3D小森林

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// Hi! This 3D model was built using the <canvas> 2D drawing API.
// It uses lineWidth to give the illusion of form.
// 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.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.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;
};

// -------------------------- 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.multiply( scale );
    renderPoint.rotate( rotation );
    renderPoint.add( translation );
  });
};

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

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

Shape.prototype.create = function( options ) {
  // default
  extend( this, Shape.defaults );
  // set options
  setOptions( this, options );

this.updatePathActions();

// 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 );
  // children
  this.children = [];
  if ( this.addTo ) {
    this.addTo.addChild( this );
  }
};

Shape.defaults = {
  stroke: true,
  fill: false,
  color: 'black',
  lineWidth: 1,
  closed: true,
  rendering: true,
  path: [ {} ],
};

var optionKeys = Object.keys( Shape.defaults ).concat([
  'rotate',
  'translate',
  'scale',
  'addTo',
  'width',
  'height',
]);

function setOptions( shape, options ) {
  for ( var key in options ) {
    if ( optionKeys.includes( key ) ) {
      shape[ key ] = options[ key ];
    }
  }
}

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

// 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;
  });
};

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

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

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

Shape.prototype.reset = function() {
  // reset pathAction render points
  this.pathActions.forEach( function( pathAction ) {
    pathAction.reset();
  });
};

Shape.prototype.transform = function( translation, rotation, scale ) {
  // 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;
  }
  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();
  }
};

// return Array of self & all child shapes
Shape.prototype.getShapes = function() {
  var shapes = [ this ];
  this.children.forEach( function( child ) {
    var childShapes = child.getShapes();
    shapes = shapes.concat( childShapes );
  });
  return shapes;
};

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

Shape.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 );
};

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

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

Group.prototype.create = function( options ) {
  // set options
  setGroupOptions( this, options );

// transform
  this.translate = Vector3.sanitize( this.translate );
  this.rotate = Vector3.sanitize( this.rotate );
  // children
  this.children = [];
  if ( this.addTo ) {
    this.addTo.addChild( this );
  }
};

var groupOptionKeys = [
  'rotate',
  'translate',
  'addTo',
];

function setGroupOptions( shape, options ) {
  for ( var key in options ) {
    if ( groupOptionKeys.includes( key ) ) {
      shape[ key ] = options[ key ];
    }
  }
}

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

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

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

Group.prototype.reset = function() {};

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

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

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

Group.prototype.render = function( ctx ) {
  this.children.forEach( function( child ) {
    child.render( ctx );
  });
};

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

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

function Ellipse( options ) {
  options = this.setPath( options );
  // always keep open
  // fixes overlap bug when lineWidth is greater than radius
  options.closed = false;
  this.create( options );
}

Ellipse.prototype = Object.create( Shape.prototype );
Ellipse.prototype.constructor = Ellipse;

Ellipse.prototype.setPath = function( options ) {
  var w = ( options.width || 1 ) / 2;
  var h = ( options.height || 1 ) / 2;
  options.path = [
    { x: 0, y: -h },
    { arc: [ // top right
      { x: w, y: -h },
      { x: w, y: 0 },
    ]},
    { arc: [ // bottom right
      { x: w, y: h },
      { x: 0, y: h },
    ]},
    { arc: [ // bottom left
      { x: -w, y: h },
      { x: -w, y: 0 },
    ]},
    { arc: [ // bottom left
      { x: -w, y: -h },
      { x: 0, y: -h },
    ]},
  ];
  return options;
};

// -------------------------- Rect -------------------------- //

function Rect( options ) {
  options = this.setPath( options );
  this.create( options );
}

Rect.prototype = Object.create( Shape.prototype );
Rect.prototype.constructor = Rect;

Rect.prototype.setPath = function( options ) {
  var w = ( options.width || 1 ) / 2;
  var h = ( options.height || 1 ) / 2;
  options.path = [
    { x: -w, y: -h },
    { x:  w, y: -h },
    { x:  w, y:  h },
    { x: -w, y:  h },
  ];
  return options;
};

