Libgdx 双指平移而不是单指平移？

Question

I've overridden the LibGdx Pan gesture method for a different functionality (a selector). However, I want the pan functionality to use two fingers(pointers) instead. Is this possible?

It's the same question as this post, however his is specific to iPhone and not LibGdx: How to implement the traditional imageView-inside-a-scrollView pan gesture with two fingers instead of one?

the pan() method will only fire with one finger, not two. I was thinking of keeping track of number of fingers used, by setting a variable in touchDown() using the int pointer variable, however the pan() method will not fire when there are 2 fingers in use.

Any suggestions? Cheers

Answer 1

我设法围绕pinch()方法来计算组合的两个手指平移和缩放手势，而不是使用zoom() 。

Answer 2

Here's some code which achieves this using the pinch method, by looking at how far the first finger has been dragged from its initial position. The second finger is ignored.

Gdx.input.setInputProcessor(new GestureDetector(new GestureDetector.GestureAdapter() {
    @Override
    public boolean pinch(Vector2 initialPointer1, Vector2 initialPointer2, Vector2 pointer1, Vector2 pointer2) {
        float panAmount = pointer1.x - initialPointer1.x;
        // ...
        return true;
    }
})));

Answer 3

After 3+ years of research I finally made it.

@Override
public boolean pinch(Vector2 initialPointer1, Vector2 initialPointer2, Vector2 pointer1, Vector2 pointer2) {
    // Calculate distances
    float initialDistance = initialPointer1.dst(initialPointer2);
    float distance = pointer1.dst(pointer2);
    // Calculate pinch coordinates
    float initialPinchX = (initialPointer1.x + initialPointer2.x) / 2;
    float initialPinchY = (initialPointer1.y + initialPointer2.y) / 2;
    float pinchX = (pointer1.x + pointer2.x) / 2;
    float pinchY = (pointer1.y + pointer2.y) / 2;
    // This to avoid first time zooming or panning horrible behavior
    if (lastZoomDistance == 0) {
        lastZoomDistance = initialDistance;
    }
    if (lastPinchX == lastPinchY && lastPinchX == 0) {
        lastPinchX = initialPinchX;
        lastPinchY = initialPinchY;
    }
    // Zoom
    float distanceDifference = distance - lastZoomDistance;
    camera.zoom -= distanceDifference / 300;
    // Pan
    float deltaX = (pinchX - lastPinchX) * camera.zoom;
    float deltaY = (pinchY - lastPinchY) * camera.zoom;
    camera.translate(-deltaX, deltaY);
    // We need to update these for future calculations
    lastZoomDistance = distance;
    lastPinchX = (pointer1.x + pointer2.x) / 2;
    lastPinchY = (pointer1.y + pointer2.y) / 2;
    return false;
}

Answer 4

To add onto Luis' answe, sometimes you may want Pan/ Zoom to act as exclusive actions (only one can happen at a time). If that's what you're after, this may be useful

val targetVector1 = Vector2(pointer1).sub(initialPointer1)
val targetVector2 = Vector2(pointer2).sub(initialPointer2)

val isZoom = targetVector1.hasOppositeDirection(targetVector2)
val isPan = !isZoom