"Bald Eagle" <cre### [at] netscapenet> wrote:
> Thomas de Groot <tho### [at] degrootorg> wrote:
>
> > Just for now, a very /basic/ wish for the new Moray, one that every
> > Moray user will approve I am sure:
> >
> >
> > * Make the GUI /left-handed/ instead of /right-handed/. *
>
> I approve in the sense that I disapprove of locking the users into exactly the
> opposite basis vectors.
>
> If we would like to make the New Moray something useful and enduring, then I
> would say that if all of the operations proceed from first principles, assuming
> virtually nothing, then all of the operations can be generalized and it will be
> as flexible and trouble-free as we can manage, possibly allowing things we might
> not imagine when building it.
>
> 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

Reserve left-hand/ right-hand is better indeed.

I cannot figure out what is "where the x, y, and z vectors can be specified like
in a matrix {}"

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

> I cannot figure out what is "where the x, y, and z vectors can be specified like
> in a matrix {}"

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

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"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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