☀️ Adds sun elevation calculator

app/src/lib/sceneBuilder.ts

@@ -25,6 +25,7 @@ import { OrbitControls } from 'three/examples/jsm/controls/OrbitControls';
 import { TransformControls } from 'three/examples/jsm/controls/TransformControls';
 import { type URDFJoint, type URDFMimicJoint, type URDFRobot } from 'urdf-loader';
 import { PointerURDFDragControls } from 'urdf-loader/src/URDFDragControls';
+import { sunCalculator } from './utilities/position-utilities';
 
 export const addScene = () => new Scene();
 
@@ -55,13 +56,6 @@ type directionalLight = position & light;
 
 type gridHelperOptions = gridOptions & position;
 
-function calculateCurrentSunElevation() {
-	let now = new Date();
-	let decimalTime = now.getHours() + now.getMinutes() / 60;
-	let normalizedTime = (decimalTime % 12) / 6 - 1;
-	return 10 * Math.sin(normalizedTime * Math.PI);
-}
-
 export default class SceneBuilder {
 	public scene: Scene;
 	public camera!: PerspectiveCamera;
@@ -107,7 +101,7 @@ export default class SceneBuilder {
 			rayleigh: 3,
 			mieCoefficient: 0.005,
 			mieDirectionalG: 0.7,
-			elevation: calculateCurrentSunElevation(),
+			elevation: sunCalculator.calculateSunElevation(),
 			azimuth: 180,
 			exposure: this.renderer.toneMappingExposure
 		};

app/src/lib/utilities/position-utilities.ts

@@ -0,0 +1,84 @@
+class SunCalculator {
+	calculateSunElevation(lat: number = 55, lon: number = 12) {
+		const now = new Date();
+		const JD = this.getJulianDate(now);
+		const solarDec = this.getSolarDeclination(JD);
+		const solarTime = this.getSolarTime(now, lon);
+
+		const hourAngle = (solarTime - 12) * 15;
+		const elevation = Math.asin(
+			Math.sin(this.degToRad(lat)) * Math.sin(solarDec) +
+				Math.cos(this.degToRad(lat)) * Math.cos(solarDec) * Math.cos(this.degToRad(hourAngle))
+		);
+
+		return this.radToDeg(elevation);
+	}
+
+	getJulianDate(date: Date) {
+		const Y = date.getUTCFullYear();
+		const M = date.getUTCMonth() + 1;
+		const D =
+			date.getUTCDate() +
+			date.getUTCHours() / 24 +
+			date.getUTCMinutes() / 1440 +
+			date.getUTCSeconds() / 86400;
+		const A = Math.floor((14 - M) / 12);
+		const Y1 = Y + 4800 - A;
+		const M1 = M + 12 * A - 3;
+		return (
+			D +
+			Math.floor((153 * M1 + 2) / 5) +
+			365 * Y1 +
+			Math.floor(Y1 / 4) -
+			Math.floor(Y1 / 100) +
+			Math.floor(Y1 / 400) -
+			32045
+		);
+	}
+
+	getSolarDeclination(JulianDate: number) {
+		const n = JulianDate - 2451545;
+		const L = (280.46 + 0.9856474 * n) % 360;
+		const g = this.degToRad((357.528 + 0.9856003 * n) % 360);
+		const lambda = this.degToRad(L + 1.915 * Math.sin(g) + 0.02 * Math.sin(2 * g));
+		return Math.asin(Math.sin(lambda) * Math.sin(this.degToRad(23.44)));
+	}
+
+	getSolarTime(date: Date, lon: number) {
+		const EoT = this.getEquationOfTime(date);
+		const offset = date.getTimezoneOffset() / 60;
+		const standardMeridian = Math.round(lon / 15) * 15;
+		const solarTime =
+			date.getUTCHours() +
+			(date.getUTCMinutes() + (4 * (standardMeridian - lon) + EoT)) / 60 -
+			offset;
+		return (solarTime + 24) % 24;
+	}
+
+	getEquationOfTime(date: Date) {
+		const JD = this.getJulianDate(date);
+		const n = JD - 2451545;
+		const g = this.degToRad((357.528 + 0.9856003 * n) % 360);
+		const q = this.degToRad((280.46 + 0.9856474 * n) % 360);
+		return (
+			4 *
+			this.radToDeg(
+				0.000075 +
+					0.001868 * Math.cos(q) -
+					0.032077 * Math.sin(g) -
+					0.014615 * Math.cos(2 * q) -
+					0.040849 * Math.sin(2 * g)
+			)
+		);
+	}
+
+	degToRad(deg: number) {
+		return deg * (Math.PI / 180);
+	}
+
+	radToDeg(rad: number) {
+		return rad * (180 / Math.PI);
+	}
+}
+
+export const sunCalculator = new SunCalculator();