[PD] GEM: texturing parts of multiple movies

simon wise simonxwise at hotmail.com
Tue Jan 22 14:07:44 CET 2008


On 22 Jan 2008, at 11:41 PM, simon wise wrote:

>
> 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

I replied too quickly,

a better (more general solution which could involve more movies and  
no masking) would be:

set the gemwin 'orthagonal'
layer the movies so A is furthest away, then B, C etc
in front of this place a black rectangle
then transparent rectangles part A, B C etc

render order is:
movie A
then part A
then movie B
then part B
then movie C
then part C
etc
finally render the black rectangle


this way you can easily move the part around


simon






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