Metal每日分享，调节亮度滤镜效果

// 调节亮度滤镜
let filter = C7Brightness.init(brightness: 0.25)
// 方案1:
let dest = BoxxIO.init(element: originImage, filter: filter)
ImageView.image = try? dest.output()
dest.filters.forEach {
    NSLog("%@", "\($0.parameterDescription)")
}
// 方案2:
ImageView.image = try? originImage.make(filter: filter)
// 方案3:
ImageView.image = originImage ->> filter

public struct C7Brightness: C7FilterProtocol {
    /// The adjusted brightness, from -1.0 to 1.0, with a default of 0.0 being the original picture.
    public static let range: ParameterRange<Float, Self> = .init(min: -1.0, max: 1.0, value: 0.0)
    public var brightness: Float = range.value
    public var modifier: Modifier {
        return .compute(kernel: "C7Brightness")
    }
    public var factors: [Float] {
        return [brightness]
    }
    public init(brightness: Float = range.value) {
        self.brightness = brightness
    }
}

kernel void C7Brightness(texture2d<half, access::write> outputTexture [[texture(0)]],
                         texture2d<half, access::read> inputTexture [[texture(1)]],
                         device float *brightness [[buffer(0)]],
                         uint2 grid [[thread_position_in_grid]]) {
    const half4 inColor = inputTexture.read(grid);
    const half4 outColor = half4(inColor.rgb + half3(*brightness), inColor.a);
    outputTexture.write(outColor, grid);
}