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

Subject: [ggl] Efficient rotation about a point
From: Barend Gehrels (Barend.Gehrels)
Date: 2009-12-02 03:54:47

Hi Lee,

> 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?

We don't want to duplicate functionality from uBlas or another matrix 
library, but use it.

I agree that the rotate/scale/translate might not be that useful. 
However, they are tiny derivatives from ublas_transformer, only calling 
its constructor. The ublas_transformer has a constructor taking 9 
values, so you call it also yourself. And we'll add a constructor taking 
a matrix.

The ublas transformers are not the only things, the generic design is 
that the generic "transform" function take a strategy (which can be a 
matrix, but also a projection, or anything you create yourself).

Regards, Barend