barbulescualex

func draw(in view: MTKView) {
    //create command buffer for ciContext to use to encode it's rendering instructions to our GPU
    guard let commandBuffer = metalCommandQueue.makeCommandBuffer() else {
        return
    }

    //make sure we actually have a ciImage to work with
    guard var ciImage = currentCIImage else {
        return
    }

barbulescualex

func draw(in view: MTKView) {
    var r = view.bounds
    r.size = view.drawableSize
    let scaleX = r.size.height/outputCIImage.extent.size.height
    let transform = CGAffineTransform(scaleX: scaleX, y: scaleX)
    outputCIImage = outputCIImage.transformed(by: transform)
    outputCIImage = outputCIImage.cropped(to: r)
    let x = -r.origin.x
    let y = -r.origin.y

barbulescualex

extension ViewController {
    //MARK:- View Setup
    func setupView(){
        view.backgroundColor = .black
        mtkView.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(mtkView)
        view.addSubview(switchCameraButton)
        view.addSubview(captureImageButton)
        view.addSubview(capturedImageView)

barbulescualex

import UIKit
import AVFoundation
import MetalKit

class ViewController: UIViewController {
    
    ...
    
    //MARK:- View Components
     

barbulescualex

func switchCameraInput(){
    //don't let user spam the button, fun for the user, not fun for performance
    switchCameraButton.isUserInteractionEnabled = false

    //reconfigure the input
    captureSession.beginConfiguration()
    if backCameraOn {
        captureSession.removeInput(backInput)
        captureSession.addInput(frontInput)
        backCameraOn = false

barbulescualex

class ViewController: UIViewController {
    
    ...
    
    let fadeFilter = CIFilter(name: "CIPhotoEffectFade")
    let sepiaFilter = CIFilter(name: "CISepiaTone")
    
    ...
    
    //MARK:- Core Image

barbulescualex

extension ViewController : MTKViewDelegate {
    func mtkView(_ view: MTKView, drawableSizeWillChange size: CGSize) {
        //tells us the drawable's size has changed
    }
    
    func draw(in view: MTKView) {
        //create command buffer for ciContext to use to encode it's rendering instructions to our GPU
        guard let commandBuffer = metalCommandQueue.makeCommandBuffer() else {
            return
        }

barbulescualex

class ViewController: UIViewController {
    
    ...
    
    //core image
    var currentCIImage : CIImage?
    
    ...
  
    //MARK:- Metal

barbulescualex

class ViewController: UIViewController {
    
    ...
  
    //core image
    var ciContext : CIContext!
    
    ...
    
    override func viewDidAppear(_ animated: Bool) {

barbulescualex

class ViewController: UIViewController {
    
    ...
    
    func setupMetal(){
        //fetch the default gpu of the device (only one on iOS devices)
        metalDevice = MTLCreateSystemDefaultDevice()
        
        //tell our MTKView which gpu to use
        mtkView.device = metalDevice