ARKitTestDemo/ARTest/ViewController.swift

//
//  Copyright (c) 2017 Touch Instinct
//
//  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 UIKit
import SceneKit
import ARKit

private enum GameState {
    case placing
    case shootting
}

final class ViewController: UIViewController, ARSCNViewDelegate {

    // MARK: - Constants

    private static let logoMaxCount = 3
    private static let cameraToLogoSpace: Float = -1

    // MARK: - IBOutlets

    @IBOutlet private weak var sceneView: ARSCNView!
    @IBOutlet private weak var timeLabel: UILabel!
    @IBOutlet private weak var scoreLabel: UILabel!
    @IBOutlet private weak var prizelImageView: UIImageView!

    // MARK: - Properties

    fileprivate var state: GameState = .placing {
        didSet {
            prizelImageView.isHidden = state == .placing
        }
    }
    fileprivate var logoCount = 0 {
        didSet {
            DispatchQueue.main.async {
                self.scoreLabel.text = "\(self.logoCount)"
            }
        }
    }
    fileprivate var gameSeconds = 0
    fileprivate var gameTimer: Timer?

    // MARK: - ViewController life cycle

    override func viewDidLoad() {
        super.viewDidLoad()

        sceneView.scene.physicsWorld.contactDelegate = self

        // Show statistics such as fps and timing information
        sceneView.showsStatistics = true

        let tapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(tapAction))
        sceneView.addGestureRecognizer(tapGestureRecognizer)

        logoCount = 0
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)

        // Create a session configuration
        let configuration = ARSessionConfiguration.isSupported ? ARWorldTrackingSessionConfiguration()
                                                               : ARSessionConfiguration()

        // Run the view's session
        sceneView.session.run(configuration)
    }

    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)

        // Pause the view's session
        sceneView.session.pause()
        stopGame()
    }

    // MARK: - Actions

    @objc private func tapAction() {
        switch state {
        case .placing:
            addLogo()
        case .shootting:
            shoot()
        }
    }

    private func addLogo() {
        guard let currentFrame = sceneView.session.currentFrame else {
            return
        }

        let logo = Logo()
        sceneView.scene.rootNode.addChildNode(logo)

        var translation = matrix_identity_float4x4
        translation.columns.3.z = ViewController.cameraToLogoSpace
        logo.simdTransform = matrix_multiply(currentFrame.camera.transform, translation)

        logoCount += 1
        if logoCount == ViewController.logoMaxCount {
            startGame()
        }
    }

    private func shoot() {
        let arBullet = ARBullet()

        let (direction, position) = cameraVector
        arBullet.position = position

        let bulletDirection = direction
        arBullet.physicsBody?.applyForce(bulletDirection, asImpulse: true)
        sceneView.scene.rootNode.addChildNode(arBullet)
    }

}

// MARK: - Game logic

extension ViewController {

    fileprivate func startGame() {
        state = .shootting

        gameTimer = Timer.scheduledTimer(withTimeInterval: 1, repeats: true, block: { [weak self] _ in
            self?.gameSeconds += 1
            DispatchQueue.main.async {
                self?.configureTimeLabel()
            }
        })
    }

    fileprivate func stopGame() {
        state = .placing

        gameTimer?.invalidate()
        gameTimer = nil

        gameSeconds = 0
        logoCount = 0

        configureTimeLabel()
    }

    fileprivate func configureTimeLabel() {
        timeLabel.isHidden = self.gameSeconds == 0

        let seconds = self.gameSeconds % 60
        let minutes = (self.gameSeconds / 60) % 60

        timeLabel.text = String(format: "%02d:%02d", minutes, seconds)
    }

}

// MARK: - Utils

extension ViewController {

    fileprivate var cameraVector: (SCNVector3, SCNVector3) { // (direction, position)
        if let frame = self.sceneView.session.currentFrame {
            let mat = SCNMatrix4FromMat4(frame.camera.transform) // 4x4 transform matrix describing camera in world space
            let dir = SCNVector3(-1 * mat.m31, -1 * mat.m32, -1 * mat.m33) // orientation of camera in world space
            let pos = SCNVector3(mat.m41, mat.m42, mat.m43) // location of camera in world space

            return (dir, pos)
        }
        return (SCNVector3(0, 0, 0), SCNVector3(0, 0, 0))
    }

}

// MARK: - SCNPhysicsContactDelegate

extension ViewController: SCNPhysicsContactDelegate {

    func physicsWorld(_ world: SCNPhysicsWorld, didBegin contact: SCNPhysicsContact) {
        guard let nodeABitMask = contact.nodeA.physicsBody?.categoryBitMask,
            let nodeBBitMask = contact.nodeB.physicsBody?.categoryBitMask,
            nodeABitMask & nodeBBitMask == CollisionCategory.logos.rawValue & CollisionCategory.arBullets.rawValue else {
                return
        }

        contact.nodeB.removeFromParentNode()
        logoCount -= 1

        if logoCount == 0 {
            DispatchQueue.main.async {
                self.stopGame()
            }
        }

        DispatchQueue.main.asyncAfter(deadline: .now() + 0.5, execute: {
            contact.nodeA.removeFromParentNode()
        })
    }

}