// Hi! This 3D model was built using the <canvas> 2D drawing API.
// I'm working on a library to make these sort of 3D illustrations,
// But it's not ready for prime-time. Stay tuned! *~ dd ~*

// -------------------------- utils -------------------------- //

var TAU = Math.PI * 2;

function extend( a, b ) {
  for ( var prop in b ) {
    a[ prop ] = b[ prop ];
  }
  return a;
}

function lerp( a, b, t ) {
  return ( b - a ) * t + a;
}

function modulo( num, div ) {
  return ( ( num % div ) + div ) % div;
}

// -------------------------- Vector3 -------------------------- //

function Vector3( position ) {
  this.set( position );
}

Vector3.prototype.set = function( pos ) {
  pos = Vector3.sanitize( pos );
  this.x = pos.x;
  this.y = pos.y;
  this.z = pos.z;
  return this;
};

Vector3.prototype.rotate = function( rotation ) {
  if ( !rotation ) {
    return;
  }
  this.rotateZ( rotation.z );
  this.rotateY( rotation.y );
  this.rotateX( rotation.x );
  return this;
};

Vector3.prototype.rotateZ = function( angle ) {
  rotateProperty( this, angle, 'x', 'y' );
};

Vector3.prototype.rotateX = function( angle ) {
  rotateProperty( this, angle, 'y', 'z' );
};

Vector3.prototype.rotateY = function( angle ) {
  rotateProperty( this, angle, 'x', 'z' );
};

function rotateProperty( vec, angle, propA, propB ) {
  if ( angle % TAU === 0 ) {
    return;
  }
  var cos = Math.cos( angle );
  var sin = Math.sin( angle );
  var a = vec[ propA ];
  var b = vec[ propB ];
  vec[ propA ] = a*cos - b*sin;
  vec[ propB ] = b*cos + a*sin;
}

Vector3.prototype.add = function( vec ) {
  if ( !vec ) {
    return;
  }
  vec = Vector3.sanitize( vec );
  this.x += vec.x;
  this.y += vec.y;
  this.z += vec.z;
  return this;
};

Vector3.prototype.subtract = function( vec ) {
  if ( !vec ) {
    return;
  }
  vec = Vector3.sanitize( vec );
  this.x -= vec.x;
  this.y -= vec.y;
  this.z -= vec.z;
  return this;
};

Vector3.prototype.multiply = function( vec ) {
  if ( !vec ) {
    return;
  }
  vec = Vector3.sanitize( vec );
  this.x *= vec.x;
  this.y *= vec.y;
  this.z *= vec.z;
  return this;
};

Vector3.prototype.transform = function( translation, rotation, scale ) {
  this.multiply( scale );
  this.rotate( rotation );
  this.add( translation );
};

Vector3.prototype.lerp = function( vec, t ) {
  this.x = lerp( this.x, vec.x, t );
  this.y = lerp( this.y, vec.y, t );
  this.z = lerp( this.z, vec.z, t );
  return this;
};

// ----- utils ----- //

// add missing properties
Vector3.sanitize = function( vec ) {
  vec = vec || {};
  vec.x = vec.x || 0;
  vec.y = vec.y || 0;
  vec.z = vec.z || 0;
  return vec;
};

// -------------------------- Anchor -------------------------- //

function Anchor( options ) {
  this.create( options );
}

Anchor.prototype.create = function( options ) {
  // set defaults & options
  extend( this, this.constructor.defaults );
  options = options || {};
  this.setOptions( this, options );

  // transform
  this.translate = new Vector3( options.translate );
  this.rotate = new Vector3( options.rotate );
  var scale = extend( { x: 1, y: 1, z: 1 }, options.scale );
  this.scale = new Vector3( scale );
  // origin
  this.origin = new Vector3();
  this.renderOrigin = new Vector3();
  // children
  this.children = [];
  if ( this.addTo ) {
    this.addTo.addChild( this );
  }
};

Anchor.defaults = {};

Anchor.optionKeys = Object.keys( Anchor.defaults ).concat([
  'rotate',
  'translate',
  'scale',
  'addTo',
]);

