New Shape; Horn

.gitignore

@@ -1,3 +1,4 @@
 .DS_Store
 node_modules/
 bower_components/
+*.bak

js/horn.js

@@ -0,0 +1,263 @@
+/**
+ * Horn composite shape
+ */
+
+( function( root, factory ) {
+  // module definition
+  if ( typeof module == 'object' && module.exports ) {
+    // CommonJS
+    module.exports = factory( require('./boilerplate'),
+        require('./path-command'), require('./shape'), require('./group'),
+        require('./vector') );
+  } else {
+    // browser global
+    var Zdog = root.Zdog;
+    Zdog.Horn = factory( Zdog, Zdog.PathCommand, Zdog.Shape,
+        Zdog.Group, Zdog.Vector );
+  }
+}( this, function factory( utils, PathCommand, Shape, Group, Vector ) {
+
+function noop() {}
+
+// ----- HornGroup ----- //
+
+var HornGroup = Group.subclass({
+  color: '#333',
+  updateSort: true,
+});
+
+HornGroup.prototype.create = function() {
+  Group.prototype.create.apply( this, arguments );
+
+  // vectors used for calculation
+  this.renderApex = new Vector();
+  this.tangentFrontA = new Vector();
+  this.tangentFrontB = new Vector();
+  this.tangentRearA = new Vector();
+  this.tangentRearB = new Vector();
+
+  this.pathCommands = [
+    new PathCommand( 'move', [ {} ] ),
+    new PathCommand( 'line', [ {} ] ),
+	new PathCommand( 'line', [ {} ] ),
+	new PathCommand( 'line', [ {} ] ),
+  ];
+};
+
+HornGroup.prototype.render = function( ctx, renderer ) {
+  this.renderHornSurface( ctx, renderer );
+  Group.prototype.render.apply( this, arguments );
+};
+
+HornGroup.prototype.renderHornSurface = function( ctx, renderer ) {
+  if ( !this.visible ) {
+    return;
+  }
+  // render horn surface
+  var elem = this.getRenderElement( ctx, renderer );
+  var frontBase = this.frontBase;
+  var frontDiameter = frontBase.stroke;
+  var rearBase = this.rearBase;
+  var rearDiameter = rearBase.stroke;
+  var scale = frontBase.renderNormal.magnitude();
+  var frontRadius = frontDiameter/2 * scale;
+  var rearRadius = rearDiameter/2 * scale;
+
+  this.renderApex.set( rearBase.renderOrigin )
+    .subtract( frontBase.renderOrigin );
+
+  // calculate tangents.
+  var scale = frontBase.renderNormal.magnitude();
+  var apexDistance = this.renderApex.magnitude2d();
+  var normalDistance = frontBase.renderNormal.magnitude2d();
+  // eccentricity
+  var eccenAngle = Math.acos( normalDistance / scale );
+  var biggerRadius =  (frontRadius > rearRadius) ? frontRadius : rearRadius;
+  var eccenPercent;
+  if (frontRadius == 0 || rearRadius == 0) {
+	  eccenPercent = 1.0;
+  } else {
+	  eccenPercent = (Math.abs(frontRadius - rearRadius) / biggerRadius);
+  }
+  var eccen = Math.sin( eccenAngle ) * Math.sqrt(eccenPercent);
+  // does apex extend beyond eclipse of face
+  apexDistance = apexDistance + frontRadius/4 + rearRadius/4;
+  var isApexVisible = frontRadius * eccen < apexDistance &&
+                      rearRadius * eccen < apexDistance;
+  if ( !isApexVisible ) {
+    return;
+  }
+  // update tangents
+  // TODO: try something more like horn_old.js updateSortValue()
+  var apexAngle = Math.atan2( frontBase.renderNormal.y, frontBase.renderNormal.x ) +
+      TAU/2;
+  var projectFrontLength = (apexDistance + frontRadius) / eccen;
+  var projectRearLength = (apexDistance + rearRadius) / eccen;
+  var projectFrontAngle = Math.acos( frontRadius / projectFrontLength );
+  var projectRearAngle = Math.acos( rearRadius / -projectRearLength );
+  // set tangent points
+  var tangentFrontA = this.tangentFrontA;
+  var tangentFrontB = this.tangentFrontB;
+  var tangentRearA = this.tangentRearA;
+  var tangentRearB = this.tangentRearB;
+
+  tangentFrontA.x = Math.cos( projectFrontAngle ) * frontRadius * eccen;
+  tangentFrontA.y = Math.sin( projectFrontAngle ) * frontRadius;
+  tangentRearA.x = Math.cos( projectRearAngle ) * rearRadius * eccen;
+  tangentRearA.y = Math.sin( projectRearAngle ) * rearRadius;
+
+  tangentFrontB.set( this.tangentFrontA );
+  tangentFrontB.y *= -1;
+  tangentRearB.set( this.tangentRearA );
+  tangentRearB.y *= -1;
+
+  tangentFrontA.rotateZ( apexAngle);
+  tangentFrontB.rotateZ( apexAngle);
+  tangentFrontA.add( frontBase.renderOrigin );
+  tangentFrontB.add( frontBase.renderOrigin );
+  tangentRearA.rotateZ( apexAngle + TAU/2);
+  tangentRearB.rotateZ( apexAngle + TAU/2);
+  tangentRearA.add( rearBase.renderOrigin );
+  tangentRearB.add( rearBase.renderOrigin );
+
+
+  // set path command render points
+  this.pathCommands[0].renderPoints[0].set( tangentFrontA );
+  this.pathCommands[1].renderPoints[0].set( tangentRearB );
