color wheel in gimp method?

[marigolden]

Any idea on how to make a color wheel in gimp?
Just a simple pie visual, except instead of for the purpose of percentages it's just to show the rainbow +3 other colors (white, brown, and black) so 9 colors in all

[denzjos]

1/ draw a circle
2/ on gimp menu : Select / To Path
3/ draw a straight vertical line  (lenght diameter circle)
4/ select the line (Fuzzy Select tool)
5/ on gimp menu : Edit / copy
6/ on gimp menu : Select / None
7/ on gimp menu : Edit / Brush strokes on path (value 9 in your case)
8/ clean up the rays
9/ color the sections ( fuzzy select section/ fill section with color 'Bucket Fill Tool') 

PS : Brush strokes on path is a plugin from Ofnuts

[marigolden]

(03-12-2020, 04:38 PM)denzjos Wrote: 1/ draw a circle
2/ on gimp menu : Select / To Path
3/ draw a straight vertical line  (lenght diameter circle)
4/ select the line (Fuzzy Select tool)
5/ on gimp menu : Edit / copy
6/ on gimp menu : Select / None
7/ on gimp menu : Edit / Brush strokes on path (value 9 in your case)
8/ clean up the rays
9/ color the sections ( fuzzy select section/ fill section with color 'Bucket Fill Tool') 

PS : Brush strokes on path is a plugin from Ofnuts

Thank you. What I've ended up doing is just taking a preexisting color wheel, which happens to have 12 pieces, using the path tool to cut out 1.33 portions and am recoloring each to make 9 pieces.

[Krikor]

(03-12-2020, 04:38 PM)denzjos Wrote: 1/ draw a circle
2/ on gimp menu : Select / To Path
3/ draw a straight vertical line  (lenght diameter circle)
4/ select the line (Fuzzy Select tool)
5/ on gimp menu : Edit / copy
6/ on gimp menu : Select / None
7/ on gimp menu : Edit / Brush strokes on path (value 9 in your case)
8/ clean up the rays
9/ color the sections ( fuzzy select section/ fill section with color 'Bucket Fill Tool')

PS : Brush strokes on path is a plugin from Ofnuts

Hi denzjos, I tried to follow the steps but in the end, I didn't get 9 equidistant sections.
The vertical green line in the center served as the basis for the rays (step 03).

Note that not all rays converge towards the center.
   
How do you make the result really a uniform division of the 9 rays around the circle?
Thx.

[rich2005]

Start off with a square image and the required equal sized stripes.

Apply Filters -> Distorts -> Polar Coordinates.

   

edit: marigolden - rainbow, (visible spectrum) = red, orange, yellow, green, blue, indigo and violet

[Krikor]

I used the script that appears in the image menu (I don't know the name of this script) and the divisions were exact, in nine equal parts, then it was just coloring.
https://imgur.com/a/5li05kz

Edit:
Rich2005, I did it using this method that you showed (polar coordinates) and it was much easier and faster! :-)

[denzjos]

(03-12-2020, 08:04 PM)Krikor Wrote:

(03-12-2020, 04:38 PM)denzjos Wrote: 1/ draw a circle
2/ on gimp menu : Select / To Path
3/ draw a straight vertical line  (lenght diameter circle)
4/ select the line (Fuzzy Select tool)
5/ on gimp menu : Edit / copy
6/ on gimp menu : Select / None
7/ on gimp menu : Edit / Brush strokes on path (value 9 in your case)
8/ clean up the rays
9/ color the sections ( fuzzy select section/ fill section with color 'Bucket Fill Tool')

PS : Brush strokes on path is a plugin from Ofnuts

Hi denzjos, I tried to follow the steps but in the end, I didn't get 9 equidistant sections.
The vertical green line in the center served as the basis for the rays (step 03).

Note that not all rays converge towards the center.

How do you make the result really a uniform division of the 9 rays around the circle?
Thx.

[quote pid='17209' dateline='1584043492']
Sorry about that, it seems that the angle from the first line is not known in the Ofnuts plugin.
I don't know if Ofnuts has an explanation about that?
There exist another script that do the job (I've seen there is a much better solution shown by rich2005 that is preferable)  
but I just want to mention the plugin here :
 
https://gimplearn.net/viewtopic.php/Mura...t?f=4&t=16

- gimp menu : File / New (equal layer dimensions - square)
- make a cross with 2 guides in the middle of the layer
- draw a circle with the centerpoint in the middle
- gimp menu : Edit / Stroke selection
- gimp menu : Select / None
- make a new transparent layer
- draw vertical line from the center of the circle to the circle circumference on the new layer
- gimp menu : Script-Fu / Mura Meister Copies..
- fill the values in from the centerpoints and the number of copies (= sections)
- the different sections are made  
[/quote]

[rich2005]

...or... A (really) old script shape-path.scm
It is in the zip here, with another script https://www.gimp-forum.net/attachment.php?aid=2538

I use it just because it is script-fu and I can load it quickly without closing Gimp

Using the star option, with a zero center radius produces spokes. All in one screenshot: 

   

[Ottia Tuota]

Another way to draw the figure is my new (and very unfinished) plugin Simple parametric curve.

I show first the result:

   

The plugin makes this as two vectors objects as follows:

   

These could then be stroked. Since you already got other solutions, I don't go to details. I just say that the plugin is obtained here (see the first post):

https://www.gimp-forum.net/Thread-Parametric-curves

and to draw the figure you tell the plugin to take inputs from a file. That file must be created before-hand. I draw the above figure with a file with the following contents:

Code:

# Pie. Input file for the plugin Simple parametric curve.

N = 9

center = [500,500]
scale = 300

curve_name = 'Pie'

def function(t):
   return [cos(t),sin(t)]

interval = [0,2*pi]

mark_linesegments = [
                    [[0,0], function(i*2*pi/N)] for i in range(N)
                   ]

[Ofnuts]

(03-14-2020, 02:38 PM)denzjos Wrote: Sorry about that, it seems that the angle from the first line is not known in the Ofnuts plugin.
I don't know if Ofnuts has an explanation about that?

About what?