Anchor.prototype.setOptions = function( item, options ) {
  var optionKeys = this.constructor.optionKeys;

  for ( var key in options ) {
    if ( optionKeys.includes( key ) ) {
      item[ key ] = options[ key ];
    }
  }
};

Anchor.prototype.addChild = function( shape ) {
  this.children.push( shape );
};

// ----- update ----- //

Anchor.prototype.update = function() {
  // update self
  this.reset();
  // update children
  this.children.forEach( function( child ) {
    child.update();
  });
  this.transform( this.translate, this.rotate, this.scale );
};

Anchor.prototype.reset = function() {
  this.renderOrigin.set( this.origin );
};

Anchor.prototype.transform = function( translation, rotation, scale ) {
  this.renderOrigin.transform( translation, rotation, scale );
  // transform children
  this.children.forEach( function( child ) {
    child.transform( translation, rotation, scale );
  });
};


Anchor.prototype.updateGraph = function() {
  this.update();
  this.checkFlatGraph();
  this.flatGraph.forEach( function( item ) {
    item.updateSortValue();
  });
  // z-sort
  this.flatGraph.sort( sortBySortValue );
};

function sortBySortValue( a, b ) {
  return b.sortValue - a.sortValue;
}

Anchor.prototype.checkFlatGraph = function() {
  if ( !this.flatGraph ) {
    this.updateFlatGraph();
  }
};

Anchor.prototype.updateFlatGraph = function() {
  this.flatGraph = this.getFlatGraph();
};

// return Array of self & all child graph items
Anchor.prototype.getFlatGraph = function() {
  var flatGraph = [ this ];
  this.children.forEach( function( child ) {
    var childFlatGraph = child.getFlatGraph();
    flatGraph = flatGraph.concat( childFlatGraph );
  });
  return flatGraph;
};

Anchor.prototype.updateSortValue = function() {
  this.sortValue = this.renderOrigin.z;
};

// ----- render ----- //

Anchor.prototype.render = function() {};

Anchor.prototype.renderGraph = function( ctx ) {
  this.checkFlatGraph();
  this.flatGraph.forEach( function( item ) {
    item.render( ctx );
  });
};

// ----- misc ----- //

Anchor.prototype.copy = function( options ) {
  // copy options
  var itemOptions = {};
  var optionKeys = this.constructor.optionKeys;
  optionKeys.forEach( function( key ) {
    itemOptions[ key ] = this[ key ];
  }, this );
  // add set options
  this.setOptions( itemOptions, options );
  var ItemClass = this.constructor;
  return new ItemClass( itemOptions );
};

Anchor.prototype.normalizeRotate = function() {
  this.rotate.x = modulo( this.rotate.x, TAU );
  this.rotate.y = modulo( this.rotate.y, TAU );
  this.rotate.z = modulo( this.rotate.z, TAU );
};

// ----- subclass ----- //

function getSubclass( Super ) {
  return function( defaults ) {
    // create constructor
    function Item( options ) {
      this.create( options );
    }

    Item.prototype = Object.create( Super.prototype );
    Item.prototype.constructor = Item;

    Item.defaults = extend( {}, Super.defaults );
    Item.defaults = extend( Item.defaults, defaults );
    Item.optionKeys = Super.optionKeys.slice(0)
      .concat( Object.keys( Item.defaults ) );
    Item.subclass = getSubclass( Item );

    return Item;
  };
}

Anchor.subclass = getSubclass( Anchor );


// -------------------------- PathAction -------------------------- //

function PathAction( method, points, previousPoint ) {
  this.method = method;
  this.points = points.map( mapVectorPoint );
  this.renderPoints = points.map( mapVectorPoint );
  this.previousPoint = previousPoint;
  this.endRenderPoint = this.renderPoints[ this.renderPoints.length - 1 ];
  // arc actions come with previous point & corner point
  // but require bezier control points
  if ( method == 'arc' ) {
    this.controlPoints = [ new Vector3(), new Vector3() ];
  }
}

function mapVectorPoint( point ) {
  return new Vector3( point );
}

PathAction.prototype.reset = function() {
  // reset renderPoints back to orignal points position
  var points = this.points;
  this.renderPoints.forEach( function( renderPoint, i ) {
    var point = points[i];
    renderPoint.set( point );
  });
};

