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Yahoo! UI Library

animation  2.5.0

Yahoo! UI Library > animation > Bezier.js (source view)

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/**
 * Used to calculate Bezier splines for any number of control points.
 * @class Bezier
 * @namespace YAHOO.util
 *
 */
YAHOO.util.Bezier = new function() {
    /**
     * Get the current position of the animated element based on t.
     * Each point is an array of "x" and "y" values (0 = x, 1 = y)
     * At least 2 points are required (start and end).
     * First point is start. Last point is end.
     * Additional control points are optional.     
     * @method getPosition
     * @param {Array} points An array containing Bezier points
     * @param {Number} t A number between 0 and 1 which is the basis for determining current position
     * @return {Array} An array containing int x and y member data
     */
    this.getPosition = function(points, t) {  
        var n = points.length;
        var tmp = [];

        for (var i = 0; i < n; ++i){
            tmp[i] = [points[i][0], points[i][1]]; // save input
        }
        
        for (var j = 1; j < n; ++j) {
            for (i = 0; i < n - j; ++i) {
                tmp[i][0] = (1 - t) * tmp[i][0] + t * tmp[parseInt(i + 1, 10)][0];
                tmp[i][1] = (1 - t) * tmp[i][1] + t * tmp[parseInt(i + 1, 10)][1]; 
            }
        }
    
        return [ tmp[0][0], tmp[0][1] ]; 
    
    };
};

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