Jim Charter <jrc### [at] msncom> wrote:

> The code I showed you was meant as more of a direction than a solution.
>
> For instance the pigment yellow and magenta pigment was included only to
> show the influence of the added blob components.  A shallower ridge can
> be gotten by tweaking down the threshold value ( get it low, maybe .03
> or so ) while increasing the radius of the ridge blobs ( maybe .14 )
> You migh also notice that I also locate the blobs just under the surface
> of the ball.
>
> Also in the original thread you quoted, H E Day posted a suggestion for
> how to "feather" the edges ( which was the original question on the
> thread.)  His suggestin was to replace each blob component with several
> in the same place each one trading off radius v strength
>
> So
>
> instead of something like:
>
> Radius=.14
> Strength=1
> blob { threshold .03
>  sphere { 0, 1, 1 }
>  STARTLOOP
>   sphere ( Location, Radius, Strenght )
>
>  ENDLOOP
> }
>
> do something like:
>
> Radius1=.10
> Strenght1=1.2
> Radius2=.12
> Strength2=1.1
> Radius3=.14
> Strenght3=1.0
>
> blob { threshold .03
>  sphere { 0, 1, 1 }
>  STARTLOOP
>   sphere { Location, Radius1, Strength1 }
>   sphere { Location, Radius2, Strength2 }
>   sphere { Location, Radius3, Strength3 }
>  ENDLOOP
> }
>
> I think you could try and tweak these factors before we attack the
> threading issue.
>
> I am not sure how radically you would need to vary the Radius and
> Strenght over the three "copies" in order to get the effect H Day
> describes.  I have never tried the technique myself.  But H E Day was a
> blob master.  Perhaps try some controlled experiments to assure yourself
> of how the technique works before working directly on the ball model.
>
> -Jim

I'll try to go in the direction you have indicated.  It will probably be a
few days before I post back what I have put together. It may have to wait
until the weekend.  Thanks for your sharing of knowledge.
-Wayne

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wayne461 wrote:
> Jim Charter <jrc### [at] msncom> wrote:
> 
> 
>>The code I showed you was meant as more of a direction than a solution.
>>
>>For instance the pigment yellow and magenta pigment was included only to
>>show the influence of the added blob components.  A shallower ridge can
>>be gotten by tweaking down the threshold value ( get it low, maybe .03
>>or so ) while increasing the radius of the ridge blobs ( maybe .14 )
>>You migh also notice that I also locate the blobs just under the surface
>>of the ball.
>>
>>Also in the original thread you quoted, H E Day posted a suggestion for
>>how to "feather" the edges ( which was the original question on the
>>thread.)  His suggestin was to replace each blob component with several
>>in the same place each one trading off radius v strength
>>
>>So
>>
>>instead of something like:
>>
>>Radius=.14
>>Strength=1
>>blob { threshold .03
>> sphere { 0, 1, 1 }
>> STARTLOOP
>>  sphere ( Location, Radius, Strenght )
>>
>> ENDLOOP
>>}
>>
>>do something like:
>>
>>Radius1=.10
>>Strenght1=1.2
>>Radius2=.12
>>Strength2=1.1
>>Radius3=.14
>>Strenght3=1.0
>>
>>blob { threshold .03
>> sphere { 0, 1, 1 }
>> STARTLOOP
>>  sphere { Location, Radius1, Strength1 }
>>  sphere { Location, Radius2, Strength2 }
>>  sphere { Location, Radius3, Strength3 }
>> ENDLOOP
>>}
>>
>>I think you could try and tweak these factors before we attack the
>>threading issue.
>>
>>I am not sure how radically you would need to vary the Radius and
>>Strenght over the three "copies" in order to get the effect H Day
>>describes.  I have never tried the technique myself.  But H E Day was a
>>blob master.  Perhaps try some controlled experiments to assure yourself
>>of how the technique works before working directly on the ball model.
>>
>>-Jim
> 
> 
> I'll try to go in the direction you have indicated.  It will probably be a
> few days before I post back what I have put together. It may have to wait
> until the weekend.  Thanks for your sharing of knowledge.
> -Wayne
> 
You're welcome.  I am not sure how much you understand about the 
concepts behind these techniques or have knowledge of POV's SDL, but if 
you don't you should take this opportunity to research these things. 
This is a great project for refining your abilities with vectors, 
transforms, and splines.  Right now we are operating pretty much at the 
limits of my understanding.

Again I want to emphasize that the code* I showed you is quite 
abbreviated.  Not only can the parameters be tweaked but the code could 
and should be further refined.

For instance, right now the "Seg" vector is dependent on the size of the 
"step" we use to "walk" along the spline .  This, of course is 
controlled by the "Grain" value.  Seg should be uncoupled from Grain. 
Worse, the length of "Cross" is related to the length of "Seg".  Cross 
should be "normalized" so it is independent of Seg and can be scaled in 
POV units.

Also, I would suggest incorporating the rand() function to "jitter" the 
placement, even the size, of the blobs forming the ridge so that it
will appear less regular.

*some on the groups here wince when we refer to SDL as "code".  To many 
hardcore programmers it is "script".  Otoh, SDL is also held to be a 
"turing-complete" programming language, so go figure.

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Jim Charter wrote:
> *some on the groups here wince when we refer to SDL as "code".  To many 
> hardcore programmers it is "script".  Otoh, SDL is also held to be a 
> "turing-complete" programming language, so go figure.

Well, my viewpoint is as a non-professional, amateur/hobbyist 
programmer, mostly with C.  I see the difference between code and a 
script as this:  code is compiled into a different form (program code 
becomes executable machine-language code), while a script is a set of 
instructions that are directly run to perform some set of operations. 
Rendering SDL is in effect compiling it, where it becomes an image file. 
  It is not run as a set of instructions, it is a set of descriptions, 
therefore it is code and not a script.

Of course, realistically, who cares whether the SDL is called code or 
script, that's completely irrelevant.  Just use it and enjoy.    :-)

Just one (lay-)person's opinion...

      -=- Larry -=-

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Jim Charter <jrc### [at] msncom> wrote:

> >
> The math on the page Jellby quoted might be used to make a more accurate
> spline. Not urgent at the moment. Mine is not very accurate. But in my
> opinion using a spline gives the ability to work within sdl without
> knowing sophisticated math.
>

>
> -Jim


I haven't gotten back to this recently but the other day I did stumble upon
another site witht he formula for the baseball seam.
http://astronomy.swin.edu.au/~pbourke/curves/baseball/index.html

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