"Bald Eagle" <cre### [at] netscapenet> wrote:
>
> When we use POV-Ray, we assume that the basis vectors for the Euclidian space we
> are modeling in, are defined as:
> x = <1, 0, 0>
> y = <0, 1, 0>
> z = <0, 0, 1>
>
> TdG points out that a "fix" or workaround for scenes made in Moray, which is
> right-handed, is to scale the camera "scale <-1, 0, 0>" in order to "flip" the
> whole scene and make it look correct.
>
> But fundamentally, what you are doing is changing the x basis vector (relatively
> speaking), which affects every point in the 3D space that you are working in,
> and therefore every object built using those coordinates.
>
> Making those basis vectors user-definable at their core would add a maximum
> flexibility.
> In fact, if one really wanted to go nuts, rather than just having scalar values
> in the matrix, one could define some sort of function to warp the entire
> coordinate space.   I know that sounds crazy, and most people will ask, "WHY
> would you want to do that???!", but watch Grant's excellent videos, and you
> might get some ideas.
>
>
> http://www.f-lohmueller.de/pov_tut/trans/trans_400e.htm
>
> Also check out Grant Sanderson's (3Blue1Brown) excellent series on linear
> algebra.
> https://www.youtube.com/watch?v=k7RM-ot2NWY


Oh, I know what thing do you said now, thank you.
What you said is about the transform associate with camera before cast to
screen...

I have basic capability with vector and matrix. But fail to understand
eigenvalue/ eigenvector / diagonal matrix

I ever derive/coding method of axis rotate by myself.

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Attachments:
Download 'vector3.png' (65 KB)

Preview of image 'vector3.png'

"And" <49341109@ntnu.edu.tw> wrote:

> Oh, I know what thing do you said now, thank you.
> What you said is about the transform associate with camera before cast to
> screen...

Yes, but it can affect more than the camera.  You can use a plain camera and
apply those types of transforms to objects or even patterns.   This is sort of
how some pigment patterns are generated, and it's also very much like
uv-mapping, parametrics, Bezier patches, etc.

One of our vectors might not be "x", but "East" as we travel around a globe.

You have your normal x, y, and z as a starting point - the standard orthogonal
unit vectors - but then traveling in the new directions does not result in
travel along the cardinal axes, or even straight lines, because you're following
the path of a different vector or parametric function.

> I have basic capability with vector and matrix. But fail to understand
> eigenvalue/ eigenvector / diagonal matrix

https://www.youtube.com/watch?v=PFDu9oVAE-g
https://www.youtube.com/watch?v=e50Bj7jn9IQ

> I ever derive/coding method of axis rotate by myself.

Yes, that's a good thing to do - the more you understand the basics, the less
mysterious the more complicated stuff seems to be.

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Op 24/11/2022 om 14:31 schreef Bald Eagle:
> Thomas de Groot <tho### [at] degrootorg> wrote:
> 
>> * Make the GUI /left-handed/ instead of /right-handed/. *
> 
> [snip]
> 
> So I say, proceed from a configuration file or control panel, where the x, y,
> and z vectors can be specified like in a matrix {}.  Then you can do whatever
> you want.   Else, I can imagine the very first thing someone somewhere will
> complain about is that they wanted to use Moray for something and - dammit - why
> is it only LEFT handed???!  Can the developers make it so I can use it right
> handed....?
> 
> Then we can see what Francois Le Coat does with it.  :D
> 

Much better than my suggestion. I fully agree with this principle!

-- 
Thomas

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"Bald Eagle" <cre### [at] netscapenet> wrote:
> "And" <49341109@ntnu.edu.tw> wrote:
>
> > I have basic capability with vector and matrix. But fail to understand
> > eigenvalue/ eigenvector / diagonal matrix
>
> https://www.youtube.com/watch?v=PFDu9oVAE-g
> https://www.youtube.com/watch?v=e50Bj7jn9IQ
>
> > I ever derive/coding method of axis rotate by myself.
>
> Yes, that's a good thing to do - the more you understand the basics, the less
> mysterious the more complicated stuff seems to be.

Thanks the youtube link. I will think them one day.

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I'm happy to see some activity around this release :-)

If there are any specific questions about Moray or design decisions or code
structure, I'm happy to answer as best I can, keeping in mind I developed it in
the late 80s and 90s and my memory isn't the best anymore. :-)

I have been using Moray still to this day to read and edit STL files for my 3D
printer, although for new designs I use Fusion 360 now.

Cheers,

- Lutz

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Hi, Lutz.

I would like to look at it, but "www.stmuc.com/moray" return:
"The requested URL was not found on this server."

Am I wrong with address ?
--
YB

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"Lutz" <lut### [at] stmuccom> wrote:
> I'm happy to see some activity around this release :-)
>
> If there are any specific questions about Moray or design decisions or code
> structure, I'm happy to answer as best I can, keeping in mind I developed it in
> the late 80s and 90s and my memory isn't the best anymore. :-)
>
> I have been using Moray still to this day to read and edit STL files for my 3D
> printer, although for new designs I use Fusion 360 now.
>
> Cheers,
>
> - Lutz

Yes Lutz is the man. As he says he developed it and it worked.
I see no reason why we can't keep the format as is for now.
What 'ancient' code has to do with anything I can't grasp at all. Surely a
program written for an older operating system can't have any clout once it's
coded to run on Win 10 or a modern Linux system.
Anyway I'm just a 'user' so my opinion my not really valid.
Great to hear that things are in motion.

Thanks

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On 11/02/2023 18:25, Lutz wrote:
> I'm happy to see some activity around this release :-)
> 
> If there are any specific questions about Moray or design decisions or code
> structure, I'm happy to answer as best I can, keeping in mind I developed it in
> the late 80s and 90s and my memory isn't the best anymore. :-)
> 
> I have been using Moray still to this day to read and edit STL files for my 3D
> printer, although for new designs I use Fusion 360 now.

Thanks Lutz! Your advice will help indeed:)

-- Chris

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