Re: Re: Randomized gradient

buralex@xxxxxxxxx · Wed, 21 May 2008 17:53:54 -0400

  "Ken" <kenba_nistu@xxxxxxxxx> said on May 20, 2008 22:01 -0400 (in part):
>> I'd guess to make a Filter -> Render -> Clouds -> Plasma, and then
>>     
> take a 
>   
>> > 1-pixel-wide column from it, then scale it as wide as you need the
>>     
> gradient to 
>   
>> > be... then apply it wherever you need the gradient.
>> > 
>> > Example: http://supersilly.com/~greg/images/random_gradient.jpg
>> > 
>> > No idea about alpha, though...
>> > 
>> > --GAck
>> >
>>     
>
> This isn't what I mean. How would the gradient tool use this. I want
> random gradients for the gradient tool. I guess I wasn't as clear
> before as I thought I was. It sure seems like there should be a plugin
> or script-fu thingy out there somewhere that will do this.
I followed Greg's suggestion too: use Filter -> Render -> Clouds -> 
Plasma then take a 1-pixel strip and resize till it fills the entire 
image. After looking at how the Gimp-Gradients tool works I realized 
that I couldn't see any way to take this strip and turn it into a 
gradient (so it could be applied to arbitrary images) with support for 
the options that gradient tools supports - select a Mode, Opacity, Shape 
and Repeat, Dithering-ON/OFF, Adaptive Supersampling-ON/OFF.

The first two (Mode+Opacity) can be handled by creating a layer 
containing the resized 1=pixel strip but I can't see any way to handle 
the remaining ones?

Looking at a GGR file it appears to be just a text file with a variable 
number of lines of info.
eg. here are the contents of Abstract_1.ggr
It contains 13 columns of info per entry and appears to be suitable for 
manipulation in a spreadsheet etc. if I knew what the contents of each 
column are supposed to represent.

    * GIMP Gradient
    * Name: Abstract 1
    * 6
    * 0.000000 0.286311 0.572621 0.269543 0.259267 1.000000 1.000000
      0.215635 0.407414 0.984953 1.000000 0 0
    * 0.572621 0.657763 0.716194 0.215635 0.407414 0.984953 1.000000
      0.040368 0.833333 0.619375 1.000000 0 0
    * 0.716194 0.734558 0.749583 0.040368 0.833333 0.619375 1.000000
      0.680490 0.355264 0.977430 1.000000 0 0
    * 0.749583 0.784641 0.824708 0.680490 0.355264 0.977430 1.000000
      0.553909 0.351853 0.977430 1.000000 0 0
    * 0.824708 0.853088 0.876461 0.553909 0.351853 0.977430 1.000000
      1.000000 0.000000 1.000000 1.000000 0 0
    * 0.876461 0.943172 1.000000 1.000000 0.000000 1.000000 1.000000
      1.000000 1.000000 0.000000 1.000000 0 0

Can any one point to documentation somewhere?
Later ... Goggle is my friend <GRIN> searching for: gimp+ggr+format 
turns up (as #1 hit of 21,300) this blog entry: 
http://raikardesigns.blogspot.com/ which has a link to this explanation: 
http://rockraikar.googlepages.com/gimpGGRformat.txt :

    * GIMP Gradient
    * Name: My Grad
    * 2
    * 0.000000 0.250000 0.500000 1.000000 0.000000 0.000000 1.000000
      0.000000 1.000000 0.000000 1.000000 3 0 0 0
    * 0.500000 0.750000 1.000000 0.000000 1.000000 0.000000 1.000000
      0.000000 0.000000 1.000000 1.000000 4 0 0 0
    * ------------------------------------------------------
    * First line says it is a gimp gradient file.
    * Second line gives your Gradient a suitable name.
    * Third line tells the number of segments in the gradient.
    * Each line following defines the property of each segment in
      following order.
    *  1. [position of left stoppoint]
    *  2. [pos. of middle point]
    *  3. [pos. of right stoppoint]
    *  4. [R for left stoppoint]
    *  5. [G for left stoppoint]
    *  6. [B for left stoppoint]
    *  7. [R for right stoppoint]
    *  8. [G for right stoppoint]
    *  9. [B for right stoppoint]
    * 10. [Blending function constant]
    * 11. [Blending function  constant]
    * 12. [Blending function constant]
    * 13. [Blending function constant]

So it looks to create a "Random" gradient all you have to do is choose 
for each line values for 1,2,3 so that line-1-column-1 is 0.0, 
line-last-column-3 is 1.0 with the values columns 1,2,3 increasing in 
each line.

Then choose random values for colors in columns 4-9 and blending 
function columns 10-13.
For a complicated one (46 lines) look at "Flare Glow Angular 1"
Comparing data shown in text editor with values shown in the Gimp 
Gradient editor it appears to me that the names for columns 7-9 above 
are incorrect (s/b HSV values(?)). Two of the "Blending function 
constants" are probably Luminance and Opacity. That leaves the two 
integers (12-13) unexplained. Most GGR files have values 0,0 though I 
spotted some with small integer values between 1 and 5.

Ken - does that give you enough to make a start? Please post back with 
any results etc. (I haven't tried to create any yet myself but will 
attempt it "real soon now"). If I knew how to use script-fu it also 
sounds like a "natural" for it.

(Will be Reposting to Flickr-Gimp Users group.)

Regards ... Alec -- buralex-gmail
-- 

[Non-text portions of this message have been removed]

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