File: src\geom\Line.ts
/**
*
* @module Kiwi
* @submodule Geom
*/
module Kiwi.Geom {
/**
* A Line object has two meanings depending on the situation you need.
* Either an infinte line through space (this is the usual meaning of a Line)
* OR it can be a Line Segment which just exists between the TWO points you specify.
*
* @class Line
* @namespace Kiwi.Geom
* @constructor
* @param [x1=0] {Number} Starting location of the line on the x-axis.
* @param [y1=0] {Number} Starting location of the line on the y-axis.
* @param [x2=0] {Number} End location of the line on the x-axis.
* @param [y2=0] {Number} End location of the line on the y-axis.
* @return {Kiwi.Geom.Line} This Object
*
*/
export class Line {
constructor(x1: number = 0, y1: number = 0, x2: number = 0, y2: number = 0) {
this.setTo(x1, y1, x2, y2);
}
/**
* Returns the type of this object
* @method objType
* @return {string} "Line"
* @public
*/
public objType() {
return "Line";
}
/**
* X position of first point on the line.
* @property x1
* @type Number
* @public
*/
public x1: number = 0;
/**
* Y position of first point on the line.
* @property y1
* @type Number
* @public
*/
public y1: number = 0;
/**
* X position of second point.
* @property x2
* @type Number
* @public
*/
public x2: number = 0;
/**
* Y position of second point.
* @property y2
* @type Number
* @public
*/
public y2: number = 0;
/**
* Makes a clone of this Line.
* The clone can either be a new Line Object,
* Otherwise you can pass a existing Line Object that you want to be a clone of this one.
*
* @method clone
* @param [output=Line] {Kiwi.Geom.Line}
* @return {Kiwi.Geom.Line}
* @public
*/
public clone(output: Line = new Line): Line {
return output.setTo(this.x1, this.y1, this.x2, this.y2);
}
/**
* Make this Line a copy of another passed Line.
* @method copyFrom
* @param source {Kiwi.Geom.Line} source
* @return {Kiwi.Geom.Line}
* @public
*/
public copyFrom(source: Line): Line {
return this.setTo(source.x1, source.y1, source.x2, source.y2);
}
/**
* Make another passed Line a copy of this one.
* @method copyTo
* @param target {Kiwi.Geom.Line} target
* @return {Kiwi.Geom.Line}
* @public
*/
public copyTo(target: Line): Line {
return target.copyFrom(this);
}
/**
* Used to set all components on the line.
* @method setTo
* @param [x1=0]{Number} X component of first point.
* @param [y1=0]{Number} Y component of first point.
* @param [x2=0]{Number} X component of second point.
* @param [y2=0]{Number} Y component of second point.
* @return {Kiwi.Geom.Line}
* @public
*/
public setTo(x1: number = 0, y1: number = 0, x2: number = 0, y2: number = 0): Line {
this.x1 = x1;
this.y1 = y1;
this.x2 = x2;
this.y2 = y2;
return this;
}
/**
* Get the length of the Line as a Line Segment.
* @property length
* @type number
* @readOnly
* @public
*/
public get length(): number {
return Math.sqrt((this.x2 - this.x1) * (this.x2 - this.x1) + (this.y2 - this.y1) * (this.y2 - this.y1));
}
/**
* Get the y of a point on the line for a given x.
* @method getY
* @param x {Number}
* @return {Number}
* @public
*/
public getY(x: number): number {
if (this.x1 == this.x2)
return null;
else
return this.slope * x + this.yIntercept;
}
/**
* Get the angle of the line.
* @property angle
* @type Number
* @readOnly
* @public
*/
public get angle(): number {
return Math.atan2(this.y2 - this.y1, this.x2 - this.x1);
}
/**
* Get the slope of the line (y/x).
* @property slope
* @type Number
* @readOnly
* @public
*/
public get slope(): number {
return (this.y2 - this.y1) / (this.x2 - this.x1);
}
/**
* Get the perpendicular slope of the line (x/y).
* @propery perpSlope
* @type Number
* @readOnly
* @public
*/
public get perpSlope(): number {
return -((this.x2 - this.x1) / (this.y2 - this.y1));
}
/**
* Get the y intercept for the line.
* @property yIntercept
* @type Number
* @readOnly
* @public
*/
public get yIntercept(): number {
return (this.y1 - this.slope * this.x1);
}
/**
* Check if a point is on the line.
* @method isPointOnLine
* @param x {Number}
* @param y {Number}
* @return {boolean}
* @public
*/
public isPointOnLine(x: number, y: number): boolean {
if ((x - this.x1) * (this.y2 - this.y1) === (this.x2 - this.x1) * (y - this.y1))
{
return true;
}
else
{
return false;
}
}
/**
* Check if the point is both on the line and within the line segment.
* @method isPointOnLineSegment
* @param x {Number}
* @param y {Number}
* @return {boolean}
* @public
*/
public isPointOnLineSegment(x: number, y: number): boolean {
var xMin = Math.min(this.x1, this.x2);
var xMax = Math.max(this.x1, this.x2);
var yMin = Math.min(this.y1, this.y2);
var yMax = Math.max(this.y1, this.y2);
if (this.isPointOnLine(x, y) && (x >= xMin && x <= xMax) && (y >= yMin && y <= yMax))
{
return true;
}
else
{
return false;
}
}
/**
* Check to see if this Line object intersects at any point with a passed Line.
* Note: Both are treated as extending infinately through space.
* Functions as an alias for the 'Kiwi.Geom.Intersect.lineToLine' method.
*
* @method intersectLineLine
* @param line {Kiwi.Geom.Line} The line you want to check for a Intersection with.
* @return {Kiwi.Geom.IntersectResult} The Intersect Result containing the collision information.
* @public
*/
public intersectLineLine(line): IntersectResult {
return Kiwi.Geom.Intersect.lineToLine(this,line);
}
/**
* Get a line perpendicular to the line passing through a given point.
*
* @method perp
* @param x {Number}
* @param y {Number}
* @param [output] {Kiwi.Geom.Line} The line object that the result should be output to. Creates a new Line if one is not passed.
* @return {Kiwi.Geom.Line}
* @public
*/
public perp(x: number, y: number, output: Line=new Line): Line {
var pt;
// For a horizontal line, the output is a vertical line.
if ( this.y1 === this.y2 ) {
output.setTo( x, y, x, this.y1 );
return output;
}
// For a vertical line, the output is a horizontal line.
if ( this.x1 === this.x2 ) {
output.setTo( x, y, this.x1, y );
return output;
}
var yInt: number = (y - this.perpSlope * x);
if ( x !== 0 ) {
pt = this.intersectLineLine({ x1: x, y1: y, x2: 0, y2: yInt });
} else {
pt = this.intersectLineLine({ x1: x, y1: y, x2: 1, y2: yInt + this.perpSlope });
}
output.setTo(x, y, pt.x, pt.y);
return output;
}
/**
* Get a string representation of the line.
* @method toString
* @return {String}
* @public
*/
public toString(): string {
return "[{Line (x1=" + this.x1 + " y1=" + this.y1 + " x2=" + this.x2 + " y2=" + this.y2 + ")}]";
}
}
}
