Geometry Boost List: [ggl] Efficient rotation about a point

Subject: [ggl] Efficient rotation about a point
From: Lee (lee)
Date: 2009-12-01 21:08:04

Mateusz Loskot wrote:
> Barend Gehrels wrote:
>>> Thanks Barend, Stephen.
>>>
>>> Barend, since GGL transformers aren't composable, wouldn't it be 
>>> right for GGL to provide some type of transformer taking a matrix as 
>>> its constructor parameter?
>>
>> Yes, I think that is a good idea. Will be solved (either done, or 
>> maybe they should be composable).
>
> I was thinking about it yesterday.
>
> For now, wouldn't it be sufficient to use ublas_transformer
> and enable compositions [1] with a simple custom matrix [2] in similar 
> manner as Boost.GIL does it.
>
> [1] http://www.boost.org/doc/libs/1_41_0/libs/gil/example/affine.cpp
> [2] 
> http://www.koders.com/cpp/fidEE0E20E57D2E5FCE4EE30F3AF143F5E78A7749B3.aspx 
>
>
> Best regards,
I wonder, is there really any benefit in having composable-matrix + 
ublas_transformer over having
composable (affine) transformers?

As a user, I'm looking at the existing rotate/translate/scale 
transformers and being frustrated by the
thought "if only I could compose these things!". Is matrix + 
ublas_transformer really the answer to
that?