### Joysticks and javascript (fruit on the bottom)

Of course, my goals were so much more humble–I just wanted something like the joystick. Since, as Martin Luther points out, “It is easier to tear down than to build,” I decided to make a stripped-down Javascript object that would do what I wanted. I thought I’d share it with you.

Please note that any infelicities in the following Javascript code derive in no way from Mr. DuBois. Honest.

You’ll need to save the following source code with a name like “basic_joystick.js” and then load it using the Max **jsui** object. There are eight individual outputs, corresponding to the 8 dots around the border of the circle. Positioning the red joystick within the circle will simultaneously output eight control values in the range 0. – 1.0 (perfect for, say, sending parameter messages to things hosted by the Max **vst~** object. The rest is up to you.

*_begin javascript*__

*/ joystick.js
/*

*/ cool joystick with multiple axis outputs*

/

/

*/ vastly simplified from gregory and luke’s 6.04 cadillac panner*

/props to Luke, at the very least. May good karma attend him!

/

*/ 8 outlets
inlets = 0;
outlets = 8;*

*/* global variables

var xpos = 0.;

var ypos = 0.5;

*/ initialize the arrays
var amps = new Array(8);
for(i=0;i<8;i++)
{
amps[i] = 0.0;
}*

*/* set up jsui defaults to 3d

sketch.default3d();

*/ initialize graphics
function loadbang()
{
doit(xpos, ypos);
draw();
refresh();
}*

*/* draw — main graphics function

function draw()

{

with (sketch)

{

*/ set how the polygons are rendered
glclearcolor(0.,0.,0.,0.); /* set the clear color

glclear();

*/ erase the background*

* glcullface(“back”); *

* /* draw background

glcolor(0.,0.,0.,0.);

moveto(0.,0., -0.2); */ move the drawing point
shapeslice(10);
sphere(0.04);
glcolor(1., 1., 1., 1.);
shapeslice(60);
circle(1.0);*

* /* dots around the outside (crufty, but hey)

moveto(-1.,0., -0.1); */ move the drawing point
glcolor(1.,1.,1.,1.);
shapeslice(10);
sphere(0.04);
moveto(1.,0., -0.1); /* move the drawing point

sphere(0.04);

moveto(0.,1., -0.1);

*/ move the drawing point*

sphere(0.04);

moveto(0.,-1., -0.1); /move the drawing point

sphere(0.04);

moveto(0.,-1., -0.1); /

sphere(0.04);

moveto(-.707107,.707107, -0.1);

*/ move the drawing point*

sphere(0.04);

moveto(.707107,.707107, -0.1); /move the drawing point

sphere(0.04);

moveto(.707107,.707107, -0.1); /

sphere(0.04);

moveto(.707107,-.707107, -0.1);

*/ move the drawing point*

sphere(0.04);

moveto(-.707107,-.707107, -0.1); /move the drawing point

sphere(0.04);

moveto(-.707107,-.707107, -0.1); /

sphere(0.04);

shapeslice(10);

*/ Here’s the “tip” of the joystick
glcolor(.75,0.,.0,1.);
glclear(“depth”); /* erase depth buffer

shapeslice(20);

moveto(xpos, ypos, -0.1);

sphere(0.08);

}

}

*/ bang — draw and refresh display
function bang()
{
draw();
refresh();
}*

*/* onresize — deal with a resized jsui box

function onresize(w,h)

{

bang(); */ draw and refresh display
}
onresize.local = 1; /* make function private to prevent triggering from Max

function doit(x,y)

{

xsquare = Math.pow(x, 2);

ysquare = Math.pow(y, 2)

dist = Math.sqrt(xsquare+ysquare);

if(dist>1.000)

{

dist = 1.000;

}

theta = Math.atan2(y, x);

mathpi = Math.PI*0.25;

xpos = dist*Math.cos(theta);

ypos = dist*Math.sin(theta);

xpos1 = dist*Math.cos(theta-mathpi);

ypos1 = dist*Math.sin(theta-mathpi);

if (xpos>1.0) xpos=1.0;

if (ypos>1.0) ypos=1.0;

if (xpos1>1.0) xpos1=1.0;

if (ypos1>1.0) ypos1=1.0;

amps[0] = (ypos+1.0)*0.5;

amps[1] = (xpos1+1.0)*0.5;

amps[2] = (xpos+1.0)*0.5;

amps[3] = 1.0-(ypos1+1.0)*0.5;

amps[4] = 1.0-amps[0];

amps[5] = 1.0-amps[1];

amps[6] = 1.0-amps[2];

amps[7] = 1.0-amps[3];

for(i=0;i<8;i++)

{

outlet(i, amps[i]);

}

}

doit.local = 1;

*/ onclick — deal with mouse click event
function onclick(x,y)
{
doit(sketch.screentoworld(x,y)[0], sketch.screentoworld(x,y)[1]);*

* bang(); /* draw and refresh display

}

onclick.local = 1; */ make function private to prevent triggering from Max*

*function ondrag(x,y)
{
doit(sketch.screentoworld(x,y)[0], sketch.screentoworld(x,y)[1]);*

* bang(); /* draw and refresh display

}

ondrag.local = 1; */ make function private to prevent triggering from Max*

*/* ondblclick — pass buck to onclick()

function ondblclick(x,y)

{

doit(sketch.screentoworld(x,y)[0], sketch.screentoworld(x,y)[1]);

bang(); */ draw and refresh display
}
ondblclick.local = 1; /* make function private to prevent triggering from Max

function fsaa(v)

{

sketch.fsaa = v;

bang();

}

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