Extract BaseLightSource abstract class from light-sources

src/common/model/light-sources/ArcLightSource.ts

@@ -8,21 +8,19 @@
  * π/2 = down (positive y-axis), consistent with Math.atan2(dy, dx).
  */
 
-import { BaseElement } from "../optics/BaseElement.js";
 import type { Point } from "../optics/Geometry.js";
 import { normalize, point } from "../optics/Geometry.js";
 import {
   BRIGHTNESS_CONTINUOUS_THRESHOLD,
-  BRIGHTNESS_NORMALIZE,
   POLARIZATION_SPLIT,
   RAY_DENSITY_SCALE,
 } from "../optics/OpticsConstants.js";
-import type { ElementCategory, SimulationRay, ViewMode } from "../optics/OpticsTypes.js";
+import type { SimulationRay, ViewMode } from "../optics/OpticsTypes.js";
+import { BaseLightSource } from "./BaseLightSource.js";
 import { GREEN_WAVELENGTH } from "./LightSourceConstants.js";
 
-export class ArcLightSource extends BaseElement {
+export class ArcLightSource extends BaseLightSource {
   public readonly type = "ArcSource";
-  public readonly category: ElementCategory = "lightSource";
 
   public position: Point;
 
@@ -38,22 +36,17 @@ export class ArcLightSource extends BaseElement {
    */
   public emissionAngle: number;
 
-  public brightness: number;
-  public wavelength: number;
-
   public constructor(
     position: Point,
     direction = 0,
     emissionAngle = Math.PI / 6, // 30 degrees
     brightness = 0.5,
     wavelength = GREEN_WAVELENGTH,
   ) {
-    super();
+    super(brightness, wavelength);
     this.position = position;
     this.direction = direction;
     this.emissionAngle = emissionAngle;
-    this.brightness = brightness;
-    this.wavelength = wavelength;
   }
 
   public override emitRays(rayDensity: number, _mode: ViewMode): SimulationRay[] {
@@ -69,8 +62,7 @@ export class ArcLightSource extends BaseElement {
       ? maxRays
       : Math.max(1, Math.round((this.brightness / BRIGHTNESS_CONTINUOUS_THRESHOLD) * maxRays));
     const angularStep = beta / numRays;
-    const bBase = isContinuous ? this.brightness : BRIGHTNESS_CONTINUOUS_THRESHOLD;
-    const b = bBase / BRIGHTNESS_NORMALIZE;
+    const b = this.normalizeBrightness();
 
     const halfAngle = beta / 2;
     const startAngle = this.direction - halfAngle;

src/common/model/light-sources/BaseLightSource.ts

@@ -0,0 +1,45 @@
+/**
+ * BaseLightSource.ts
+ *
+ * Abstract base class for all single-wavelength light source elements.
+ * Centralises the three properties shared by every concrete light source
+ * (brightness, wavelength, category) and provides a protected
+ * brightness-normalization helper used during ray emission.
+ */
+
+import { BaseElement } from "../optics/BaseElement.js";
+import {
+  BRIGHTNESS_CONTINUOUS_THRESHOLD,
+  BRIGHTNESS_NORMALIZE,
+} from "../optics/OpticsConstants.js";
+import type { ElementCategory } from "../optics/OpticsTypes.js";
+import { GREEN_WAVELENGTH } from "./LightSourceConstants.js";
+
+export abstract class BaseLightSource extends BaseElement {
+  public readonly category: ElementCategory = "lightSource";
+
+  public brightness: number;
+  public wavelength: number;
+
+  protected constructor(brightness: number, wavelength: number = GREEN_WAVELENGTH) {
+    super();
+    this.brightness = brightness;
+    this.wavelength = wavelength;
+  }
+
+  /**
+   * Returns the per-ray brightness factor (before polarization split).
+   *
+   * Two emission modes:
+   * - Discrete  (brightness < BRIGHTNESS_CONTINUOUS_THRESHOLD): every ray
+   *   carries a fixed intensity of BRIGHTNESS_CONTINUOUS_THRESHOLD so that
+   *   visual appearance is consistent regardless of how many rays are drawn.
+   * - Continuous (brightness >= BRIGHTNESS_CONTINUOUS_THRESHOLD): intensity
+   *   scales linearly with brightness up to BRIGHTNESS_NORMALIZE.
+   */
+  protected normalizeBrightness(): number {
+    const isContinuous = this.brightness >= BRIGHTNESS_CONTINUOUS_THRESHOLD;
+    const bBase = isContinuous ? this.brightness : BRIGHTNESS_CONTINUOUS_THRESHOLD;
+    return bBase / BRIGHTNESS_NORMALIZE;
+  }
+}

src/common/model/light-sources/BeamSource.ts

@@ -6,38 +6,32 @@
  * evenly distributed along the segment.
  */
 
-import { BaseElement } from "../optics/BaseElement.js";
 import type { Point } from "../optics/Geometry.js";
 import { distance, normalize, point, subtract } from "../optics/Geometry.js";
 import {
   BEAM_RAY_DENSITY_SCALE,
   BRIGHTNESS_CONTINUOUS_THRESHOLD,
-  BRIGHTNESS_NORMALIZE,
   POLARIZATION_SPLIT,
   RAY_DENSITY_SCALE,
 } from "../optics/OpticsConstants.js";
-import type { ElementCategory, SimulationRay, ViewMode } from "../optics/OpticsTypes.js";
+import type { SimulationRay, ViewMode } from "../optics/OpticsTypes.js";
+import { BaseLightSource } from "./BaseLightSource.js";
 import { GREEN_WAVELENGTH } from "./LightSourceConstants.js";
 