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

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

Group.prototype.create = function( options ) {
  // set options
  setGroupOptions( this, options );

var groupOptionKeys = [
  'rotate',
  'translate',
  'addTo',
];

function setGroupOptions( shape, options ) {
  for ( var key in options ) {
    if ( groupOptionKeys.includes( key ) ) {
      shape[ key ] = options[ key ];
    }
  }
}

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

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

Group.prototype.reset = function() {};

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

Group.prototype.render = function( ctx ) {
  this.children.forEach( function( child ) {
    child.render( ctx );
  });
};

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

// -------------------------- 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 );
};

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

var canvas = document.querySelector('canvas');
var ctx = canvas.getContext('2d');
var w = 360;
var h = 360;
var minWindowSize = Math.min( window.innerWidth, window.innerHeight );
var zoom = Math.min( 3, Math.floor( minWindowSize / (w/2) ) / 2 );
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';
}

// colors
var midnight = '#313';
var eggplant = '#525';
var magenta = '#936';
var amber = '#D65';
var gold = '#FA6';
var white = '#FFF';

var camera = new Shape({
  rendering: false,
});

var layerSpace = 56;

// -- illustration shapes --- //

// background
var background = new Shape({
  translate: { z: layerSpace*2 },
  rendering: false,
  addTo: camera,
});

var bgStripe = new Rect({
  width: 180,
  height: 44,
  addTo: background,
  translate: { y: -40, z: 24 },
  color: magenta,
  lineWidth: 12,
  fill: true,
});
// magenta circle
var bgCircle = new Ellipse({
  width: 96,
  height: 96,
  addTo: background,
  translate: { y: -16, z: 24 },
  color: magenta,
  lineWidth: 24,
  fill: true,
});

// amber stripe
bgStripe.copy({
  translate: { y: -8 },
  color: amber,
});
// amber circle
bgCircle.copy({
  width: 64,
  height: 64,
  translate: { y: -16, },
  color: amber,
});

// gold bg stripe
bgStripe.copy({
  height: 60,
  addTo: background,
  translate: { y: 32, z: -24 },
  color: gold,
});
// gold circle
bgCircle.copy({
  width: 32,
  height: 32,
  translate: { y: -16, z: -24 },
  color: gold,
});

// sun
new Shape({
  addTo: background,
  translate: { y: -16, z: -48 },
  lineWidth: 24,
  color: white,
});

// ----- midBackground ----- //

var midBackground = new Group({
  addTo: camera,
  translate: { z: layerSpace*1 },
});

// ----- midground ----- //

var midground = new Shape({
  rendering: false,
  addTo: camera,
});

var midgroundGroundA = new Shape({
  path: [
    { x: -96, y: 10 },
    { x: -86, y: 10 },
    { arc: [
      { x: -60, y: 42 },
      { x: -26, y: 42 },
    ]},
    { x: -26, y: 74 },
    { x: -96, y: 74 },
  ],
  addTo: midground,
  color: magenta,
  lineWidth: 48,
  fill: true,
});
midgroundGroundA.copy({
  path: [
    { x: -26, y: 42 },
    { arc: [
      { x: -8, y: 74 },
      { x: 36, y: 74 },
    ]},
    { x: 96, y: 74 },
    { x: -26, y: 74 },
  ],
});

function tree( groupOptions, options ) {
  options = extend( options, groupOptions );
  var treeW = options.width/2;
  var treeH = options.height/2;

var pointA = { x: 0, y: -treeH };
  var pointB = { x: treeW, y: treeH };
  var pointC = { x: -treeW, y: treeH };

var treeOptions = extend({
    path: [
      pointA,
      { bezier: [
        pointA,
        { x: treeW, y: treeH*1/3 },
        pointB,
      ]},
      pointC,
      { bezier: [
        { x: -treeW, y: treeH*1/3 },
        pointA,
        pointA,
      ]},
    ],
    fill: true,
  }, options );

var treePlane = new Shape( treeOptions );
  treePlane.copy({
    rotate: { y: TAU/4 },
  });

