Hi,


I've tried to reproduce the lighting model used at Wolfram.
I used this example : "Phyllotaxis Spiral Pattern on a Sphere"
<https://demonstrations.wolfram.com/PhyllotaxisSpiralPatternOnASphere/>

I can't do any better than the attached image.

There are a few explanations here :
<http://reference.wolframcloud.com/language/tutorial/TheStructureOfGraphicsAndSound.html#20392>




Maybe some ideas ?

-- 
Kurtz le pirate
Compagnie de la Banquise

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Attachments:
Download 'psp01.jpg' (54 KB)

Preview of image 'psp01.jpg'

kurtz le pirate <kur### [at] gmailcom> wrote:

> I've tried to reproduce the lighting model used at Wolfram.

> Maybe some ideas ?


I gave it a go, after reading a few threads that seemed to quote what the
lighting layout is, but all I got was something a lot worse that you.

Maybe someone has a lighting demo online, or you could post to a mathematica
forum and have them make you a few test renders to analyze.

- BW

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On 21.01.2024 19:20, kurtz le pirate wrote:

> Maybe some ideas ?

Shadowless? Maybe trying some negative light?

Ilyich

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On 22/01/2024 15:51, Ilya Razmanov wrote:

> 
> Shadowless? 
already used in my sample


> 
> Maybe trying some negative light?

hum... definitely not



-- 
Kurtz le pirate
Compagnie de la Banquise

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On 22/01/2024 14:29, Bald Eagle wrote:
> 
> Maybe someone has a lighting demo online, or you could post to a mathematica
> forum and have them make you a few test renders to analyze.

I've explored (not everything, of course)
<https://mathematica.stackexchange.com/> and
<https://community.wolfram.com/> and I found nothing.


Only a nut like me would ask that kind of question.





-- 
Kurtz le pirate
Compagnie de la Banquise

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https://mathematica.stackexchange.com/questions/119804/what-is-the-default-lighting-in-3d-graphics

https://mathematica.stackexchange.com/questions/27616/what-is-the-default-colorfunction-for-3d-plots

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kurtz le pirate <kur### [at] gmailcom> wrote:
> Hi,
>
>
> I've tried to reproduce the lighting model used at Wolfram.
> [...]
>
> There are a few explanations here :
>
<http://reference.wolframcloud.com/language/tutorial/TheStructureOfGraphicsAndSound.html#20392>
>
> Maybe some ideas ?
>
> --
> Kurtz le pirate
> Compagnie de la Banquise

Hi Kurtz. I tried to replicate the example on the reference page. (Their
explanation was confusing, but I think I got the gist of it.) Here's my attempt:

// +fn +f +a0.03 +am1 +r3 +w640 +h480

#version 3.7;

global_settings{assumed_gamma 1.0}

background{rgb 1}

camera{
 right x*1.333 up y
 location <5, 7, -9>
 look_at 0
 angle 35
}

#macro Light(Pos, RGB)
 light_source{
  Pos, rgb RGB
  parallel
  point_at 0
  shadowless
 }
#end

union{
 #local Boost = 0.3;
 Light(<0, 1, 0>, x+Boost)
 Light(<1, 1, 0>, y+Boost)
 Light(<1, 0, 0>, z+Boost)
 rotate <0, 10, 10>
}

union{
 sphere{<-1, 0, -1>, 1}
 sphere{<1, 0, -1>, 1}
 sphere{<-1, 0, 1>, 1}
 sphere{<1, 0, 1>, 1}

 pigment{rgb 1}
 finish{brilliance 1.5}
}

#include "shapes.inc"

Wire_Box_Union(<-2, -1, -2>, <2, 1, 2>, .004)

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Attachments:
Download 'wolframlightingtest.jpg' (21 KB)

Preview of image 'wolframlightingtest.jpg'

"Samuel B." <stb### [at] hotmailcom> wrote:
> my attempt

The colors and gamma are all wrong, partly due to the 'Boost' value. You can
change assumed_gamma to 1.3, which helps, but still isn't quite the same.

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On 23/01/2024 18:55, Samuel B. wrote:

> 
> Hi Kurtz. I tried to replicate the example on the reference page. (Their
> explanation was confusing, but I think I got the gist of it.) Here's my attempt:
> 
> [snip]

Hi Samuel,

Good job too.
I made nearly the same code as you ;)
And still not the same look.

With a link given by BW, i found more infos about lightning :
Graphics3D [
 Sphere[],
 Lighting -> {
  {"Ambient", RGBColor [0.40, 0.20, 0.20] },
  {"Directional",RGBColor [0.00, 0.18, 0.50],ImageScaled [{2, 0, 2} ]},
  {"Directional",RGBColor [0.18, 0.50, 0.18],ImageScaled [{2, 2, 3} ]},
  {"Directional",RGBColor [0.50, 0.18, 0.00],ImageScaled [{0, 2, 2} ]},
  {"Directional",RGBColor [0.00, 0.00, 0.18],ImageScaled [{0, 0, 2} ]}
  }
]
I didn't really understand the ImageScaled[] syntax, but even with these
parameters, the rendering is different.




-- 
Kurtz le pirate
Compagnie de la Banquise

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kurtz le pirate <kur### [at] gmailcom> wrote:

> I didn't really understand the ImageScaled[] syntax, but even with these
> parameters, the rendering is different.

As I understand it, ImageScaled is used as a multiplier, and is a value based on
the screen coordinates of the image.

So, if you had a sphere at <4, 0, 0> and it was right at the edge of the screen,
the x coordinate of ImageScaled would be 4.   Same with y.
So it seems to be like <image_width, image_height> only in POV-units perspective
screen space.

https://reference.wolfram.com/language/ref/ImageScaled.html

- BW

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