PathAction.prototype.transform = function( translation, rotation, scale ) {
  this.renderPoints.forEach( function( renderPoint ) {
    renderPoint.transform( translation, rotation, scale );
  });
};

PathAction.prototype.render = function( ctx ) {
  this[ this.method ]( ctx );
};

PathAction.prototype.move = function( ctx ) {
  var point = this.renderPoints[0];
  ctx.moveTo( point.x, point.y );
};

PathAction.prototype.line = function( ctx ) {
  var point = this.renderPoints[0];
  ctx.lineTo( point.x, point.y );
};

PathAction.prototype.bezier = function( ctx ) {
  var cp0 = this.renderPoints[0];
  var cp1 = this.renderPoints[1];
  var end = this.renderPoints[2];
  ctx.bezierCurveTo( cp0.x, cp0.y, cp1.x, cp1.y, end.x, end.y );
};

PathAction.prototype.arc = function( ctx ) {
  var prev = this.previousPoint;
  var corner = this.renderPoints[0];
  var end = this.renderPoints[1];
  var cp0 = this.controlPoints[0];
  var cp1 = this.controlPoints[1];
  cp0.set( prev ).lerp( corner, 9/16 );
  cp1.set( end ).lerp( corner, 9/16 );
  ctx.bezierCurveTo( cp0.x, cp0.y, cp1.x, cp1.y, end.x, end.y );
};

// -------------------------- Shape -------------------------- //

var Shape = Anchor.subclass({
  stroke: true,
  fill: false,
  color: 'black',
  lineWidth: 1,
  closed: true,
  rendering: true,
  path: [ {} ],
  front: { z: -1 },
});

var protoCreate = Anchor.prototype.create;

Shape.prototype.create = function( options ) {
  Anchor.prototype.create.call( this, options );
  this.updatePath(); // hook for Rect, Ellipse, & other subclasses
  this.updatePathActions();

  // front
  this.front = new Vector3( options.front || this.front );
  this.renderFront = new Vector3( this.front );
  this.renderNormal = new Vector3();
};

var defaultShapeKeys = Object.keys( Shape.defaults );
Shape.optionKeys = Shape.optionKeys.concat( defaultShapeKeys ).concat([
  'width',
  'height',
  'front',
  'backfaceHidden',
]);

var actionNames = [
  'move',
  'line',
  'bezier',
  'arc',
];

Shape.prototype.updatePath = function() {};

// parse path into PathActions
Shape.prototype.updatePathActions = function() {
  var previousPoint;
  this.pathActions = this.path.map( function( pathPart, i ) {
    // pathPart can be just vector coordinates -> { x, y, z }
    // or path instruction -> { arc: [ {x0,y0,z0}, {x1,y1,z1} ] }
    var keys = Object.keys( pathPart );
    var method = keys[0];
    var points = pathPart[ method ];
    var isInstruction = keys.length === 1 && actionNames.includes( method ) &&
      Array.isArray( points );

    if ( !isInstruction ) {
      method = 'line';
      points = [ pathPart ];
    }

    // first action is always move
    method = i === 0 ? 'move' : method;
    // arcs require previous last point
    var pathAction = new PathAction( method, points, previousPoint );
    // update previousLastPoint
    previousPoint = pathAction.endRenderPoint;
    return pathAction;
  });
};

// ----- update ----- //

Shape.prototype.reset = function() {
  this.renderOrigin.set( this.origin );
  this.renderFront.set( this.front );
  // reset pathAction render points
  this.pathActions.forEach( function( pathAction ) {
    pathAction.reset();
  });
};

Shape.prototype.transform = function( translation, rotation, scale ) {
  // TODO, only transform these if backfaceHidden for perf?
  this.renderOrigin.transform( translation, rotation, scale );
  this.renderFront.transform( translation, rotation, scale );
  this.renderNormal.set( this.renderOrigin ).subtract( this.renderFront );
  // transform points
  this.pathActions.forEach( function( pathAction ) {
    pathAction.transform( translation, rotation, scale );
  });
  // transform children
  this.children.forEach( function( child ) {
    child.transform( translation, rotation, scale );
  });
};


