Elliptical Motion

programming flash
1

Finally basic trig stuff is starting to make sense to me…after going through the excellent carousel tutorial on http://www.gotoandlearn.com/download.php i really understand the basics of using a radiusX, radiusY, centreX and centreY coupled with and angle and cos for _x, sin for _y - its all so clear now…

but - if i use this method to animate anything, the motion naturally slows down as it approaches the tighter ends of the ellipse…obviously if i set the radiusX and radiusY to identical values, the speed will be uniform…but i was wondering:

is there a way to move objects in an elliptical fashion while keeping a constant speed, no matter the dimensions of the ellipse or the radius difference?

in case anyone was wondering, heres the current code im using to move stuff - based around incrementing the value of the variable “angle”


t.onEnterFrame = function():Void  {
        this._x = this.radiusX*(Math.cos(this.angle))+this.centreX;
        this._y = (this.radiusY*(Math.sin(this.angle)))+this.centreY;
        this.angle -= 0.035;
}