}

var midgroundTree = {
  addTo: midground,
  color: magenta,
  lineWidth: 2,
};

tree( midgroundTree, {
  width: 10,
  height: 24,
  translate: { x: -86, y: -14, z: 8 },
});

tree( midgroundTree, {
  width: 16,
  height: 36,
  translate: { x: -70, y: -12, z: -14 },
});

tree( midgroundTree, {
  width: 10,
  height: 24,
  translate: { x: -60, y: -4 },
});

tree( midgroundTree, {
  width: 10,
  height: 24,
  translate: { x: -26, y: 12, z: 8 },
});

tree( midgroundTree, {
  width: 10,
  height: 24,
  translate: { x: -18, y: 18, z: -2 },
});

var lonelyTranslate = { x: 32, y: 24 };

tree( midgroundTree, {
  width: 16,
  height: 36,
  translate: lonelyTranslate,
});
// lonely tree stump
new Shape({
  path: [
    { y: 18 },
    { y: 28 },
  ],
  addTo: midground,
  translate: lonelyTranslate,
  color: magenta,
  lineWidth: 4,
});

tree( midgroundTree, {
  width: 10,
  height: 24,
  translate: { x: 64, y: 40, z: -6 },
});
tree( midgroundTree, {
  width: 10,
  height: 24,
  translate: { x: 72, y: 44, z: 2 },
});

// ----- midForeground ----- //

var midForeground = new Shape({
  rendering: false,
  addTo: camera,
  translate: { z: -layerSpace },
});

// midForeground ground part A
var midForegroundGround = new Shape({
  path: [
    { x: 96, y: 26 },
    { x: 72, y: 26 },
    { arc: [
      { x: 56, y: 50 },
      { x: 18, y: 50 },
    ]},
    { x: 18, y: 90 },
    { x: 96, y: 90 },
  ],
  addTo: midForeground,
  color: eggplant,
  lineWidth: 48,
  fill: true,
});
midForegroundGround.copy({
  path: [
    { x: 18, y: 50 },
    { arc: [
      { x: -16, y: 90 },
      { x: -48, y: 72 },
    ]},
    { x: -64, y: 56 },
    { x: -96, y: 48 },
    { x: -96, y: 90 },
    { x: 18, y: 90 },
  ],
});

var midForeTree = {
  addTo: midForeground,
  color: eggplant,
  lineWidth: 2,
};

tree( midForeTree, {
  width: 10,
  height: 24,
  translate: { x: -12, y: 42 },
});
tree( midForeTree, {
  width: 10,
  height: 24,
  translate: { x: 10, y: 22, z: -2 },
});
tree( midForeTree, {
  width: 16,
  height: 36,
  translate: { x: 22, y: 18, z: 6 },
});

tree( midForeTree, {
  width: 16,
  height: 36,
  translate: { x: 76, y: -6, z: -12 },
});
tree( midForeTree, {
  width: 10,
  height: 24,
  translate: { x: 86, y: -4, z: 10 },
});

// ----- foregroundA ----- //

var foregroundA = new Shape({
  path: [
    { x: -96, y: 52 },
    { x: -84, y: 52 },
    { arc: [
      { x: -72, y: 72 },
      { x: -44, y: 72 },
    ]},
    { arc: [
      { x: -32, y: 90 },
      { x: 0, y: 90 },
    ]},
    { x: -96, y: 90 },
  ],
  addTo: camera,
  translate: { z: -layerSpace*2 },
  color: midnight,
  lineWidth: 48,
  fill: true,
});

var foregroundTree = {
  color: midnight,
  lineWidth: 2,
};

tree( foregroundTree, {
  addTo: foregroundA,
  width: 18,
  height: 44,
  translate: { x: -80, y: 18 },
});

tree( foregroundTree, {
  addTo: foregroundA,
  width: 16,
  height: 36,
  translate: { x: -2, y: 64 },
});

