Re: [GLM Devel] swizzle operations using unions

[Christophe R. <chr...@gm...>]

Hi,

I was just having a look at these new problems and I notice that you change
in your code the union by struct. Is there any reason for it? I was
considering the same thing to be able to specialize the vec<half> which
can't be union.

This union with no constructor has always been a pain in all my experiments
to implement a good swizzle operator and I haven't found any answer yet. I'm
afraid this will remain a critical issue :/

 I still didn't had time to really tackle the subject but if everything goes
well, it will have been the case within a week.

Christophe

On 28 May 2010 16:46, Christoph Schied <Chr...@un...> wrote:

> Hi,
>
> I continued playing with the swizzle stuff and just encountered a major
> problem which I wasn't aware of:
>  vec3 v1, v2;
>  v1.xy = v2.xy;
>
> This calls the default assignment constructor for attrib_alias_vec2
> which won't do anything as attrib_alias has no members. This cannot be
> solved as C++ does not allow a member of a union to have a non-default
> constructor. This also includes T & operator=(const T &t). The only
> solution is to make the left and right side of the assignment different
> types, but i don't know how one could create a template which has a
> different type in each instantiation (and i don't think this would be a
> nice thing). One solution is to make the different swizzle indizes of
> different types, and as such make at least the following work:
>  vec3 v1, v2;
>  v1.rg = v2.xy;
> The problem still is that one can't even declare the default-constructor
> private, so one cannot create an error.
>
> Any ideas how this could be solved?
>
> greetings,
>        Christoph
>
>
>
> ------------------------------------------------------------------------------
>
> _______________________________________________
> ogl-math-devel mailing list
> ogl...@li...
> https://lists.sourceforge.net/lists/listinfo/ogl-math-devel
>