gear

gear.cadjs

function sqrt(a){
  return Math.pow(a,0.5);
}

function sq(a){
  return Math.pow(a,2);
}

function rotate(theta, func){
  return function(x,y){
    var xprime = Math.cos(theta)*x-Math.sin(theta)*y;
    var yprime = Math.sin(theta)*x+Math.cos(theta)*y;

    return func(xprime,yprime);
  }
}

function translate(tx, ty, func){
  return function(x,y){
    var xprime = x-tx;
    var yprime = y-ty;

    return func(xprime,yprime);
  }
}

function reflect_y(func){
  return function(x,y){
    return func(x,-y);
  }
}

function intersect(funcs){
  var metaargs=arguments;
  return function(x,y) {
    var ret=true;
    for(var i=0; i<metaargs.length;i++){
      ret = ret && metaargs[i](x,y);
    }
    return ret;
  }
}

function union(funcs){
  var metaargs=arguments;
  return function(x,y) {
    var ret=false;
    for(var i=0; i<metaargs.length;i++){
      ret = ret || metaargs[i](x,y);
    }
    return ret;
  }
}

function pie_slice(top,bottom){
  return function(x,y){
    return atan2(y, x)<=top && atan2(y, x)>=bottom;
  }
}

var atan = Math.atan;
var acos = Math.acos;
var cos = Math.cos;
var sin = Math.sin;
var atan2 = Math.atan2;
var pi = Math.PI;

var border = 0.05 ;

var outer_diameter = 0.65 ;
var base_diameter = outer_diameter * 0.88 ;
var root_diameter = outer_diameter * 0.82 ;
var pitch_diameter = outer_diameter * 0.92 ;
var num_teeth = 24 ;

var outer_radius = outer_diameter/2;
var base_radius = base_diameter/2;
var root_radius = root_diameter/2;
var pitch_radius = pitch_diameter/2;

function maketooth(base_radius){
  // Formula for the region on the upper left of an involute
  // (thanks to Peter Fedak, HMC 2013)

  return function(x,y){
    return (base_radius*(atan(y/x) + acos(base_radius/sqrt(x*x + y*y))) - sqrt((x*x + y*y)-base_radius*base_radius)) < 0;
  }
}

// Calculate how to rotate the tooth for the given pitch diameter
var pitch_param = sqrt(sq(pitch_radius) / sq(base_radius) - 1.0)
var x_pitch = base_radius * (cos(pitch_param) + pitch_param * sin(pitch_param))
var y_pitch = base_radius * (sin(pitch_param) - pitch_param * cos(pitch_param))
var pitch_angle = atan2(y_pitch, x_pitch)
var rotation_angle = 90. / num_teeth - pitch_angle * 180 / pi

tooth = maketooth(30);
tooth = rotate(rotation_angle, tooth);
tooth = intersect( tooth, reflect_y(tooth) );

return true;

//return true;

//tooth = union(tooth, pie_slice(1,-1));
//return true;
//return translate( 150,150, tooth )(x,y);
//return translate(150,150,pie_slice(rotation_angle,-pi/3))(x,y);