The field of view of the ARKit device camera.

ARCamera+FieldOfView.swift

//
//  ARCamera+FieldOfView.swift
//
//  Created by Drew Olbrich on 1/3/24.
//  Copyright © 2024 Lunar Skydiving LLC. All rights reserved.
//
//  MIT License
//  
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the Software is
//  furnished to do so, subject to the following conditions:
//  
//  The above copyright notice and this permission notice shall be included in all
//  copies or substantial portions of the Software.
//  
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
//  SOFTWARE.
//

import ARKit

extension ARCamera {
    
    /// The horizontal and vertical field of view of the device's camera, in radians.
    ///
    /// These values reflect the dimensions of the device's camera, which always has
    /// landscape orientation, regardless of the physical orientation of the device.
    /// They do not necessarily reflect the dimensions or orientation of the AR view
    /// that the camera image is displayed in.
    var deviceFieldOfView: (Float, Float) {
        // From https://stackoverflow.com/a/47643149/2419404        
        let xFieldOfViewRadians = 2*atan(Float(imageResolution.width)/(2*intrinsics[0, 0]))
        let yFieldOfViewRadians = 2*atan(Float(imageResolution.height)/(2*intrinsics[1, 1]))
        return (xFieldOfViewRadians, yFieldOfViewRadians)
    }
    
}