Reading the first row/column/channel

[yeldarby]

I may be misunderstanding but shouldn't all of these preconditions be _ >= 0 instead of _ > 0? Otherwise how do you read the first row/column/channel? image[0, 0, 0] returns an error.

https://github.com/SwiftGL/Image/blob/master/Sources/SGLImage/Image.swift#L128

public subscript(x:Int, y:Int, channel:Int) -> T {
        get {
            precondition(x > 0 && x < width)
            precondition(y > 0 && y < height)
            precondition(channel > 0 && channel < channels)
            return buffer[channel + x * channels + y * width * channels]
        }
        set {
            precondition(x > 0 && x < width)
            precondition(y > 0 && y < height)
            precondition(channel > 0 && channel < channels)
            buffer[channel + x * channels + y * width * channels] = newValue
        }
    }

[yeldarby]

(Oops, accidentally submitted the pull request to my own branch rather than here which closed the issue)