Minor improvements to the aperture of PhotonDetector, see #65

js/photons/model/PhotonDetector.ts

@@ -48,6 +48,9 @@ export default class PhotonDetector implements TPhotonInteraction {
   // detection aperture width, in meters
   public readonly apertureDiameter = PHOTON_BEAM_WIDTH * 1.75;
 
+  // detection aperture height, in meters
+  public readonly apertureHeight = 0.05;
+
   // A line in model space that represents the position of the detection aperture.  If a photon crosses this line, it
   // will be detected but not absorbed.
   public readonly detectionLine: Line;
@@ -74,14 +77,13 @@ export default class PhotonDetector implements TPhotonInteraction {
     this.position = position;
     this.detectionDirection = detectionDirection;
     this.displayMode = options.displayMode!;
-    const apertureHeight = 0.02;
     this.detectionLine = new Line(
       position.plus( new Vector2( -this.apertureDiameter / 2, 0 ) ),
       position.plus( new Vector2( this.apertureDiameter / 2, 0 ) )
     );
     this.absorptionLine = new Line(
-      position.plus( new Vector2( -this.apertureDiameter / 2, this.detectionDirection === 'up' ? apertureHeight : -apertureHeight ) ),
-      position.plus( new Vector2( this.apertureDiameter / 2, this.detectionDirection === 'up' ? apertureHeight : -apertureHeight ) )
+      position.plus( new Vector2( -this.apertureDiameter / 2, this.detectionDirection === 'up' ? this.apertureHeight : -this.apertureHeight ) ),
+      position.plus( new Vector2( this.apertureDiameter / 2, this.detectionDirection === 'up' ? this.apertureHeight : -this.apertureHeight ) )
     );
 
     this.detectionRateProperty = new AveragingCounterNumberProperty( {

js/photons/view/PhotonDetectorNode.ts

@@ -43,15 +43,19 @@ export default class PhotonDetectorNode extends Node {
 
     // Create the detection aperture.  This is essentially the anchor point for reset of the layout, meaning that the
     // other nodes are positioned relative to this.
-    const apertureHeightInView = modelViewTransform.modelToViewDeltaY(
-      -Math.abs( model.detectionLine.start.y - model.absorptionLine.end.y )
-    );
-    const apertureDiameterInView = -modelViewTransform.modelToViewDeltaY( model.apertureDiameter );
+    const apertureHeightInView = -modelViewTransform.modelToViewDeltaY( model.apertureHeight );
+    const apertureDiameterInView = modelViewTransform.modelToViewDeltaX( model.apertureDiameter );
+    const apertureCenterY = model.detectionDirection === 'up' ?
+                            model.position.y + model.apertureHeight / 2 :
+                            model.position.y - model.apertureHeight / 2;
     const aperture = new Rectangle( 0, 0, apertureDiameterInView, apertureHeightInView, {
       fill: new LinearGradient( 0, 0, apertureDiameterInView, 0 )
         .addColorStop( 0, new Color( '#FFDDEE' ) )
         .addColorStop( 1, Color.DARK_GRAY ),
-      center: modelViewTransform.modelToViewPosition( model.position ),
+      stroke: Color.DARK_GRAY,
+      lineWidth: 1,
+      centerX: modelViewTransform.modelToViewX( model.position.x ),
+      centerY: modelViewTransform.modelToViewY( apertureCenterY ),
       opacity: 0.3
     } );
 
@@ -143,8 +147,6 @@ export default class PhotonDetectorNode extends Node {
     );
 
     super( options );
-
-    this.centerY += model.detectionDirection === 'up' ? -apertureHeightInView / 2 : apertureHeightInView / 2;
   }
 }