Shape.prototype.updateSortValue = function() {
  var sortValueTotal = 0;
  this.pathActions.forEach( function( pathAction ) {
    sortValueTotal += pathAction.endRenderPoint.z;
  });
  // average sort value of all points
  // def not geometrically correct, but works for me
  this.sortValue = sortValueTotal / this.pathActions.length;
};

// ----- render ----- //

Shape.prototype.render = function( ctx ) {
  var length = this.pathActions.length;
  if ( !this.rendering || !length ) {
    return;
  }
  // hide backface
  var isFacingBack = this.renderNormal.z > 0;
  if ( this.backfaceHidden && isFacingBack ) {
    return;
  }
  // render dot or path
  var isDot = length == 1;
  if ( isDot ) {
    this.renderDot( ctx );
  } else {
    this.renderPath( ctx );
  }
};

// Safari does not render lines with no size, have to render circle instead
Shape.prototype.renderDot = function( ctx ) {
  ctx.fillStyle = this.color;
  var point = this.pathActions[0].endRenderPoint;
  ctx.beginPath();
  var radius = this.lineWidth/2;
  ctx.arc( point.x, point.y, radius, 0, TAU );
  ctx.fill();
};

Shape.prototype.renderPath = function( ctx ) {
  // set render properties
  ctx.fillStyle = this.color;
  ctx.strokeStyle = this.color;
  ctx.lineWidth = this.lineWidth;

  // render points
  ctx.beginPath();
  this.pathActions.forEach( function( pathAction ) {
    pathAction.render( ctx );
  });
  var isTwoPoints = this.pathActions.length == 2 &&
    this.pathActions[1].method == 'line';
  if ( !isTwoPoints && this.closed ) {
    ctx.closePath();
  }
  if ( this.stroke ) {
    ctx.stroke();
  }
  if ( this.fill ) {
    ctx.fill();
  }
};

// -------------------------- Ellipse -------------------------- //

var Ellipse = Shape.subclass({
  width: 1,
  height: 1,
  closed: false,
});

Ellipse.prototype.updatePath = function() {
  var x = this.width / 2;
  var y = this.height / 2;
  this.path = [
    { x: 0, y: -y },
    { arc: [ // top right
      { x: x, y: -y },
      { x: x, y: 0 },
    ]},
    { arc: [ // bottom right
      { x: x, y: y },
      { x: 0, y: y },
    ]},
    { arc: [ // bottom left
      { x: -x, y: y },
      { x: -x, y: 0 },
    ]},
    { arc: [ // bottom left
      { x: -x, y: -y },
      { x: 0, y: -y },
    ]},
  ];
};

// -------------------------- Group -------------------------- //

var Group = Anchor.subclass({
  updateSort: false,
});

// ----- update ----- //

Group.prototype.updateSortValue = function() {
  var sortValueTotal = 0;
  this.checkFlatGraph();
  this.flatGraph.forEach( function( item ) {
    item.updateSortValue();
    sortValueTotal += item.sortValue;
  });
  // average sort value of all points
  // def not geometrically correct, but works for me
  this.sortValue = sortValueTotal / this.flatGraph.length;

  if ( this.updateSort ) {
    this.flatGraph.sort( function( a, b ) {
      return b.sortValue - a.sortValue;
    });
  }
};

// ----- render ----- //

Group.prototype.render = function( ctx ) {
  this.checkFlatGraph();
  this.flatGraph.forEach( function( item ) {
    item.render( ctx );
  });
};

// do not include children, group handles rendering & sorting internally
Group.prototype.getFlatGraph = function() {
  return [ this ];
};


Group.prototype.checkFlatGraph = function() {
  if ( !this.flatGraph ) {
    this.updateFlatGraph();
  }
};

Group.prototype.updateFlatGraph = function() {
  this.flatGraph = this.getChildFlatGraph();
};

// get flat graph only used for group
// do not include in parent flatGraphs
Group.prototype.getChildFlatGraph = function() {
  // do not include self
  var flatGraph = [];
  this.children.forEach( function( child ) {
    var childFlatGraph = child.getFlatGraph();
    flatGraph = flatGraph.concat( childFlatGraph );
  });
  return flatGraph;
};

