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From: Thomas de Groot
Subject: Bronze Age sword - take 1
Date: 13 Jul 2023 03:53:02
Message: <64afad5e@news.povray.org>
Not yet entirely satisfying but this is a first acceptable model of a 
(leaf-shaped) cast-bronze /blade/. Texture based on an example by Tim 
Attwood.

I modelled one quarter of the blade which is then mirrored 3x.

The sword's grip will be modelled over the blade, more or less how this 
was done at the time.

-- 
Thomas


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From: Thomas de Groot
Subject: Re: Bronze Age sword - take 1
Date: 13 Jul 2023 11:12:33
Message: <64b01461@news.povray.org>
A bit of improvements.

The bronze texture used is given here (for POV versions 3.7 or better 3.8):

//-------------------------------------------------
//from  https://en.wikipedia.org/wiki/Bronze_(color)
#declare P_bronze1 = rgb <205/255, 127/255, 50/255>;  //is: HTML/CSS 
#CD7F32 code. see also: https://htmlcolorcodes.com/colors/bronze/
#declare P_bronze2 = rgb <150/255, 116/255, 68/255>;  //is: Hex Color: 
#967444. see: https://colorcodes.io/brown/bronze-color-codes/
                                                       //with variations:
#declare P_bronze3 = rgb <87/255, 67/255, 39/255>;    //#574327
#declare P_bronze4 = rgb <227/255, 175/255, 102/255>; //#E3AF66
#declare P_bronze5 = rgb <163/255, 126/255, 73/255>;  //#A37E49
#declare P_bronze6 = rgb <125/255, 96/255, 56/255>;   //#7D6038

#declare P_BlastOff_bronze = rgb <165/255, 113/255, 100/255>;  //Crayola
#declare P_Antique_bronze = srgb <102/255, 93/255, 30/255>;
//My bronze:
#declare P_My_bronze = rgb <242/255, 221/255, 137/255>;

// Based on texture CastMetal by Tim Attwood
#declare CastBronze =
texture {
   pigment {P_bronze4}
   normal {granite bump_size 0.01 scale 0.01}
   finish {
     diffuse  0.01	
     brilliance 1	
     metallic on
     specular  0.6
     roughness 0.01
     reflection {0.001, 0.6 metallic on }
     conserve_energy
   }
}
//-------------------------------------------------



-- 
Thomas


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From: kurtz le pirate
Subject: Re: Bronze Age sword - take 1
Date: 14 Jul 2023 03:23:13
Message: <64b0f7e1$1@news.povray.org>
On 13/07/2023 17:12, Thomas de Groot wrote:
> A bit of improvements.
> 
> The bronze texture used is given here (for POV versions 3.7 or better 3.8):
> snip 
> 

A small remark for lazy people like me, it's shorter to write
<a,b,c>/255 rather than <a/255, b/255, c/255>...

That said, the geometry is excellent



-- 
Kurtz le pirate
Compagnie de la Banquise


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From: Thomas de Groot
Subject: Re: Bronze Age sword - take 1
Date: 14 Jul 2023 07:34:14
Message: <64b132b6$1@news.povray.org>
Op 14-7-2023 om 09:23 schreef kurtz le pirate:
> On 13/07/2023 17:12, Thomas de Groot wrote:
>> A bit of improvements.
>>
>> The bronze texture used is given here (for POV versions 3.7 or better 3.8):
>> snip
>>
> 
> A small remark for lazy people like me, it's shorter to write
> <a,b,c>/255 rather than <a/255, b/255, c/255>...
> 
I know. ;-)
However, I seem to remember that Clipka once told us that - especially 
when srgb is involved (not here directly, though) - it would be wiser to 
write it like I did here. So, being an obedient pupil, I followed 
(blindly) his advise. :-)
That said, I happen very often to be lazy too...

> That said, the geometry is excellent
> 
Thank you sir! Trying to continue in the same vein.

-- 
Thomas


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From: Cousin Ricky
Subject: Re: Bronze Age sword - take 1
Date: 14 Jul 2023 09:04:10
Message: <64b147ca$1@news.povray.org>
On 2023-07-14 07:34 (-4), Thomas de Groot wrote:
> Op 14-7-2023 om 09:23 schreef kurtz le pirate:
>>
>> A small remark for lazy people like me, it's shorter to write
>> <a,b,c>/255 rather than <a/255, b/255, c/255>...
>>
> I know. ;-)
> However, I seem to remember that Clipka once told us that - especially
> when srgb is involved (not here directly, though) - it would be wiser to
> write it like I did here. So, being an obedient pupil, I followed
> (blindly) his advise. :-)

You remember incorrectly (again).

https://news.povray.org/6065d1ea%241%40news.povray.org


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From: Thomas de Groot
Subject: Re: Bronze Age sword - take 1
Date: 14 Jul 2023 10:12:36
Message: <64b157d4$1@news.povray.org>
Op 14-7-2023 om 15:04 schreef Cousin Ricky:
> You remember incorrectly (again).
> 
> https://news.povray.org/6065d1ea%241%40news.povray.org
>


WHY am I not surprised?!?  :-)

-- 
Thomas


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From: Thomas de Groot
Subject: Re: Bronze Age sword - take 1
Date: 14 Jul 2023 10:26:59
Message: <64b15b33$1@news.povray.org>
Op 14-7-2023 om 16:12 schreef Thomas de Groot:
> WHY am I not surprised?!?  :-)
> 

It all relates to the following discussion:

http://news.povray.org/povray.general/thread/%3Cweb.60649d9bb9b7dccdd98418916e066e29%40news.povray.org%3E/?mtop=433443

Where I probably lost track, not really understanding the matter. Only 
flotsam survived on the waves of my memory...

[to self: I need to re-read this...]

