[PD] [Gem] Alpha: transparency only in one direction?

[chris clepper]

On 12/1/05, Roman Haefeli <reduzierer at yahoo.de> wrote:
> sorry for my language.
> i see that one can change the execution order dynamically, but this
> doesn't help in the case when two rectangles cross each other (like an
> 'X'). then you have at the same time the first AND the second rendered
> rectangle in front, but only one part is transparent.
>
> roman

You need 4 rectangles to do that properly.  This is one of the oldest
problems in 3D rendering.