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From: Ullrich Koethe (koethe_at_[hidden])
Date: 2006-10-19 12:41:01
Joel de Guzman wrote:
>>
>>I had a look at Fusion, but I'm not sure whether it would be helpful in
>>this context. TinyVector is based on three design goals: it should support
>>the std::vector interface (except for resize etc.),
>
>
> Like boost::array?
>
Similar, but more sophisticated. E.g. it has separate view templates that
don't own the data, and provides a number of mathematical functions with
loop unrolling.
>>like a built-in arithmetic type (except for division which is problematic
>>because the zero vector is not the only one that may cause a
>>division-by-zero error).
>
>
> No problem. But have you seen Andy's work on matrices using fusion?
>
No, can you provide a pointer?
>> Fusion may be more helpful in heterogeneous pixel
>>types, but they often have very specific requirements that are perhaps
>>better handled explicitly.
>
>
> Like what, for example?
>
How about RGBA? How would a Fusion version of alpha blending two pixels
look like? The formula is
RGB' = alpha2*RGB2 + (1-alpha2)*alpha1*RGB1
alpha' = alpha2 + (1-alpha2)*alpha1
where pixel 2 is in front of pixel 1. Alternatively, with premultiplied
alpha we have
RGBA' = RGBA2 + (1-alpha2)*RGBA1
When the individual channels are represented by uint8, we must add
functionality to stay in the range 0...255.
Regards
Ulli
-- ________________________________________________________________ | | | Ullrich Koethe Universitaet Hamburg / University of Hamburg | | FB Informatik / Dept. of Informatics | | AB Kognitive Systeme / Cognitive Systems Group | | | | Phone: +49 (0)40 42883-2573 Vogt-Koelln-Str. 30 | | Fax: +49 (0)40 42883-2572 D - 22527 Hamburg | | Email: u.koethe_at_[hidden] Germany | | koethe_at_[hidden] | | WWW: http://kogs-www.informatik.uni-hamburg.de/~koethe/ | |________________________________________________________________|
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