no G'MIC (Patterns/Rays), only with the GIMP tool


2 Layers of different colors, I chose red and yellow for this exercise.
Then on the top layer (yellow) "Filters >> Distorts >> Kaleidoscope"
Make sure to reset the filter, and use Mirrors for the number of yellow beams, and put the "Mirror rotation" (the first slider) to 90 degrees.

Then slide down the cursor slowly
Done!

Below is for the curious and motivated....

A bit of math...
"Mirror rotation" is up to 180 degrees, thus to see appearing the start of the "fan" you do need to be at 90 (degrees), this will be the "maxima"
In the "Mirrors" slider (the number of mirrors) by default it's 6, this number will give you the "minima" angle
So all starting at 180 degrees (let's just take the numbers now without the 0/zero))
For 6 mirrors the minima will be:
18/6=3 => 9-3=6 = 60
Thus 90 degrees minus 60 degrees = 30 degrees >> the minima will be 90 - 30 = 60, you will see the "fans" spanning from 60 to 90 on the "Mirror rotation" slider,

Why I speak about that? because if you want the 2 colors having exactly the same span => 30/2 = 15 > +60 = 75 > set the slider at 75


another example:
12 mirrors
18/12= 1.5 =(put back the 0/zero =15) 90-15= 75 so between 75 and 90 you will be able to see the "fans" spanning and to have the exact spread of red and yellow 15/2= 7.5 >> 90 -7.5= 82.5 set the top slider at 82.5

18 branches... 18/18=1 the spread is 10 thus 80 to 90, middle is 85 for equal spread
20 branches...18/20= 0.9 the spread is 9 thus 81 to 90, equal spread will be 81+4.5=85.5

I see the numbers in my head, I tried hard to explain how I see them, but I agree it' might not make any sense for some
You can just do it visually

Also "Filters > Render > Line nova"

Indeed, long time ago I did tried then forget it, and today because you speak about it, I told myself "Oh yes that was it" thus I did try it again

Now I recall why I did used G'MIC
No visual reference when moving a cursor. Cannot go below 40 blades,
"Sharpness (degrees)" too confusing, never recalled what it does, now that I "understand" it's about more on one color than other, but still why 2.5 out of 10 make it equal?
On the other hand fans' edges are smoother with it,

For those who want to try it, start with this settings then push 1 slider at a time to see what it does (Ctrl+Z is your friend)

Two surprises in one post:
old script-fu line-nova.scm is a tool and G'MIC is not?
Necessity of own installation precludes the TOOL name?
These are only developers choices - I have mine.
I replaced script line-nova with this one (though old too, but with many more options).

I knew this and made a filter of it. Also the zz crap is gone thanks to MareroQ's discovery.

I totally agree with Rich when he says we should learn to utilize what GIMP can offer in creating certain renders instead of relying on scripts, so I am happy to see others dropping those ideal ways to accomplish things. On the same token, it is hopeful that the mindset isn't about ridding innovation because script writers/coders/hackers have provided us with tools to speed up our process, and that isn't a bad thing, since all a script or plugin is doing is putting the steps into sequence in one get go. Just don't get lazy and rely solely on them. We old-timers (we all know who we are) won't be here forever and preparing the noobs to step in and take over is pretty much the goal.

@MareroQ That was not my meaning ,
Huge G'MIC fan here , also I never said it, but the few scripts I have from you are absolute fantastic tools (thanks a lot) , and this goes also for @Ofnuts fabulous tools and others like @Skinnyhouse, @dinasset, etc... (I can't put all the names), thank you so much guys

@contrast_ Let's face it, this "tuto" is because of you! >> viewtopic.php?f=9&t=19948#p273837
I did tried your GEGL script, and in your post you spoke about "Kaleidoscope", I very rarely use this tool, thus I needed to understand more, thank you Beaver

@mahvin I completely agree with Rich as well

A little extra if you followed this "tuto" above, push (near the end) the "Trim X" slider after you see the 2 colors beams before clicking OK