<script> function Point2D(x, y) { this.x = x; this.y = y; Point2D.prototype.quadrant = function() { if (x > 0 && y > 0) return "I"; else if (x < 0 && y > 0) return "II"; else if (x < 0 && y < 0) return "III"; else if (x > 0 && y < 0) return "IV"; else if (x == 0) return "x-axis"; else if (y == 0) return "y-axis"; else throw new Error(); } Point2D.prototype.toVector = function() { return new Vector2D(x, y); } Point2D.prototype.distance = function() //求距离 { if (arguments.length == 1 && arguments[0] instanceof Point2D) { return this._point_distance.apply(this, arguments); } else if (arguments.length == 1 && arguments[0] instanceof Vector2D) { return this._vector_distance.apply(this, arguments); } else { throw new Error("Argument Error!"); } } Point2D.prototype._point_distance = function(p) //求两点之间的距离(函数重载) { return (new Vector2D(p,this)).length(); } Point2D.prototype._vector_distance = function(v) //求点到向量的距离(函数重载) { var v1 = new Vector2D(this, v.start); var v2 = new Vector2D(this, v.end);
var area = Math.abs(v1.cross(v2)); //平行四边形面积 = v1 X v2 = |v1v2|sin(v1,v2) return area / v.length(); //平行四边形面积除以底边长度即为点到向量的距离 } } function Vector2D() { if (arguments.length == 2 && arguments[0] instanceof Point2D && arguments[1] instanceof Point2D) { _point_point_Vector2D.apply(this, arguments); } else if (arguments.length == 2 && !isNaN(arguments[0]) && !isNaN(arguments[1])) { _double_double_Vector2D.apply(this, arguments); } else if (arguments.length == 4 && !isNaN(arguments[0]) && !isNaN(arguments[1]) && !isNaN(arguments[2]) && !isNaN(arguments[3])) { _double_double_double_double_Vector2D.apply(this, arguments); } else { throw new Error("Argument Error!"); } } function _point_point_Vector2D(p1, p2) { this.start = p1; this.end = p2; Vector2D.prototype.length = function() //求向量的长度 { return Math.sqrt(this.pond_x() * this.pond_x() + this.pond_y() * this.pond_y()); } Vector2D.prototype.pond_x = function() //x方向分量 { return this.start.x - this.end.x; } Vector2D.prototype.pond_y = function() { return this.start.y - this.end.y; } Vector2D.prototype.cross = function(v) //求向量的交积 P1 X P2 = x1y2 - x2y1 { return this.pond_x() * v.pond_y() - v.pond_x() * this.pond_y(); } } function _double_double_Vector2D(x,y) //重载构造函数Vector2D { this.pointPairs = new Array(); this.pointPairs[0] = new Point2D(0, 0); this.pointPairs[1] = new Point2D(x, y);
_point_point_Vector2D.apply(this, this.pointPairs); } function _double_double_double_double_Vector2D(x1, y1, x2, y2) //重载构造函数Vector2D { this.pointPairs = new Array(); this.pointPairs[0] = new Point2D(x1, y1); this.pointPairs[1] = new Point2D(x2, y2);
_point_point_Vector2D.apply(this, this.pointPairs); } var p1 = new Point2D(0,0); var p2 = new Point2D(10,10); var v1 = new Vector2D(p1,p2); //通过两个点(p1,p2)的方式来构造向量V1 alert("向量v1长度:"+v1.length()); var v2 = new Vector2D(0,0,5,5); //通过四个坐标(x1,y1,x2,y2)的方式来构造向量V2 alert("向量v2长度:"+v2.length()); var v3 = new Vector2D(0,10); //通过指定终点的方式来构造向量V3 alert("向量v3长度:"+v3.length()); alert("向量v1与v2的交积:"+v1.cross(v2)); //求V1 X V2 (因为平行,所以结果为0)
var p3 = new Point2D(10,0); alert("点p1与p3的距离:"+p1.distance(p3)); alert("点p3与向量v1的距离:"+p3.distance(v1)); </script>
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