AS3 Vector2D 详细类

package  {/** * Vector2D * Purpose: Utility class to assist in Vector manipulation in a 2D environment * @author Shiu * @version 1.09 August 2011 * @version 2.022 August 2011 */public class Vector2D {private var _vecX:Number;private var _vecY:Number;/** * Constructor of Vector2D * @parammc_xx-component of vector * @parammc_yy-component of vector */public function Vector2D(mc_x:Number, mc_y:Number) {this._vecX = mc_x;this._vecY = mc_y;}/** * Provision for an alternate constructor * @parammagMagnitude of vector * @paramang_rad Orientation of vector in radians */public function polar (mag:Number, ang_rad:Number):void{this._vecX = mag*Math.cos(ang_rad);this._vecY = mag*Math.sin(ang_rad);}/** * Accessors of individual x-component */public function set x(new_x:Number):void{this._vecX = new_x;}public function get x ():Number{return this._vecX;}/** * Accessors of individual y-component */public function set y(new_y:Number):void{this._vecY = new_y;}public function get y ():Number{return _vecY;}/** * Method to obtain the vector * @return A vector array of x and y components */public function getVector ():Vector.<Number>{return new <Number>[_vecX, _vecY]}/** * Method to obtain current angle of vector * @return Angle in radians */public function getAngle ():Number {return Math.atan2(_vecY, _vecX);}/** * Method tl alter current angle of vector * @paramang_rad New angle for current vector in radians */public function setAngle(ang_rad:Number):void{var mag_current:Number = this.getMagnitude();this.polar(mag_current, ang_rad);}/** * Method to obtain current magnitude of vector * @return Magnitude of type Number */public function getMagnitude():Number{return Math.sqrt(_vecX * _vecX + _vecY * _vecY);}/** * Method ot alter current magnitude of vector * @parammagnitude New magnitude of vector */public function setMagnitude(magnitude:Number):void{var ang_current:Number = this.getAngle();this.polar(magnitude, ang_current);}/** * Method to invert both x and y components of vector */public function invert():void{_vecX *= -1;_vecY *= -1;}/** * Version 2.0 * Method to invert only the x-component of Vector2D */public function invertX():void{_vecX *= -1;}/** * Version 2.0 * Method to invert only the x-component of Vector2D */public function invertY():void{_vecY *= -1;}/** * Version 2.0 * Method to scale current vector by a scalar magnitude * @parammultiplier A scalar number to mulitply current vector */public function scale (magnitude:Number):void{_vecX *= magnitude;_vecY *= magnitude;}/** * Method to generate a copy of current vector * @return A copy of current vector */public function clone ():Vector2D{var clone1:Vector2D = new Vector2D(_vecX, _vecY);return clone1;}/** * Method to perform subtration on current vector * @paramtoMinus A vector to minus current vector * @return A copy of subtration product */public function minus(toMinus:Vector2D):Vector2D{var newX:Number = this._vecX - toMinus.x;var newY:Number = this._vecY - toMinus.y;return new Vector2D(newX, newY);}/** * Method to perform addition on current vector * @paramtoAdd A vector to add onto current vector * @return A copy of addition product */public function add(toAdd:Vector2D):Vector2D{var newX:Number = this._vecX + toAdd.x;var newY:Number = this._vecY + toAdd.y;return new Vector2D(newX, newY);}/** * Version 2.0 * Method to multiply current vector with a certain magnitude * @parammultiplier * @return A copy of the multiplied product */public function multiply(multiplier:Number):Vector2D{var newX:Number = this._vecX * multiplier;var newY:Number = this._vecY * multiplier;return new Vector2D(newX, newY);}/** * Method to rotate current vector * @paramangle_rad Angle in radian to rotate current vector * @paramoffset A vector to offset current circular into an eliptical course * @return A copy of the rotated vector */public function rotate(angle_rad:Number):Vector2D{var newX:Number = _vecX * Math.cos(angle_rad) - _vecY * Math.sin(angle_rad);var newY:Number = _vecX * Math.sin(angle_rad) + _vecY * Math.cos(angle_rad);return new Vector2D(newX, newY);}/** * Method to obtain vector unit of current vector * @return A copy of normalised vector */public function normalise():Vector2D{return new Vector2D(this._vecX/this.getMagnitude(), this._vecY/this.getMagnitude())}/** * Method to perform dot product with another vector * @paramvector2 A vector to perform dot product with current vector * @return A scalar number of dot product */public function dotProduct(vector2:Vector2D):Number{var componentX:Number = this._vecX * vector2.x;var componentY:Number = this._vecY * vector2.y;return componentX+componentY;}/** * Method to perform vector product of current vector with input vector * @paramvector2 A vector to perform vector product with current vector * @return The magnitude of pseudo-vector on z-axis */public function vectorProduct(vector2:Vector2D):Number {return this._vecX * vector2.y - this._vecY * vector2.x;}/** * Method to obtain the smaller angle, in radian, sandwiched from current vector to input vector * @paramvector2 A vector to bound the angle * @return Angle in radian, positive is clockwise, negative is anti-clockwise */public function angleBetween(vector2:Vector2D):Number{//get normalised vectorsvar norm1:Vector2D = this.normalise();var norm2:Vector2D = vector2.normalise();//dot product of vectors to find anglevar product:Number = norm1.dotProduct(norm2);product = Math.min(1, product);var angle:Number = Math.acos(product);//sides of angleif (this.vectorProduct(vector2) < 0) angle *= -1return angle;}/** * Method to obtain the projection of current vector on a given axis * @paramaxis An axis where vector is projected on * @return The projection length of current vector on given axis */public function projectionOn(axis:Vector2D):Number{return this.dotProduct(axis.normalise())}}}