colour lib needs reviewers

[Manu via Digitalmars-d]

On 13 September 2016 at 17:47, John Colvin via Digitalmars-d
<digitalmars-d at puremagic.com> wrote:
> On Tuesday, 13 September 2016 at 01:05:56 UTC, Manu wrote:
>>>
>>> Also can I swizzle channels directly?
>>
>>
>> I could add something like:
>>   auto brg =  c.swizzle!"brg";
>>
>> The result would be strongly typed to the new arrangement.
>
>
> Perfect use-case for opDispatch like in gl3n.

One trouble with arbitrary swizzling is that people often want to
write expressions like "c.xyzy", or whatever, but repeating
components... and that's not something my colours can do. It's useful
in realtime code, but it doesn't mean anything, and you can't
interpret that value as a colour anymore after you do that.
This sort of thing is used when you're not actually storing colours in
textures, but instead just some arbitrary data. Don't use a colour
type for that, use a vector type instead.
What that sort of swizzling really is, are vector operations, not
colour operations. Maybe I could add an API to populate a vector from
the components of colours, in-order... but then we don't actually have
linear algebra functions in phobos either! So colour->vectors and
arbitrary swizzling is probably not something we need immediately.

In my lib, colours are colours. If you have `BGR8 x` and `RGB8 y`, and
add them, you don't get x.b+y.r, x.g+y.g, x.r+y.b... that's not a
colour operation, that's an element-wise vector operation.