private float GetAngle(Leap.Hand hand)
{
Vector3 proximalAxis = hand.DistalAxis() * -1f;
Vector3 radialAxis = hand.RadialAxis();
if (hand.IsLeft)
{
radialAxis *= -1f;
}
List <float> fingerAngles = new List <float>
{
Vector3.SignedAngle(proximalAxis, hand.GetIndex().Direction.ToVector3(), radialAxis),
Vector3.SignedAngle(proximalAxis, hand.GetMiddle().Direction.ToVector3(), radialAxis),
Vector3.SignedAngle(proximalAxis, hand.GetRing().Direction.ToVector3(), radialAxis),
Vector3.SignedAngle(proximalAxis, hand.GetPinky().Direction.ToVector3(), radialAxis)
};
List <float> fingerAnglesShifted = new List <float>();
foreach (float angle in fingerAngles)
{
float shiftedAngle = angle;
if (angle < -90f)
{
shiftedAngle += 360f;
}
fingerAnglesShifted.Add(shiftedAngle);
}
angle = 0.25f * (fingerAnglesShifted[0] + fingerAnglesShifted[1] + fingerAnglesShifted[2] + fingerAnglesShifted[3]);
return(angle);
}
bool CheckHandForActivation(Leap.Hand hand, bool wasEligibleLastCheck)
{
bool shouldActivate = false;
float latestPinchDistance = GetCustomPinchDistance(hand);
Vector3 palmDir = hand.PalmarAxis();
Vector3 middleDir = hand.GetMiddle().bones[1].Direction.ToVector3();
float signedMiddlePalmAngle = Vector3.SignedAngle(palmDir, middleDir, hand.RadialAxis());
if (hand.IsLeft)
{
signedMiddlePalmAngle *= -1f;
}
Vector3 ringDir = hand.GetRing().bones[1].Direction.ToVector3();
float signedRingPalmAngle = Vector3.SignedAngle(palmDir, ringDir, hand.RadialAxis());
if (hand.IsLeft)
{
signedRingPalmAngle *= -1f;
}
Vector3 indexDir = hand.GetIndex().bones[1].Direction.ToVector3();
float indexPalmAngle = Vector3.Angle(indexDir, palmDir);
Vector3 thumbDir = hand.GetThumb().bones[2].Direction.ToVector3();
float thumbPalmAngle = Vector3.Angle(thumbDir, palmDir);
// Eligibility checks-- necessary, but not sufficient conditions to start
// a pinch, suitable for e.g. visual feedback on whether the gesture is
// "able to occur" or "about to occur."
if (
((!wasEligibleLastCheck &&
signedMiddlePalmAngle >= minPalmMiddleAngle) ||
(wasEligibleLastCheck &&
signedMiddlePalmAngle >= minPalmMiddleAngle
* ringMiddleSafetyHysteresisMult) ||
!requireMiddleAndRingSafetyPinch)
&& ((!wasEligibleLastCheck &&
signedRingPalmAngle >= minPalmRingAngle) ||
(wasEligibleLastCheck &&
signedRingPalmAngle >= minPalmRingAngle
* ringMiddleSafetyHysteresisMult) ||
!requireMiddleAndRingSafetyPinch)
// Index angle (eligibility state only)
&& ((!wasEligibleLastCheck &&
indexPalmAngle < maxIndexAngleForEligibilityActivation) ||
(wasEligibleLastCheck &&
indexPalmAngle < maxIndexAngleForEligibilityDeactivation))
// Thumb angle (eligibility state only)
&& ((!wasEligibleLastCheck &&
thumbPalmAngle < maxThumbAngleForEligibilityActivation) ||
(wasEligibleLastCheck &&
thumbPalmAngle < maxThumbAngleForEligibilityDeactivation))
// Must cross pinch threshold from a non-pinching / non-fist pose.
&& (!requiresRepinch)
)
{
// Conceptually, this should be true when all but the most essential
// parameters for the gesture are satisfied, so the user can be notified
// that the gesture is imminent.
_isGestureEligible = true;
}
#region Update Pinch Strength
// Update global "pinch strength".
// If the gesture is eligible, we'll have a non-zero pinch strength.
if (_isGestureEligible)
{
_latestPinchStrength = latestPinchDistance.Map(0f, pinchActivateDistance,
1f, 0f);
}
else
{
_latestPinchStrength = 0f;
}
#endregion
#region Check: Pinch Distance
if (_isGestureEligible
// Absolute pinch strength.
&& (latestPinchDistance < pinchActivateDistance)
)
{
shouldActivate = true;
}
#endregion
#region Hysteresis for Failed Pinches
// "requiresRepinch" prevents a closed-finger configuration from beginning
// a pinch when the index and thumb never actually actively close from a
// valid position -- think, closed-fist to safety-pinch, as opposed to
// open-hand to safety-pinch -- without introducing any velocity-based
// requirement.
if (latestPinchDistance < pinchActivateDistance && !shouldActivate)
{
requiresRepinch = true;
}
if (requiresRepinch && latestPinchDistance > failedPinchResetDistance)
{
requiresRepinch = false;
}
#endregion
return(shouldActivate);
}
