RE : Re: Rotation around Arbitrary axis addition to DisplayObject3D

Hi all,

I couldnt find a better way to do this, so i went ahead and added it into my DisplayObject3D class.

It rotates any DisplayObject3D around another DisplayObject3D (including itself) on any give axis... it basically replaces rotation. ( i saw that there was some little hack-together people had to use to achieve the same effect).

Below is the addition to displayObect3D, link to an example, and usage.

====================================================
SOURCE
http://pixelmixer.mine.nu/papervision/main.as
http://pixelmixer.mine.nu/papervision/DisplayObject3D.as

====================================================
EXAMPLE
http://djsparks.iweb.bsu.edu/papervision/arbitraryRotation_example1.html

====================================================
CLASS ADDITION

/**
    * ________________________________________________________________________________________________
    * ------------------------------------ I N C O M P L E T E ---------------------------------------
    * ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
    * Rotates the displayObject around an arbitrary axis of a given displayObject.
    *
    * @param    angle:Number                    The angle to rotate;
    * @param     axis:Number3D                    The "axis" around which to rotate;
    * @param    targetObject:DisplayObject3D    The object to rotate around.
    */
    public function rotateArbitrary( angle:Number, axis:Number3D = null, targetObject:DisplayObject3D = null):void
    {
        if(!targetObject) targetObject = this;
        if(!axis) axis = new Number3D(1,0,0);
       
        var direction:Number3D = axis;
        var originPoint:Number3D = new Number3D(targetObject.x , targetObject.y, targetObject.z);
       
        var v:Number = Math.sqrt(direction.x*direction.x + direction.y*direction.y);
        var w:Number = Math.sqrt(v*v + direction.z*direction.z);
       
        var oF:Matrix3D = new Matrix3D([1,0,0,- originPoint.x,
                                       0,1,0,-originPoint.y,
                                       0,0,1,-originPoint.z,
                                       0,0,0,1]);
        var iF:Matrix3D = Matrix3D.inverse(oF);
       
        var oG:Matrix3D;
       
        if(v != 0)
        {
            oG = new Matrix3D([direction.x/v,direction.y/v,0,0,
                                           - direction.y/v,direction.x/v,0,0,
                                            0,0,1,0,
                                            0,0,0,1]);
        }
        else
        {
            oG = Matrix3D.IDENTITY ();
        }
       
        var iG:Matrix3D = Matrix3D.inverse(oG);
       
        var oH:Matrix3D = new Matrix3D([direction.z/w,0,-v/w,0,
                                        0,1,0,0,
                                        v/w,0, direction.z/w,0,
                                        0,0,0,1]);
        var iH:Matrix3D = Matrix3D.inverse(oH);
       
        var W:Matrix3D = new Matrix3D([Math.cos(angle),-Math.sin(angle),0,0,
                                       Math.sin(angle),Math.cos(angle),0,0,
                                       0,0,1,0,
                                       0,0,0,1]);
                                      
        var P:Matrix3D = Matrix3D.multiply (Matrix3D.multiply(Matrix3D.multiply(Matrix3D.multiply(Matrix3D.multiply(Matrix3D.multiply(iF,iG),iH),W),oH),oG),oF);
       
        this.transform.calculateMultiply( P ,transform );
       
        if( this._transformDirty ) updateTransform();
    }



=============================================================
USAGE

        moon.rotateArbitrary (.02, new Number3D(1,1,1), earth);
        earth.rotateArbitrary(.01, new Number3D(-1,1,1));
        camera.rotateArbitrary(.02, new Number3D(1,1,1), earth);
       
        camera.lookAt(earth);

--
Dustin Sparks _______________________________________________
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