GetOverlapX = function (body1, body2, overlapOnly, bias)
{
    var overlap = 0;
    var maxOverlap = body1.deltaAbsX() + body2.deltaAbsX() + bias;

    if (body1._dx === 0 && body2._dx === 0)
    {
        //  They overlap but neither of them are moving
        body1.embedded = true;
        body2.embedded = true;
    }
    else if (body1._dx > body2._dx)
    {
        //  Body1 is moving right and / or Body2 is moving left
        overlap = body1.right - body2.x;

        if ((overlap > maxOverlap && !overlapOnly) || body1.checkCollision.right === false || body2.checkCollision.left === false)
        {
            overlap = 0;
        }
        else
        {
            body1.touching.none = false;
            body1.touching.right = true;

            body2.touching.none = false;
            body2.touching.left = true;

            if (body2.physicsType === CONST.STATIC_BODY && !overlapOnly)
            {
                body1.blocked.none = false;
                body1.blocked.right = true;
            }

            if (body1.physicsType === CONST.STATIC_BODY && !overlapOnly)
            {
                body2.blocked.none = false;
                body2.blocked.left = true;
            }
        }
    }
    else if (body1._dx < body2._dx)
    {
        //  Body1 is moving left and/or Body2 is moving right
        overlap = body1.x - body2.width - body2.x;

        if ((-overlap > maxOverlap && !overlapOnly) || body1.checkCollision.left === false || body2.checkCollision.right === false)
        {
            overlap = 0;
        }
        else
        {
            body1.touching.none = false;
            body1.touching.left = true;

            body2.touching.none = false;
            body2.touching.right = true;

            if (body2.physicsType === CONST.STATIC_BODY && !overlapOnly)
            {
                body1.blocked.none = false;
                body1.blocked.left = true;
            }

            if (body1.physicsType === CONST.STATIC_BODY && !overlapOnly)
            {
                body2.blocked.none = false;
                body2.blocked.right = true;
            }
        }
    }

    //  Resets the overlapX to zero if there is no overlap, or to the actual pixel value if there is
    body1.overlapX = overlap;
    body2.overlapX = overlap;

    return overlap;
}
Calculates and returns the horizontal overlap between two arcade physics bodies and sets their properties
accordingly, including: `touching.left`, `touching.right`, `touching.none` and `overlapX'.

@function Phaser.Physics.Arcade.GetOverlapX
@since 3.0.0

@param {Phaser.Physics.Arcade.Body} body1 - The first Body to separate.
@param {Phaser.Physics.Arcade.Body} body2 - The second Body to separate.
@param {boolean} overlapOnly - Is this an overlap only check, or part of separation?
@param {number} bias - A value added to the delta values during collision checks. Increase it to prevent sprite tunneling(sprites passing through another instead of colliding).

@return {number} The amount of overlap.