POV-Ray : Newsgroups : povray.binaries.images : Revisiting Norbert Kern's Position Pattern Trick Server Time: 14 Dec 2018 10:27:26 GMT
  Revisiting Norbert Kern's Position Pattern Trick (Message 1 to 4 of 4)  
From: Thomas de Groot
Subject: Revisiting Norbert Kern's Position Pattern Trick
Date: 11 Jul 2018 11:22:03
Message: <5b45e85b@news.povray.org>
I refer to Norbert's 2012 message 
http://news.povray.org/povray.binaries.images/thread/%3C4f661a38%241%40news.povray.org%3E/

I wanted to find out by myself how to model an autumn tree/shrub, using 
the mesh2 file provided by Poseray as a basis. So, I did not use 
Norbert's trick here. And indeed, like Nobert said, the render speed 
dropped dramatically, but at least I understand texture patterning 
better. As an example I used an Xfrog shrub (Cotoneaster integerriums - 
Wild cotoneaster). The image is from my tree testing code.

For those interested, here is the code used (beware line breaks):

//start code
//=================================================================
#declare Obj_Leaf_ =
//The leaf image_map:
#declare PR_DIFFUSE = pigment {p_map2}
//Two colour variations using Poseray's pigment_multiply macro:
#declare PR_DIFFUSE1 = pigment {pigment_multiply(PR_DIFFUSE, 
pigment{color srgb ((<1.00, 1.00, 0.00>-<1,1,1>)*1.00+<1,1,1>) })}
#declare PR_DIFFUSE2 = pigment {pigment_multiply(PR_DIFFUSE, pigment 
{color srgb ((<1.00, 0.00, 0.00>-<1,1,1>)*1.00+<1,1,1>) })}
//A facultative uv-map scaling that may be set in Poseray:
#declare PatternScale = <1.25, 1.25, 1>;

//Finish decalration:
#declare F1 =
finish {
   specular  0.2
   roughness 0.001
   diffuse  0.8
   reflection {0 }
   conserve_energy
}

//First texture definition with variation 1 of the leaf image_map:
#declare T1 =
texture {
   pigment {uv_mapping PR_DIFFUSE1 scale PatternScale }
   finish {F1}
}

//Second texture definition with variation 2 of the leaf image_map:
#declare T2 =
texture {
   pigment {uv_mapping PR_DIFFUSE2 scale PatternScale }
   finish {F1}
}

//A general transparency texture definition:
#declare T3 =
texture {
   pigment {rgbft <0, 0, 0, 1, 1> }
}

//First patterned texture definition using a leaf mask image_map:
#declare T4 =
texture {/*uv_mapping*/
   pigment_pattern {uv_mapping p_map3 scale PatternScale }
   texture_map {
     [0 T3]
     [1 T1]
   }
}

//Second patterned texture definition using a leaf mask image_map:
#declare T5 =
texture {/*uv_mapping*/
   pigment_pattern {uv_mapping p_map3 scale PatternScale }
   texture_map {
     [0 T3]
     [1 T2]
   }
}

//Final material bringing it all together in a spherical texture pattern:
material {
   texture {
     spherical
     texture_map {
       [0.10 T5]
       [0.90 T4]
     }
     translate 1*y  //the spherical pattern is at the origin; you need 
to position it
     warp {turbulence 0.3} //some warp makes the pattern more natural 
looking
   }
}

//=================================================================
//end code

-- 
Thomas


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Attachments:
Download 'povtree_test.jpg' (256 KB)

Preview of image 'povtree_test.jpg'
povtree_test.jpg


 

From: Bald Eagle
Subject: Re: Revisiting Norbert Kern's Position Pattern Trick
Date: 12 Jul 2018 14:15:01
Message: <web.5b47625d92c31acac437ac910@news.povray.org>
Nice!

Thanks for posting this, Thomas.   I was pondering how to go about this last
autumn, and perhaps if I can ever get ngPlant up and running, and have enough
time, I can actually get around to making some outdoor scenes.

Can you provide a little bit of background / explanation about the first few
lines and the PoseRay macros...   ?

Thanks


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From: Thomas de Groot
Subject: Re: Revisiting Norbert Kern's Position Pattern Trick
Date: 13 Jul 2018 06:49:25
Message: <5b484b75$1@news.povray.org>
On 12-7-2018 16:14, Bald Eagle wrote:
> Nice!
> 
> Thanks for posting this, Thomas.   I was pondering how to go about this last
> autumn, and perhaps if I can ever get ngPlant up and running, and have enough
> time, I can actually get around to making some outdoor scenes.
> 
> Can you provide a little bit of background / explanation about the first few
> lines and the PoseRay macros...   ?
> 
> Thanks
> 

No problem.

1) The Poseray macros are those which are included standard in any 
material include file when exporting from Poseray to POV-Ray. It is fun 
to play with them and I recommend to do it. The only macro 
'automatically' and widely used by Poseray is the pigment_multiply() 
one. The way in which this is done changed somewhat with the Poseray 
version. Originally, it was used in the form, e.g.:

#declare PR_DIFFUSE = pigment {p_map2}
#declare PR_DIFFUSE = pigment {pigment_multiply(PR_DIFFUSE, 
pigment{MyPigment})}

Where MyPigment was defined under the Poseray Materials tab by setting 
the Color and Filtering values for the used Pigment (aka image_map).

In the latest Poseray version, the exported use of the macro is as shown 
in my code:

#declare PR_DIFFUSE = pigment {p_map2}
#declare PR_DIFFUSE = pigment {pigment_multiply(PR_DIFFUSE, pigment 
{color srgb ((<MyColor>-<1,1,1>)*MyFilter+<1,1,1>) })}

Where MyColor and MyFilter are respectively the Color and Filtering 
values set in Poseray and mentioned above. I suppose FlyerX has good 
reasons for this change of code ;-)


2) Now you can understand what I did. I declared two different diffuses 
with a simple yellow and red colour code respectively. I declared 
separately a scale vector for the uv map, which I had set previously 
under the Poseray Materials tab, under the Transform... button.

For this example, I kept as much as possible the writing style of 
Poseray. You may adapt that to your own preferences of course, which I 
do all the time.

-- 
Thomas


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From: Thomas de Groot
Subject: Re: Revisiting Norbert Kern's Position Pattern Trick
Date: 13 Jul 2018 06:59:18
Message: <5b484dc6$1@news.povray.org>
On 11-7-2018 13:21, Thomas de Groot wrote:
> I refer to Norbert's 2012 message 
>
http://news.povray.org/povray.binaries.images/thread/%3C4f661a38%241%40news.povray.org%3E/

> 

My next goal of course is to work my way through Norbert's instructions 
and compare. Originally, I had thought I could get away with simply 
tweaking the mesh2{} files and bypass the need for intermediate mesh{} 
files, but I begin slowly to understand that that is not as easy as I 
dreamed... Mesh2{} files are devilish.

All this with the ultimate goal of applying the trick to my Crossing 
Border scene.

-- 
Thomas


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