// -------------------------- Dragger -------------------------- //

// quick & dirty drag event stuff
// messes up if multiple pointers/touches

// event support, default to mouse events
var downEvent = 'mousedown';
var moveEvent = 'mousemove';
var upEvent = 'mouseup';
if ( window.PointerEvent ) {
  // PointerEvent, Chrome
  downEvent = 'pointerdown';
  moveEvent = 'pointermove';
  upEvent = 'pointerup';
} else if ( 'ontouchstart' in window ) {
  // Touch Events, iOS Safari
  downEvent = 'touchstart';
  moveEvent = 'touchmove';
  upEvent = 'touchend';
}

function noop() {}

function Dragger( options ) {
  this.startElement = options.startElement;
  this.onPointerDown = options.onPointerDown || noop;
  this.onPointerMove = options.onPointerMove || noop;
  this.onPointerUp = options.onPointerUp || noop;
  
  this.startElement.addEventListener( downEvent, this );
}

Dragger.prototype.handleEvent = function( event ) {
  var method = this[ 'on' + event.type ];
  if ( method ) {
    method.call( this, event );
  }
};

Dragger.prototype.onmousedown =
Dragger.prototype.onpointerdown = function( event ) {
  this.pointerDown( event, event );
};

Dragger.prototype.ontouchstart = function( event ) {
  this.pointerDown( event, event.changedTouches[0] );
};

Dragger.prototype.pointerDown = function( event, pointer ) {
  event.preventDefault();
  this.dragStartX = pointer.pageX;
  this.dragStartY = pointer.pageY;
  window.addEventListener( moveEvent, this );
  window.addEventListener( upEvent, this );
  this.onPointerDown( pointer );
};

Dragger.prototype.ontouchmove = function( event ) {
  // HACK, moved touch may not be first
  this.pointerMove( event, event.changedTouches[0] );
};

Dragger.prototype.onmousemove =
Dragger.prototype.onpointermove = function( event ) {
  this.pointerMove( event, event );
};

Dragger.prototype.pointerMove = function( event, pointer ) {
  event.preventDefault();
  var moveX = pointer.pageX - this.dragStartX;
  var moveY = pointer.pageY - this.dragStartY;
  this.onPointerMove( pointer, moveX, moveY );
};

Dragger.prototype.onmouseup = 
Dragger.prototype.onpointerup =
Dragger.prototype.ontouchend =
Dragger.prototype.pointerUp = function( event ) {
  window.removeEventListener( moveEvent, this );
  window.removeEventListener( upEvent, this );
  this.onPointerUp( event );
};

// -------------------------- hemisphere -------------------------- //

function hemisphere( options ) {
  var group = new Group({
    addTo: options.addTo,
    rotate: options.rotate,
    translate: options.translate,
    scale: options.scale,
  });

  // inside face
  var face = new Ellipse({
    width: options.size,
    height: options.size,
    addTo: group,
    color: options.insideColor || options.color,
    lineWidth: options.lineWidth,
    stroke: options.stroke,
    fill: options.fill,
    backfaceHidden: true,
  });
  // outside face
  var outsideColor = options.outsideColor || options.color;
  face.copy({
    color: options.outsideColor || options.color,
    rotate: { y: TAU/2 },
  });

  // ----- dome ----- //

  group.render = function( ctx ) {
    // render dome
    var contourAngle = Math.atan2( face.renderNormal.y, face.renderNormal.x );
    var startAngle = contourAngle + TAU/4;
    var endAngle = contourAngle - TAU/4;

    ctx.strokeStyle = ctx.fillStyle = outsideColor;
    ctx.lineWidth = options.lineWidth;
    ctx.beginPath();
    var x = group.renderOrigin.x;
    var y = group.renderOrigin.y;
    ctx.arc( x, y, options.size/2, startAngle, endAngle );
    ctx.closePath();
    if ( options.stroke ) {
      ctx.stroke();
    }
    if ( options.fill ) {
      ctx.fill();
    }

