The Dynamic Duo - Parabola Object

Parabola Object

parabola

The Parabola Object will slide the layer along a parabolic path.

Initialization:

objectName.parabola = new Circle(objectName,"parabola")

Example:

mylayer = new DynLayer("mylayerDiv")
mylayer.parabola = new Parabola(mylayer,"parabola")

The play() Method:

The play() method begins the parabola:

objectName.parabola.play(type,distx,disty,xinc,speed,fn)

type - 1 is a dropping parabola, 2 is an arcing parabola
distx - horizontal distance
disty - vertical distance
xinc - the number of pixels to move horizontally each repetition
speed - speed of repetition
fn - (optional) function or statement to execute when complete

Examples:

mylayer.parabola.play(1,200,200,5,20)

The stop() Methods:

Work the same as in the circle() method. I didn't bother with a pause method cause I can't see it being useful.

objectName.sinewave.stop()

Source Code:

// Parabola Object
// Copyright 1998 Dan Steinman
// Available at the Dynamic Duo (http://www.dansteinman.com/dynduo/)
// June 22, 1998.
// In order to use this code you must keep this disclaimer

function Parabola(dynlayer,name) {
	this.dynlayer = dynlayer.obj
	this.name = name
	this.play = ParabolaPlay
	this.slide = ParabolaSlide
	this.stop = ParabolaStop
}
function ParabolaPlay(type,distx,disty,xinc,speed,fn) {
	if (!this.active) {
		this.type = type
		this.distx = Math.abs(distx)
		this.disty = Math.abs(disty)
		this.dirx = (distx>0)? 1:-1
		this.diry = (disty>0)? 1:-1
		this.xinc = xinc
		this.speed = speed
		this.fn = fn
		this.startX = eval(this.dynlayer+'.x')
		this.startY = eval(this.dynlayer+'.y')
		this.active = false
		this.i = 0
		this.factor = this.disty/Math.pow(this.distx/this.type,2)
		this.active = true
		eval(this.dynlayer+'.'+this.name+'.slide()')
	}
}
function ParabolaSlide() {
	if (this.active && Math.abs(this.i)<this.distx) {
		this.i += this.dirx*this.xinc
		var x = this.startX + this.i
		if (this.type==1) var y = this.startY + this.diry*this.factor*Math.pow(Math.abs(this.i),2)
		if (this.type==2) var y = this.startY + this.diry*this.factor*Math.pow(this.distx/2-Math.abs(this.i),2) + this.diry*this.disty
		eval(this.dynlayer+'.moveTo('+x+','+y+')')
		setTimeout(this.dynlayer+'.'+this.name+'.slide()',this.speed)
	}
	else {
		this.active = false
		eval(this.fn)
	}
}
function ParabolaStop() {
	this.active = false
}

Demo:

View parabola1.html for a parabola demo.

Geometric Objects