/// <summary>
/// New version of ShouldStartDrag implemented first in PointerInputModule. This version differs in that
/// for ray based pointers it makes a decision about whether a drag should start based on the angular change
/// the pointer has made so far, as seen from the camera. This also works when the world space ray is
/// translated rather than rotated, since the beginning and end of the movement are considered as angle from
/// the same point.
/// </summary>
private bool ShouldStartDrag(PointerEventData pointerEvent)
{
if (!pointerEvent.useDragThreshold)
{
return(true);
}
if (!pointerEvent.IsSyncVRPointer())
{
// Same as original behaviour for canvas based pointers
return((pointerEvent.pressPosition - pointerEvent.position).sqrMagnitude >= eventSystem.pixelDragThreshold * eventSystem.pixelDragThreshold);
}
else
{
#if UNITY_ANDROID && !UNITY_EDITOR // On android allow swiping to start drag
if (useSwipeScroll && ((Vector3)pointerEvent.SyncVRGetSwipeStart() - Input.mousePosition).magnitude > swipeDragThreshold)
{
return(true);
}
#endif
// When it's not a screen space pointer we have to look at the angle it moved rather than the pixels distance
// For gaze based pointing screen-space distance moved will always be near 0
Vector3 cameraPos = pointerEvent.pressEventCamera.transform.position;
Vector3 pressDir = (pointerEvent.pointerPressRaycast.worldPosition - cameraPos).normalized;
Vector3 currentDir = (pointerEvent.pointerCurrentRaycast.worldPosition - cameraPos).normalized;
return(Vector3.Dot(pressDir, currentDir) < Mathf.Cos(Mathf.Deg2Rad * (angleDragThreshold)));
}
}
protected Vector2 SwipeAdjustedPosition(Vector2 originalPosition, PointerEventData pointerEvent)
{
#if UNITY_ANDROID && !UNITY_EDITOR
// On android we use the touchpad position (accessed through Input.mousePosition) to modify
// the effective cursor position for events related to dragging. This allows the user to
// use the touchpad to drag draggable UI elements
if (useSwipeScroll)
{
Vector2 delta = (Vector2)Input.mousePosition - pointerEvent.SyncVRGetSwipeStart();
if (InvertSwipeXAxis)
{
delta.x *= -1;
}
return(originalPosition + delta * swipeDragScale);
}
#endif
// If not Gear VR or swipe scroll isn't enabled just return original position
return(originalPosition);
}
