My application calculates three distinct Meesus Double [x, y, z] Radian values to light a sphere in RealityKit with DirectionalLight. It is my understanding that I must use (simd_quatf) for each radian value to properly light the sphere in the view. The code correctly [orientates] the sphere with the combined (simd_quatf) DirectionalLight in the view, but the illumination (Z-axis) fails to properly illuminate the sphere with the expected result, compared to associated Meesus web page images. For the moment, I do not know how to correct the (Z-axis). Curious for a suggestion ... :] // Location values. let theLatitude: Double = 51.13107260 let theLongitude: Double = -114.01127910 let currentDate: Date = Date() struct TheCalculatedMoonPhaseTest_ContentView: View { var body: some View { VStack { if #available(macOS 15.0, *) { RealityView { content in let moonSphere_Entity = Entity.createSphere(radius: 0.90, color: .black) moonSphere.Entity.name = "MoonSphere" moonSphere.Entity.position = SIMD3<Float>(x: 0, y: 0, z: 0) content.add(moonSphere.Entity) let sunLight_Entity = createDirectionalLight(latitude: theLatitude, longitude: theLongitude, date: currentDate) content.add(sunLight_Entity) } // End of [RealityView] } else { // Earlier version required. } // End of [if #available(macOS 15.0, *)] } // End of [VStack] .background(Color.black) } // End of [var body: some View] // MARK: - 🟠🟠🟠🟠 [SET THE BACKGROUND COLOUR] 🟠🟠🟠🟠 var backgroundColor: Color = Color.init(.black) // MARK: - 🟠🟠🟠🟠 [CREATE THE DIRECTIONAL LIGHT FOR THE SPHERE] 🟠🟠🟠🟠 func createDirectionalLight(latitude: Double, longitude: Double, date: Date) -> Entity { let directionalLight = DirectionalLight() directionalLight.light.color = .white directionalLight.light.intensity = 1000000 directionalLight.shadow = DirectionalLightComponent.Shadow() directionalLight.shadow?.maximumDistance = 5 directionalLight.shadow?.depthBias = 1 // MARK: 🟠🟠🟠🟠 Retrieve the [MEESUS MOON AGE VALUES] from the [CONSTANT FOLDER] 🟠🟠🟠🟠 let theMeesusMoonAge_LunarAgeDaysValue = 25.90567592898601 if theMeesusMoonAge_LunarAgeDaysValue >= 23.10 && theMeesusMoonAge_LunarAgeDaysValue < (29.530588853 - 1.00) { let someCalculatedX_WestEastRadian: Float = Float(1.00) // Identify the sphere’s DirectionalLight Tilt Angle (Y) radian value :: // Note :: The following Tilt Angle is corrected to [Zenith] with the [MeesusCalculatedTilt_Angle] minus the [MeesusCalculatedPar_Angle]. let someCalculatedY_TiltAngleRadian: Float = Float(1.3396086) // Identify the sphere’s DirectionalLight Illumination (Z) radian Value :: // Note :: The Meesus calculated illumination fraction is converted to degrees, then converted to a radian value. let someCalculatedZ_IlluminationAngleRadian: Float = Float(0.45176168630244457) // <=== 14.3800% Illumination. // Define rotation angles in radians for X, Y, and Z axes. let x_Radians = someCalculatedX_WestEastRadian let y_Radians = someCalculatedY_TiltAngleRadian let z_Radians = someCalculatedZ_IlluminationAngleRadian // Identify and separate the quaternion [simd_quatf] for each Radian. let q_X = simd_quatf(angle: x_Radians, axis: SIMD3<Float>(1, 0, 0)) let q_Y = simd_quatf(angle: y_Radians, axis: SIMD3<Float>(0, 1, 0)) let q_Z = simd_quatf(angle: z_Radians, axis: SIMD3<Float>(0, 0, 1)) // Apply and combine the rotations, where order matters. let combinedRotation = q_Z * q_Y * q_X // Identify the [Combined Rotation]. // The [MyMoonMeesus] :: [WANING CRESCENT] calculated [combinedRotation] :: simd_quatf(real: 0.73715997, imag: SIMD3<Float>(0.24427173, 0.61516714, -0.13599981)) ° Radians // Normalize the [combinedRotation]. let theNormalizesRotation = simd_normalize(combinedRotation) // Identify the [Normalized Combined Rotation]. // The [MyMoonMeesus] :: [WANING CRESCENT] calculated [normalizedRotation] :: simd_quatf(real: 0.73715997, imag: SIMD3<Float>(0.24427173, 0.61516714, -0.13599981)) ° Radians // Assume the [theNormalizesRotation] appears reversed. let theCorrectedRotation = theNormalizesRotation.inverse // Identify the [Reversed Combined Rotation]. // The [MyMoonMeesus] :: [WANING CRESCENT] calculated [correctedRotation] :: simd_quatf(real: 0.73715997, imag: SIMD3<Float>(-0.24427173, -0.61516714, 0.13599981)) ° Radians // Apply the [Corrected Rotation] to the entity. directionalLight.transform.rotation *= theCorrectedRotation // Add the [directionalLight] to the scene :: let anchor = AnchorEntity() anchor.addChild(directionalLight) } // End of [if theMeesusMoonAge_LunarAgeDaysValue >= 23.10 && theMeesusMoonAge_LunarAgeDaysValue < (29.530588853 - 1.00)] return directionalLight } // End of [func createDirectionalLight(latitude: Double, longitude: Double, date: Date) -> Entity] } // End of [struct TheCalculatedMoonPhaseTest_ContentView: View] // MARK: 🟠🟠🟠🟠 [ENTITY HELPER EXTENSION] 🟠🟠🟠🟠 extension Entity { static func createSphere(radius: Float, color: NSColor) -> Entity { let mesh = MeshResource.generateSphere(radius: radius) var material = PhysicallyBasedMaterial() material.baseColor = .init(tint: color) let modelComponent = ModelComponent(mesh: mesh, materials: [material]) let entity = Entity() entity.components.set(modelComponent) entity.components.set(Transform()) return entity } // End of [static func createSphere(radius: Float, color: NSColor) -> Entity] } // End of [extension Entity] // Application Image :: Calgary // Website Image :: timeanddate // mooncalc.org

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