> For the complete documentation index, see [llms.txt](https://trizen.gitbook.io/sidef-lang/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://trizen.gitbook.io/sidef-lang/programming_tasks/c/color_wheel.md).

# Color wheel

```ruby
require('Imager')

var (width, height) = (300, 300)
var center = Complex(width/2 , height/2)

var img = %O<Imager>.new(xsize => width, ysize => height)

for y=(^height), x=(^width) {
    var vector    = (center - x - y.i)
    var magnitude = (vector.abs * 2 / width)
    var direction = ((Num.pi + atan2(vector.real, vector.imag)) / Num.tau)
    img.setpixel(x => x, y => y,
        color => Hash(hsv => [360*direction, magnitude, magnitude < 1 ? 1 : 0])
    )
}

img.write(file => 'color_wheel.png')
```

[Output image](https://github.com/trizen/rc/blob/master/img/color-wheel-sidef.png)