I've been messing with mapping of a 3d object onto the trajectory of

jit.boids3d object. Obviously mapping object to the right position is

trivial. However, even though I am calculating angles using old xyz vs. new

xyz and then calculating actual angles using atan, something fishy is going

The algorithm for parsing data out is contained within javascript file which

    zrot=-Math.atan(xvec/yvec)/PI*180-90;

            zrot = 180 - zrot;

            zrot = 180 + zrot;

    yrot=Math.atan(xvec/zvec)/PI*180-90;

            yrot = 180 + yrot;

    xrot=Math.atan(yvec/zvec)/PI*180+90;

            xrot = 180 - xrot;

    var tmp = arrayfromargs(arguments);

        post ("zrot says: Invalid number of arguments (9

Now, some of these had to be for some reason adjusted manually (namely four

quadrants of a circle and their behavior using atan()). Why? I have no idea.

At any rate, I was wondering whether there is a more "elegant" way to

achieve the same without delving into javascript. If not, I would greatly

appreciate some help at deciphering this odd behavior.

Composition, Music Technology, CCTAD, CHCI

http://www.music.vt.edu/people/faculty/bukvic/

I've been messing with mapping of a 3d object onto the trajectory of
jit.boids3d object. Obviously mapping object to the right position is
trivial. However, even though I am calculating angles using old xyz vs. new
xyz and then calculating actual angles using atan, something fishy is going
on.

The algorithm for parsing data out is contained within javascript file which
looks as follows:

function calculate()
{
	xvec=x2-x1;
	yvec=y2-y1;
	zvec=z2-z1;

	zrot=-Math.atan(xvec/yvec)/PI*180-90;
	if(yvec < 0) {
		if (xvec < 0) {
			//post("cn");
			zrot = 180 - zrot;
		}
		else {
			//post("dn");
			zrot = 180 + zrot;
		}
	}
	else if (xvec < 0) {
		//post("bn");
	}
	else {
		//post("an");
		zrot = -zrot;
	}

	yrot=Math.atan(xvec/zvec)/PI*180-90;
	if(zvec < 0) {
		if (xvec < 0) {
			//post("cn");
			yrot = 180 + yrot;
		}
		else {
			//post("dn");
			yrot = -yrot;
		}
	}
	else if (xvec < 0) {
		//post("bn");
	}
	else {
		//post("an");
		yrot = 180 - yrot;
	}

	xrot=Math.atan(yvec/zvec)/PI*180+90;
	if(zvec < 0) {
		if (yvec < 0) {
			//post("cn");
			xrot = 180 - xrot;
		}
		else {
			//post("dn");
			xrot = 180 - xrot;
		}
	}
	else if (yvec < 0) {
		//post("bn");
		xrot = 180 + xrot;
	}
	else {
		//post("an");
		xrot = -xrot;
	}

function output()
{
	outlet(5,zrot);
	outlet(4,yrot);
	outlet(3,xrot);
	outlet(2,z2);
	outlet(1,y2);
	outlet(0,x2);
}

Now, some of these had to be for some reason adjusted manually (namely four
quadrants of a circle and their behavior using atan()). Why? I have no idea.

At any rate, I was wondering whether there is a more "elegant" way to
achieve the same without delving into javascript. If not, I would greatly
appreciate some help at deciphering this odd behavior.

Ivica Ico Bukvic, D.M.A.
Composition, Music Technology, CCTAD, CHCI
Virginia Tech
Dept. of Music - 0240
Blacksburg, VA 24061
(540) 231-1137
(540) 231-5034 (fax)
ico@vt.edu
http://www.music.vt.edu/people/faculty/bukvic/
http://ico.bukvic.net


mapping 3d object onto jit.boids3d