[PD] GEM: texturing parts of multiple movies

[simon wise]

On 22 Jan 2008, at 11:03 PM, Georg Holzmann wrote:

> Hallo!
>
> I have the following (basic) GEM problem (and some ascii-art ;) :
>
> I have 2 movies running with pix_film which are rendered on rectangles
> with the same size over the whole screen and I want to see only a part
> of each movie (see illustration):
>
> from movie A:
> -------------------------------
> |                             |
> |                             |
> |                             |
> |  |-------|                  |
> |  | partA |                  |
> |  |       |                  |
> |  |-------|                  |
> -------------------------------
> from movie B:
> -------------------------------
> |                |--------|   |
> |                | partB  |   |
> |                |        |   |
> |                |--------|   |
> |                             |
> |                             |
> |                             |
> -------------------------------
> together:
> -------------------------------
> |                |--------|   |
> |                | partB  |   |
> |                |(movieB)|   |
> |  |-------|     |--------|   |
> |  | partA |                  |
> |  |(movieA|                  |
> |  |-------|                  |
> -------------------------------
>
> So I tried to lay black rectangles over the movies and let free
> partA,partB so that one can only see these parts. But this does not  
> work
> for multiple movies, because then I only see the movie with the  
> highest
> gemhead priority (and also with alpha blending it was not  
> possible) ...
>
> So my question: is this possible without additional pix_* commands ?
> (e.g. texturing only a part of the movie onto a rectangle ... ?)
> If yes has someone an idea how ?
>
> Thanks for any hint,
> LG
> Georg
>
> PS: if this is too confusing I can send an example patch ;)
>
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a somewhat clumsy workaround would be to make a transparent rectangle  
the size of part A, in front of the others in space, then movie B  
with the black masks behind that, then movie A behind that:

set your gemwin to 'orthagonal'

set the render order of the oblects:

movie A first
part A second
movie B with masks etc next


but there is probably also a way to render part of the image, I'd  
like to know also



simon