Can't load large jpeg into a MTLTexture with MTKTextureLoader

Question

I'm trying to load a large image into a MTLTexture and it works with 4000x6000 images. But when I try with 6000x8000 it can't.

func setTexture(device: MTLDevice, imageName: String) -> MTLTexture? {
        let textureLoader = MTKTextureLoader(device: device)
        
        var texture: MTLTexture? = nil
        
        //  In iOS 10 the origin was changed.
        let textureLoaderOptions: [MTKTextureLoader.Option: Any]
        if #available(iOS 10.0, *) {
            let origin = MTKTextureLoader.Origin.bottomLeft.rawValue
            textureLoaderOptions = [MTKTextureLoader.Option.origin : origin]
        } else {
            textureLoaderOptions = [:]
        }
        
        if let textureURL = Bundle.main.url(forResource: imageName, withExtension: nil, subdirectory: "Images") {
            do {
                texture = try textureLoader.newTexture(URL: textureURL, options: textureLoaderOptions)
            } catch {
                print("Texture not created.")
            }
        }
        return texture
    }

Pretty basic code. I'm running it in an iPad Pro with A9 chip, GPU family 3. It should handle textures this large. Should I manually tile it somehow if it doesn't accept this size? In that case, what's the best approach: using MTLRegionMake to copy bytes, slicing in Core Image or a Core Graphics context...

I appreciate any help

Answer 1

Following your helpful comments I decided to load it manually drawing to a CGContext and copying to a MTLTexture. I'm adding the solution code below. The context shouldn't be created each time a texture is created, it's better to put it outside the function and keep reusing it.

// Grab the CGImage, w = width, h = height...
    
let context = CGContext(data: nil, width: w, height: h, bitsPerComponent: bpc, bytesPerRow: (bpp / 8) * w, space: colorSpace!, bitmapInfo: bitmapInfo.rawValue)
        
let flip = CGAffineTransform(a: 1, b: 0, c: 0, d: -1, tx: 0, ty: CGFloat(h))
context?.concatenate(flip)
context?.draw(cgImage, in: CGRect(x: 0, y: 0, width: CGFloat(w), height: CGFloat(h)))
        
let textureDescriptor = MTLTextureDescriptor()
textureDescriptor.pixelFormat = .rgba8Unorm
textureDescriptor.width = w
textureDescriptor.height = h
        
guard let data = context?.data else {print("No data in context."); return nil}
        
let texture = device.makeTexture(descriptor: textureDescriptor)
texture?.replace(region: MTLRegionMake2D(0, 0, w, h), mipmapLevel: 0, withBytes: data, bytesPerRow: 4 * w)
        
return texture