var grassBlade = new Shape({
  path: [
    // semi-circle outside on left
    { x: 0, y: 1 },
    { arc: [
      { x: -1, y: 1 },
      { x: -1, y: 0 },
    ]},
    { arc: [
      { x: -1, y: -1 },
      { x:  0, y: -1 },
    ]},
    // shallow semi-circle back
    { arc: [
      { x: -0.5, y: -0.7 },
      { x: -0.5, y: 0 },
    ]},
    { arc: [
      { x: -0.5, y: 0.7 },
      { x: 0, y: 1 },
    ]},
  ],
  addTo: foregroundA,
  translate: { x: -20, y: 56 },
  scale: { x: 8, y: 8 },
  rotate: { z: 0.6 },
  color: midnight,
  lineWidth: 1,
  fill: true,
  closed: false,
});
grassBlade.copy({
  translate: { x: -33, y: 50 },
  rotate: { z: TAU/2 + 0.2 }
});

grassBlade.copy({
  translate: { x: -62, y: 40 },
  rotate: { z: 0.8 },
  scale: { x: 7, y: 7 },
});

grassBlade.copy({
  translate: { x: -64, y: 35 },
  rotate: { z: 0.4 },
  scale: { x: 7, y: 7 },
});

// ----- foregroundB ----- //

var foregroundB = new Shape({
  path: [
    { x: 96, y: 52 },
    { arc: [
      { x: 80, y: 72 },
      { x: 56, y: 72 },
    ]},
    { arc: [
      { x: 40, y: 90 },
      { x: 8, y: 90 },
    ]},
    { x: 0, y: 90 },
    { x: 96, y: 90 },
  ],
  addTo: camera,
  translate: { z: -layerSpace*2 },
  color: midnight,
  lineWidth: 48,
  fill: true,
});

tree( foregroundTree, {
  addTo: foregroundB,
  width: 16,
  height: 36,
  translate: { x: 10, y: 54 },
});

// big tree
var bigTreeTranslate = { x: 58, y: 2 };
tree( foregroundTree, {
  addTo: foregroundB,
  width: 20,
  height: 64,
  translate: bigTreeTranslate,
});
// big tree trunk
new Shape({
  path: [
    { y: 32 },
    { y: 48 },
  ],
  addTo: foregroundB,
  translate: bigTreeTranslate,
  lineWidth: 6,
  color: midnight,
});

tree( foregroundTree, {
  addTo: foregroundB,
  width: 16,
  height: 36,
  translate: { x: 86, y: 26 },
});

grassBlade.copy({
  addTo: foregroundB,
  scale: { x: 12, y: 12 },
  translate: { x: 46, y: 54 },
  rotate: { z: 0 },
});
grassBlade.copy({
  addTo: foregroundB,
  scale: { x: 10, y: 10 },
  translate: { x: 28, y: 58 },
  rotate: { z: TAU/2 - 0.4 },
});

// ----- particles ----- //

// ----- clouds ----- //

var twoCloud = new Shape({
  path: [
    { x: -20, y: 0 },
    { bezier: [
      { x: -13, y: 0 },
      { x: -12, y: -4 },
      { x: -10, y: -4 },
    ]},
    { bezier: [
      { x: -8, y: -4 },
      { x: -8, y: -2 },
      { x: -4, y: -2 },
    ]},
    { bezier: [
      { x: 0, y: -2 },
      { x: 1, y: -6 },
      { x: 4, y: -6 },
    ]},
    { bezier: [
      { x: 7, y: -6 },
      { x: 6, y: 0 },
      { x: 20, y: 0 },
    ]},
  ],
  addTo: camera,
  translate: { x: -84, y: -38, z: layerSpace*1 },
  rotate: { y: TAU*1/16 },
  scale: { x: 1/Math.cos(TAU*1/16) },
  lineWidth: 4,
  color: white,
  fill: true,
});

twoCloud.copy({
  translate: { x: -38, y: -22, z: layerSpace*0.5 },
  rotate: { y: TAU*1/8 },
  scale: { x: 1/Math.cos(TAU*1/8) * -1 },
});

