Get Color of point in a SKScene swift

Question

I need to get the color of a pixel/point for my game in Swift. So I tried to find a function that inputs a CGPoint and returns a Color, everything that I have found so far has only returned (0,0,0,0). I think that this is because I am doing this in my game scene class(which is an SKScene), and the scene is only being loaded by a view controller. Any Solutions?

(If there is a better way to check if a sprite is touching a color that would work as well)

Thanks in advance.

http://stackoverflow.com/questions/1160229/how-to-get-the-color-of-a-pixel-in-an-uiview has code for Swift 2 and 3: http://stackoverflow.com/a/26945594/1187415 — Martin R, Mar 09 '17 at 06:11
@MartinR these solutions seem to only return transparency/black as well — joshLor, Mar 09 '17 at 07:03
depends on when/how you are getting it. Scene and View are 2 different things entirely, so your coordinate in scene may not reflect your coordinate in the view, plus the contents may not be rendered to the context till after it is drawn. On top of this you need to worry about retina, which could also lead to an invalid pixel. Perhaps the real question is, why do you need an individual point, and is there a better alternative? — Knight0fDragon, Mar 09 '17 at 12:54
I need to be able to check if my object is colliding with a color. Any other way of doing that would be fine but it has to work with spriteKit and in my game scene. — joshLor, Mar 09 '17 at 14:54
@Knight0fDragon do you have any ideas? I updated my question a bit. — joshLor, Mar 09 '17 at 17:42
What are we talking about here, black square hitting blue circle — Knight0fDragon, Mar 09 '17 at 17:45
@Knight0fDragon I have a circle that collides with a color wheel and I want to get what color it hits (both are SKSpritenodes ) — joshLor, Mar 09 '17 at 17:50
then I would make your color wheel several sprites contained in 1 big node, this way you can distinguish from each segment — Knight0fDragon, Mar 09 '17 at 19:06
basically each color segment of the color wheel is a sprite (Assuming this is wheel of fortune / pizza slice style color wheel and not a spiral) — Knight0fDragon, Mar 09 '17 at 19:07

score 5 · Accepted Answer · edited Mar 09 '17 at 05:31

5

Add the below method:

extension UIView {
    func getColor(at point: CGPoint) -> UIColor{

        let pixel = UnsafeMutablePointer<CUnsignedChar>.allocate(capacity: 4)
        let colorSpace = CGColorSpaceCreateDeviceRGB()
        let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.premultipliedLast.rawValue)
        let context = CGContext(data: pixel, width: 1, height: 1, bitsPerComponent: 8, bytesPerRow: 4, space: colorSpace, bitmapInfo: bitmapInfo.rawValue)!

        context.translateBy(x: -point.x, y: -point.y)
        self.layer.render(in: context)
        let color = UIColor(red:   CGFloat(pixel[0]) / 255.0,
                            green: CGFloat(pixel[1]) / 255.0,
                            blue:  CGFloat(pixel[2]) / 255.0,
                            alpha: CGFloat(pixel[3]) / 255.0)

        pixel.deallocate(capacity: 4)
        return color
    }
}

You can get the color of the point you want with

let color = someView.getColor(at: somePoint)

edited Mar 09 '17 at 05:31

Alexander

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answered Mar 09 '17 at 05:18

Parth Adroja

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This would be awesome as an extension of `UIView` – Alexander Mar 09 '17 at 05:26
@Alexander It would be great to have extension. Feel free to edit if you would like to. – Parth Adroja Mar 09 '17 at 05:28
Take a look :D it's beautiful! – Alexander Mar 09 '17 at 05:31
@Alexander Thanks – Parth Adroja Mar 09 '17 at 05:32
1

when I test out the code it always returns black(0,0,0,0) – joshLor Mar 09 '17 at 06:33
3

The original version of your answer looks like a *verbatim copy* of the code in http://stackoverflow.com/a/34461183/1187415, without attribution. – Martin R Mar 09 '17 at 06:36
@MartinR I don't remember but I have taken the code from StackOverflow. I have this in my code snippet. – Parth Adroja Mar 09 '17 at 06:41
what could possible reasons be for this. Is it because there is an error – joshLor Mar 09 '17 at 06:43
btw the UiView that I am using is simply self.view (self being my view controller) – joshLor Mar 09 '17 at 06:44
There is nothing really different to my code. The only weird thing may be that the image in my scene has a transparent background. – joshLor Mar 09 '17 at 06:47
@joshLor Might be that's the issue. Please assign the background color to view and check if its giving you the appropriate color. If it does then need to improve code to take the color from image not the view. – Parth Adroja Mar 09 '17 at 06:52
nope, I tried everything including taking out my image all together, it could not even sense the backgrounds color. – joshLor Mar 09 '17 at 06:55
Thank you so much for this clear and up-to-date Swift answer! (hopefully it still is up-to-date when the next person reads this ;) ) – Alex Bollbach Apr 19 '17 at 23:37

Get Color of point in a SKScene swift

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