-export class BeamSource extends BaseElement {
+export class BeamSource extends BaseLightSource {
   public readonly type = "Beam";
-  public readonly category: ElementCategory = "lightSource";
 
   /** First endpoint of the segment perpendicular to beam direction. */
   public p1: Point;
   /** Second endpoint of the segment perpendicular to beam direction. */
   public p2: Point;
-  public brightness: number;
-  public wavelength: number;
   /** Divergence half-angle in degrees (0 = perfectly parallel). */
   public emisAngle: number;
 
   public constructor(p1: Point, p2: Point, brightness = 0.5, wavelength = GREEN_WAVELENGTH, emisAngle = 0) {
-    super();
+    super(brightness, wavelength);
     this.p1 = p1;
     this.p2 = p2;
-    this.brightness = brightness;
-    this.wavelength = wavelength;
     this.emisAngle = emisAngle;
   }
 
@@ -57,8 +51,7 @@ export class BeamSource extends BaseElement {
     const angularStep = (Math.PI * 2) / Math.max(1, Math.floor(rayDensity * RAY_DENSITY_SCALE));
     const numAngledRays = 1 + Math.max(0, Math.ceil(halfAngle / angularStep) - 1) * 2;
     const brightnessFactor = 1.0 / numAngledRays;
-    const bBase = isContinuous ? this.brightness : BRIGHTNESS_CONTINUOUS_THRESHOLD;
-    const b = Math.min((bBase / BRIGHTNESS_NORMALIZE) * brightnessFactor, 1);
+    const b = Math.min(this.normalizeBrightness() * brightnessFactor, 1);
 
     const rays: SimulationRay[] = [];
 

src/common/model/light-sources/PointSourceElement.ts

@@ -5,31 +5,25 @@
  * directions. The angular spacing of rays depends on rayDensity.
  */
 
-import { BaseElement } from "../optics/BaseElement.js";
 import type { Point } from "../optics/Geometry.js";
 import { point } from "../optics/Geometry.js";
 import {
   BRIGHTNESS_CONTINUOUS_THRESHOLD,
-  BRIGHTNESS_NORMALIZE,
   POLARIZATION_SPLIT,
   RAY_DENSITY_SCALE,
 } from "../optics/OpticsConstants.js";
-import type { ElementCategory, SimulationRay, ViewMode } from "../optics/OpticsTypes.js";
+import type { SimulationRay, ViewMode } from "../optics/OpticsTypes.js";
+import { BaseLightSource } from "./BaseLightSource.js";
 import { GREEN_WAVELENGTH } from "./LightSourceConstants.js";
 
-export class PointSourceElement extends BaseElement {
+export class PointSourceElement extends BaseLightSource {
   public readonly type = "PointSource";
-  public readonly category: ElementCategory = "lightSource";
 
   public position: Point;
-  public brightness: number;
-  public wavelength: number;
 
   public constructor(position: Point, brightness = 0.5, wavelength = GREEN_WAVELENGTH) {
-    super();
+    super(brightness, wavelength);
     this.position = position;
-    this.brightness = brightness;
-    this.wavelength = wavelength;
   }
 
   public override emitRays(rayDensity: number, mode: ViewMode): SimulationRay[] {
@@ -42,8 +36,7 @@ export class PointSourceElement extends BaseElement {
     const startAngle = mode === "observer" ? -angularStep * 2 + 1e-6 : 0;
     // In discrete mode every ray has fixed intensity (BRIGHTNESS_CONTINUOUS_THRESHOLD).
     // In continuous mode intensity scales with brightness up to BRIGHTNESS_NORMALIZE.
-    const bBase = isContinuous ? this.brightness : BRIGHTNESS_CONTINUOUS_THRESHOLD;
-    const b = bBase / BRIGHTNESS_NORMALIZE;
+    const b = this.normalizeBrightness();
 
     const rays: SimulationRay[] = [];
     let first = true;

src/common/model/light-sources/SingleRaySource.ts

@@ -5,28 +5,23 @@
  * a second point that indicates direction. Emits exactly one ray.
  */
 
-import { BaseElement } from "../optics/BaseElement.js";
 import type { Point } from "../optics/Geometry.js";
 import { normalize, point, subtract } from "../optics/Geometry.js";
 import { POLARIZATION_SPLIT } from "../optics/OpticsConstants.js";
-import type { ElementCategory, SimulationRay, ViewMode } from "../optics/OpticsTypes.js";
+import type { SimulationRay, ViewMode } from "../optics/OpticsTypes.js";
+import { BaseLightSource } from "./BaseLightSource.js";
 import { GREEN_WAVELENGTH } from "./LightSourceConstants.js";
 
-export class SingleRaySource extends BaseElement {
+export class SingleRaySource extends BaseLightSource {
   public readonly type = "SingleRay";
-  public readonly category: ElementCategory = "lightSource";
 
   public p1: Point;
   public p2: Point;
-  public brightness: number;
-  public wavelength: number;
 
   public constructor(p1: Point, p2: Point, brightness = 1, wavelength = GREEN_WAVELENGTH) {
-    super();
+    super(brightness, wavelength);
     this.p1 = p1;
     this.p2 = p2;
-    this.brightness = brightness;
-    this.wavelength = wavelength;
   }
 
   public override emitRays(_rayDensity: number, _mode: ViewMode): SimulationRay[] {