or backward, too.