POV-Ray : Newsgroups : povray.binaries.images : B-DNA : Re: B-DNA Server Time 3 Mar 2024 18:18:28 EST (-0500)
 Re: B-DNA
 From: Thomas de Groot Date: 10 Feb 2024 03:30:00 Message: <65c73408\$1@news.povray.org>
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Op 7-2-2024 om 17:35 schreef Bald Eagle:
> Thomas de Groot <tho### [at] degrootorg> wrote:
>
>> I dimly remembered an old post about Euler matrix rotations:
>>
>
> Very nice.  I'll hopefully get a chance to take a look at that code and what it
> does in the coming week.
>
Good.

> In preparation for that, I wrote a little transform visualization playground
> that compares the transformed world coordinates (basis vectors) to the camera
> basis vectors.
> (I phrase it that way, since if you apply a transform to the camera, you'll get
> the effect of transforming all of POV-space with that transform)
>
> It's also difficult for most people to grasp and clearly understand what's going
> on with a matrix transform, and keep track of how the basis vectors get
> processed, and what the values in the matrix < > (matrix vector) directive
> represent.
>
Very useful! And yes, meddling with matrix feels like (black) magic... ;-)

> So the first transform I rendered is the Shear_Trans (), since it's a straight
> conversion of the basis vector space to what's specified in the matrix vector.
> There's really no "shear" unless you specify one.
> Shear_Trans () really does nothing except apply a straight transform {matrix
> <>}.
> You can use it to shear, scale, or rotate, or all 3, depending on what values
> you put in for the arguments.  You can't do translations with it, since that
> last row vector is hard-coded in the macro to 0, 0, 0.
>
Excellent initiative! Going to put that into my HowTo folder, and play
with it as soon as I can find a few free seconds of time.

--
Thomas
```