-- 
Thomas


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From: Bald Eagle
Subject: Re: Bronze Age sword - take 1
Date: 14 Jul 2023 13:45:00
Message: <web.64b18904b039fa5d1f9dae3025979125@news.povray.org>
Cousin Ricky <ric### [at] yahoocom> wrote:
> On 2023-07-14 07:34 (-4), Thomas de Groot wrote:
> > Op 14-7-2023 om 09:23 schreef kurtz le pirate:
> >>
> >> A small remark for lazy people like me, it's shorter to write
> >> <a,b,c>/255 rather than <a/255, b/255, c/255>...
> >>
> > I know. ;-)
> > However, I seem to remember that Clipka once told us that - especially
> > when srgb is involved (not here directly, though) - it would be wiser to
> > write it like I did here. So, being an obedient pupil, I followed
> > (blindly) his advise. :-)
>
> You remember incorrectly (again).
>
> https://news.povray.org/6065d1ea%241%40news.povray.org

Ooooooh.  Thomas made a naughty.   :O

I'd say that since we're 30+ years in, maybe we ought to have a macro of some
sort with plenty of explanatory documentation IN the macro code.

#macro SRGB (byteTriplet, optional Multiplier)

 // Converts a byte value <0-255, 0-255, 0-255> to a
 // POV-Ray compliant rgb color vector <0-1, 0-1, 0-1>

 // Usage: SRGB (<r, g, b>)
 // - or -
 //   SRGB (<r, g, b>) * Multiplier

 // From: Cousin Ricky
 // Subject: Re: strange problem with srgb color in light_source
 // https://news.povray.org/606cb0f5%40news.povray.org
 // Here is the general sequence:
 /*
 1. An sRGB triplet that comes from a color picker, eyedropper tool, or
    published Web source is typically in the range <0,0,0> ...
    <255,255,255>.  Divide this by 255 to bring it into the range
    <0,0,0> ... <1,1,1>.  This /must/ be done first thing, and is the
    only math that should ever be done at this stage, though it may be
    combined with step 2.
 */

 #local srgbColorVector = byteTriplet/255;

 /*
 2. #declare the color with the srgb keyword.  The resulting identifier
    contains a linear color.
 */

 #local RGBcolor = srgb srgbColorVector;

 /*
 3. Now, do whatever additional math you need on the identifier.  You may
    do this in a pigment or light_source or wherever.
 */

 // ^^^ leave this for outside of the macro

 RGBcolor

#end


This, as just a simple prototype.
Something better that takes all the information (filter, transmit, multipliers)
would be nice, and would have sanity checks for out of range values, negative
values, etc.

Maybe I need to go back to the scenes where I was working out the srgb math and
use that to make a documentation infographic, and possibly an animation.

It would be way better to have a nice, fully presented thing in the distribution
that lays out all of the whys and hows, than to have to rehash this topic ever
few years.

Than people can visually and mathematically see what the byte triplet values
are, the in-range nonlinear srgb values are, the in-range linear rgb values, and
how they all relate to one another.   Just do a simple animation from <0, 0, 0>
to <255, 255, 255>, and I think that might very well cover it.
Some examples that simultaneously show the incorrect way to convert from srgb to
rgb would likely be helpful as well.

- BW


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From: Mike Miller
Subject: Re: Bronze Age sword - take 1
Date: 15 Jul 2023 00:05:00
Message: <web.64b21a1bb039fa5db5177e91dabc9342@news.povray.org>
Thomas de Groot <tho### [at] degrootorg> wrote:
> Not yet entirely satisfying but this is a first acceptable model of a
> (leaf-shaped) cast-bronze /blade/. Texture based on an example by Tim
> Attwood.
>
> I modelled one quarter of the blade which is then mirrored 3x.
>
> The sword's grip will be modelled over the blade, more or less how this
> was done at the time.
>
> --
> Thomas

Nice Job! love the model and material.
Miller


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From: Thomas de Groot
Subject: Re: Bronze Age sword - take 1
Date: 15 Jul 2023 02:21:45
Message: <64b23af9$1@news.povray.org>
Op 14/07/2023 om 19:42 schreef Bald Eagle:
> Ooooooh.  Thomas made a naughty.   :O
> 
Yeaahh.... What did you expect?  ;-)

> I'd say that since we're 30+ years in, maybe we ought to have a macro of some
> sort with plenty of explanatory documentation IN the macro code.
> 
That would be a very good idea indeed. I have been wandering around for 
some time with the same and slowly started to add comprehensive (?) 
comments to those macros or includes I use most often as I generally 
forget what or why to do in particular cases from one project to the 
other. Re-inventing the wheel each time as it were...

Your example looks very neat. I shall study it some more and take 
inspiration from it.

> [snip]
> 
> This, as just a simple prototype.
> Something better that takes all the information (filter, transmit, multipliers)
> would be nice, and would have sanity checks for out of range values, negative
> values, etc.
> 
> Maybe I need to go back to the scenes where I was working out the srgb math and
> use that to make a documentation infographic, and possibly an animation.
> 
> It would be way better to have a nice, fully presented thing in the distribution
> that lays out all of the whys and hows, than to have to rehash this topic ever
> few years.
> 
Not that I mind to re-ignite the discussion every few years as I seem to 
do ;-) but I fully agree with you on this.

> Than people can visually and mathematically see what the byte triplet values
> are, the in-range nonlinear srgb values are, the in-range linear rgb values, and
> how they all relate to one another.   Just do a simple animation from <0, 0, 0>
> to <255, 255, 255>, and I think that might very well cover it.
> Some examples that simultaneously show the incorrect way to convert from srgb to
> rgb would likely be helpful as well.
> 
> - BW
> 

-- 
Thomas


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