    Group.prototype.render.call( this, ctx );
  };
}

// -------------------------- demo -------------------------- //

var canvas = document.querySelector('canvas');
var ctx = canvas.getContext('2d');
var w = 48;
var h = 48;
var minWindowSize = Math.min( window.innerWidth, window.innerHeight );
var zoom = Math.min( 10, Math.floor( minWindowSize / w ) );
var pixelRatio = window.devicePixelRatio || 1;
zoom *= pixelRatio;
var canvasWidth = canvas.width = w * zoom;
var canvasHeight = canvas.height = h * zoom;
// set canvas screen size
if ( pixelRatio > 1 ) {
  canvas.style.width = canvasWidth / pixelRatio + 'px';
  canvas.style.height = canvasHeight / pixelRatio + 'px';
}

var isRotating = true;
var t = 0;
var cycleFrame = 360;
// colors
var yellow = '#ED0';
var gold = '#EA0';
var orange = '#E62';
var magenta = '#C25';
var navy = '#249';

// -- illustration shapes --- //

var scene = new Anchor();

// -----  ----- //


hemisphere({
  size: 13,
  addTo: scene,
  translate: { y: 16 },
  rotate: { x: -TAU/4 },
  insideColor: navy,
  outsideColor: magenta,
  stroke: false,
  fill: true,
});
hemisphere({
  size: 13,
  addTo: scene,
  translate: { y: -16 },
  rotate: { x: TAU/4 },
  insideColor: navy,
  outsideColor: magenta,
  stroke: false,
  fill: true,
});

var colorWheel = [ navy, magenta, orange, gold, yellow, ];

[ -1, 1 ].forEach( function( ySide ) {
  for ( var i=0; i < 5; i++ ) {
    var rotor1 = new Anchor({
      addTo: scene,
      rotate: { y: TAU/5 * i },
    });
    var rotor2 = new Anchor({
      addTo: rotor1,
      rotate: { x: TAU/6 },
    });

    hemisphere({
      size: 13,
      addTo: rotor2,
      translate: { y: -16*ySide },
      rotate: { x: TAU/4*ySide },
      outsideColor: colorWheel[i],
      insideColor: colorWheel[ (i+7) % 5 ],
      stroke: false,
      fill: true,
    });
  }
});

// -- animate --- //

function easeInOut( i ) {
  var isFirstHalf = i < 0.5;
  var i1 = isFirstHalf ? i : 1 - i;
  i1 = i1 / 0.5;
  // make easing steeper with more multiples
  var i2 = i1 * i1 * i1;
  i2 = i2 / 2;
  return isFirstHalf ? i2 : i2*-1 + 1;
}

function animate() {
  update();
  render();
  requestAnimationFrame( animate );
}

animate();

// -- update -- //

function update() {
  if ( isRotating ) {
    t += 1/cycleFrame;
    t = t % 1;
    var isFirstHalf = t < 0.5;
    var halfT = isFirstHalf ? t : t - 0.5;
    var doubleEaseT = easeInOut( halfT * 2 ) / 2;
    doubleEaseT += isFirstHalf ? 0 : 0.5;
    scene.rotate.y = doubleEaseT * TAU;
    scene.rotate.x = Math.cos( doubleEaseT * TAU ) * TAU/12;
  }

  scene.updateGraph();
}

// -- render -- //

ctx.lineCap = 'round';
ctx.lineJoin = 'round';

function render() {
  ctx.clearRect( 0, 0, canvasWidth, canvasHeight );

  ctx.save();
  ctx.scale( zoom, zoom );
  ctx.translate( w/2, h/2 );

  scene.renderGraph( ctx );

  ctx.restore();
}

// ----- inputs ----- //

// click drag to rotate
var dragStartAngleX, dragStartAngleY;

new Dragger({
  startElement: canvas,
  onPointerDown: function() {
    isRotating = false;
    dragStartAngleX = scene.rotate.x;
    dragStartAngleY = scene.rotate.y;
  },
  onPointerMove: function( pointer, moveX, moveY ) {
    var angleXMove = moveY / canvasWidth * TAU;
    var angleYMove = moveX / canvasWidth * TAU;
    scene.rotate.x = dragStartAngleX + angleXMove;
    scene.rotate.y = dragStartAngleY + angleYMove;
  },
});