The beginnings of the drunken-scroller stellar.js plugin.

drunken-scroller.js

    $.stellar.positionProperty.stagger = {
        setTop: function ($element, newTop, originalTop) {
            var $elementCoords = $element.position();
            var stellarScrollRatio = parseFloat($element.data('stellar-ratio'));
            var direction = 'top';
            var originalPosition = originalTop;
            var currentPosition = $elementCoords.top;
            var magnitude = newTop - originalTop;
            if ($element.data('stellar-swap-horizontal-and-vertical') == true) {
                if ($element.data('stellar-scroll-horizontal') == false) {
                    return false;
                }
                direction = 'left';
                originalPosition = parseInt($element.data('stellar-starting-left'), 10);
                currentPosition = $elementCoords.left;
                magnitude = magnitude * -1;
            } else {
                if ($element.data('stellar-scroll-vertical') == false) {
                    return false;
                }
            }
            if ('undefined' !== typeof $element.data('stellar-after-in-position')) {
                if (((stellarScrollRatio > 1) && 
                     (magnitude > 0)) ||
                    ((stellarScrollRatio < 1) &&
                     (magnitude < 0))) {
                    switch ($element.data('stellar-after-in-position')) {
                        case 'stay':
                            magnitude = 0;
                            break;
                        case 'reverse':
                            magnitude = magnitude * -1;
                            break;
                        default:
                            break;
                    }
                }
            }
            $element.css(direction, originalPosition + magnitude);
        },
        setLeft: function ($element, newLeft, originalLeft) {
            var $elementCoords = $element.position();
            var stellarScrollRatio = parseFloat($element.data('stellar-ratio'));
            var direction = 'left';
            var originalPosition = originalLeft;
            var currentPosition = $elementCoords.left;
            var magnitude = newLeft - originalLeft;
            if ($element.data('stellar-swap-horizontal-and-vertical') == true) {
                if ($element.data('stellar-scroll-vertical') == false) {
                    return false;
                }
                direction = 'top';
                originalPosition = parseInt($element.data('stellar-starting-top'), 10);
                currentPosition = $elementCoords.top;
                magnitude = magnitude * -1;
            } else {
                if ($element.data('stellar-scroll-horizontal') == false) {
                    return false;
                }
            }
            if ($element.data('stellar-after-in-position')) {
                if (((stellarScrollRatio > 1) && 
                     (magnitude > 0)) ||
                    ((stellarScrollRatio < 1) &&
                     (magnitude < 0))) {
                    switch ($element.data('stellar-after-in-position')) {
                        case 'stay':
                            magnitude = 0;
                            break;
                        case 'reverse':
                            magnitude = magnitude * -1;
                            break;
                        default:
                            break;
                    }
                }
            }
            $element.css(direction, originalPosition + magnitude);
        }
    };