Color of pixel in ARSCNView - swift

Question

I am trying to get the color of a pixel at a CGPoint determined by the location of a touch. I have tried the following code but the color value is incorrect.
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
if let touch = event?.allTouches?.first {
let loc:CGPoint = touch.location(in: touch.view)
// in debugger, the image is correct
let image = sceneView.snapshot()
guard let color = image[Int(loc.x), Int(loc.y)] else{
return
}
print(color)
}
}
....
extension UIImage {
subscript (x: Int, y: Int) -> [UInt8]? {
if x < 0 || x > Int(size.width) || y < 0 || y > Int(size.height) {
return nil
}
let provider = self.cgImage!.dataProvider
let providerData = provider!.data
let data = CFDataGetBytePtr(providerData)
let numberOfComponents = 4
let pixelData = ((Int(size.width) * y) + x) * numberOfComponents
let r = data![pixelData]
let g = data![pixelData + 1]
let b = data![pixelData + 2]
return [r, g, b]
}
}
Running this and touching a spot on the screen that is a very large consistent bright orange yields a wide range of RGB values and looking at the color they actually produce yields a completely different color (dark blue in the case of the orange).
I'm guessing that maybe the coordinate systems are different and I'm actually getting a different point on the image possibly?
EDIT: Also I should mention that the part I'm tapping on is a 3D model that is not affected by lighting so the color should and appears to be consistent through run time.

Answer 1

Well it was easier than I thought. I first adjusted some things like making the touch be registered within my sceneview instead:
let loc:CGPoint = touch.location(in: sceneView)
I then reproportioned my cgpoint to adjust to the image view by doing the following:
let image = sceneView.snapshot()
let x = image.size.width / sceneView.frame.size.width
let y = image.size.height / sceneView.frame.size.height
guard let color = image[Int(x * loc.x), Int(y * loc.y)] else{
return
}
This allowed me to have consistent rgb values finally (not just numbers that changed on every touch even if I was on the same color). But the values were still off. For some reason my returned array was in reverse so I changed that with:
let b = data![pixelData]
let g = data![pixelData + 1]
let r = data![pixelData + 2]
I'm not sure why I had to do that last part, so any insight into that would be appreciated!