+  this.pathCommands[2].renderPoints[0].set( tangentRearA );
+  this.pathCommands[3].renderPoints[0].set( tangentFrontB );
+
+  if ( renderer.isCanvas ) {
+    ctx.lineCap = 'butt'; // nice
+  }
+  renderer.renderPath( ctx, elem, this.pathCommands );
+  //renderer.stroke( ctx, elem, true, '#333', 0.1 ); // remove once testing is done.
+  renderer.fill( ctx, elem, true, this.color );
+  renderer.end( ctx, elem );
+
+  if ( renderer.isCanvas ) {
+    ctx.lineCap = 'round'; // reset
+  }
+};
+
+var svgURI = 'http://www.w3.org/2000/svg';
+
+HornGroup.prototype.getRenderElement = function( ctx, renderer ) {
+  if ( !renderer.isSvg ) {
+    return;
+  }
+  if ( !this.svgElement ) {
+    // create svgElement
+    this.svgElement = document.createElementNS( svgURI, 'path');
+  }
+  return this.svgElement;
+};
+
+// prevent double-creation in parent.copyGraph()
+// only create in Horn.create()
+HornGroup.prototype.copyGraph = noop;
+
+// ----- HornCap ----- //
+
+var HornCap = Shape.subclass();
+
+HornCap.prototype.copyGraph = noop;
+
+// ----- Horn ----- //
+
+var Horn = Shape.subclass({
+  frontDiameter: 1,
+  rearDiameter: 1,
+  length: 1,
+  frontFace: undefined,
+  fill: true,
+});
+
+var TAU = utils.TAU;
+
+Horn.prototype.create = function(/* options */) {
+  // call super
+  Shape.prototype.create.apply( this, arguments );
+  // composite shape, create child shapes
+  // HornGroup to render horn surface then bases
+  this.group = new HornGroup({
+    addTo: this,
+    color: this.color,
+    visible: this.visible,
+  });
+  var baseZ = this.length/2;
+  var baseColor = this.backface || true;
+  // front outside base
+  this.frontBase = this.group.frontBase = new HornCap({
+    addTo: this.group,
+    translate: { z: (baseZ - this.frontDiameter/2) },
+    rotate: { y: TAU/2 },
+    color: this.color,
+    stroke: this.frontDiameter,
+    fill: this.fill,
+    backface: this.frontFace || baseColor,
+    visible: this.visible,
+  });
+  // back outside base
+  this.rearBase = this.group.rearBase = new HornCap({
+    addTo: this.group,
+    translate: { z: (-baseZ + this.rearDiameter/2) },
+    rotate: { y: 0 },
+    color: this.color,
+    stroke: this.rearDiameter,
+    fill: this.fill,
+    backface: baseColor,
+    visible: this.visible,
+  });
+
+};
+
+Horn.prototype.updateFrontCapDiameter = function(size) {
+	this.frontBase.stroke = size;
+	var baseZ = this.length/2;
+	this.frontBase.translate.z = (baseZ - size/2);
+}
+
+Horn.prototype.updateRearCapDiameter = function(size) {
+	this.rearBase.stroke = size;
+	var baseZ = this.length/2;
+	this.rearBase.translate.z = (-baseZ + size/2);
+}
+
+// Horn shape does not render anything
+Horn.prototype.render = function() {};
+
+// ----- set child properties ----- //
+
+var childProperties = [ 'stroke', 'fill', 'color', 'visible',
+                        'frontDiameter', 'rearDiameter' ];
+childProperties.forEach( function( property ) {
+  // use proxy property for custom getter & setter
+  var _prop = '_' + property;
+  Object.defineProperty( Horn.prototype, property, {
+    get: function() {
+      return this[ _prop ];
+    },
+    set: function( value ) {
+      this[ _prop ] = value;
+      // set property on children
+      if ( this.frontBase ) {
+		if (property === 'frontDiameter') {
+		  this.updateFrontCapDiameter(value);
+		}
+		if (property === 'rearDiameter') {
+		  this.updateRearCapDiameter(value);
+		}
+        this.frontBase[ property ] = value;
+        this.rearBase[ property ] = value;
+        this.group[ property ] = value;
+      }
+    },
+  });
+});
+
+// TODO child property setter for backface, frontBaseColor, & rearBaseColor
+
+return Horn;
+
+}));

js/index.js

@@ -24,6 +24,7 @@
         require('./hemisphere'),
         require('./cylinder'),
         require('./cone'),
+		require('./horn'),
         require('./box')
     );
   } else if ( typeof define == 'function' && define.amd ) {
@@ -32,7 +33,7 @@
   }
 })( this, function factory( Zdog, CanvasRenderer, SvgRenderer, Vector, Anchor,
     Dragger, Illustration, PathCommand, Shape, Group, Rect, RoundedRect,
-    Ellipse, Polygon, Hemisphere, Cylinder, Cone, Box ) {
+    Ellipse, Polygon, Hemisphere, Cylinder, Cone, Horn, Box ) {
 
       Zdog.CanvasRenderer = CanvasRenderer;
       Zdog.SvgRenderer = SvgRenderer;
@@ -50,6 +51,7 @@
       Zdog.Hemisphere = Hemisphere;
       Zdog.Cylinder = Cylinder;
       Zdog.Cone = Cone;
+	  Zdog.Horn = Horn;
       Zdog.Box = Box;
 
       return Zdog;