// triple cloud
new Shape({
  path: [
    { x: -32, y: 0 },
    { x: -28, y: 0 },
    { bezier: [
      { x: -22, y: 0 },
      { x: -20, y: -6 },
      { x: -16, y: -6 },
    ]},
    { bezier: [
      { x: -12, y: -6 },
      { x: -12, y: -2 },
      { x: -8, y: -2 },
    ]},
    { bezier: [
      { x: -4, y: -2 },
      { x: -4, y: -6 },
      { x: 0, y: -6 },
    ]},
    { bezier: [
      { x: 4, y: -6 },
      { x: 4, y: -2 },
      { x: 8, y: -2 },
    ]},
    { bezier: [
      { x: 12, y: -2 },
      { x: 12, y: -6 },
      { x: 16, y: -6 },
    ]},
    { bezier: [
      { x: 20, y: -6 },
      { x: 22, y: 0 },
      { x: 28, y: 0 },
    ]},
    { x: 32, y: 0 },
  ],
  addTo: camera,
  translate: { x: 72, y: -52, z: layerSpace*1 },
  rotate: { y: TAU * -1/16 },
  scale: { x: 1/Math.cos(TAU * -1/16) },
  lineWidth: 4,
  color: white,
  fill: true,
});

// ----- stars ----- //

var starA = new Shape({
  path: [
    { x: 0, y: -4 },
    { arc: [
      { x: 0, y: 0 },
      { x: 4, y: 0 },
    ]},
    { arc: [
      { x: 0, y: 0 },
      { x: 0, y: 4 },
    ]},
    { arc: [
      { x: 0, y: 0 },
      { x: -4, y: 0 },
    ]},
    { arc: [
      { x: 0, y: 0 },
      { x: 0, y: -4 },
    ]},
  ],
  addTo: camera,
  translate: { x: -50, y: -50, z: layerSpace*1.5 },
  color: gold,
  lineWidth: 2,
  fill: true,
});
starA.copy({
  rotate: { y: TAU/4 },
});

var starB = starA.copy({
  translate: { x: 42, y: -20, z: layerSpace*0.5 },
});
starB.copy({
  rotate: { y: TAU/4 },
});

// ----- bird ----- //

new Shape({
  path: [
    { x: -6, y: -4 },
    { x: -4, y: -4 },
    { arc: [
      { x: 0, y: -4 },
      { x: 0, y: 0 },
    ]},
    { arc: [
      { x: 0, y: -4 },
      { x: 4, y: -4 },
    ]},
    { x: 6, y: -4 },
    { move: [{ z: -2, y: 0 }] },
    { z: 3, y: 0 },
  ],
  addTo: camera,
  translate: { x: 18, y: -30, z: layerSpace*1 },
  lineWidth: 3,
  color: midnight,
  closed: false,
});

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

var shapes = camera.getShapes();

// -- animate --- //

var isRotating = true;
var t = 0;
var tSpeed = 1/320;

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

animate();

// -- update -- //

function update() {
  if ( isRotating ) {
    t += tSpeed;
    var theta = easeInOut( t ) * TAU;
    camera.rotate.y = Math.sin( theta ) * TAU/32;
    camera.rotate.x = ( Math.cos( theta ) * -0.5 + 0.5 ) * TAU/32;
  }

camera.update();
  // sort
  shapes.forEach( function( shape ) {
    shape.updateSortValue();
  });
  // perspective sort
  shapes.sort( function( a, b ) {
    return b.sortValue - a.sortValue;
  });
}

function easeInOut( i ) {
  i = i % 1;
  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;
  i2 = i2 / 2;
  return isFirstHalf ? i2 : i2*-1 + 1;
}

// -- 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 );

shapes.forEach( function( shape ) {
    shape.render( ctx );
  });

ctx.restore();
}

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

// click drag to rotate
var dragStartAngleX, dragStartAngleY;

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

document.querySelector('.reset-button').onclick = function() {
  isRotating = false;
  camera.rotate.set({ x: 0, y: 0 });
};

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