Wow!
Game (height)map designers may find this very useful.
I like this!
Neat!!!
-
Is the light source’s position fixed?
-
There’s some indication of back-reflection; is that it, or do you specify some sort of ‘fill’ light?
Again, Neat! Neat!
No, light position (in 3D) is a setting of the filter, so you can place it anywhere.
No, I’ve just implemented the formulas from Phong reflection model - Wikipedia and got that rendering. I haven’t checked if this was correct as the results already looked cool to me 
Well, I’d assert “looks cool” is a fundamental test of ‘correctness’ in imaging!
Neat!
(I am the Knight who says ‘Neat!’ And so I say, ‘Illuminate a Shrubbery!!!’ )
Makings of a good filter. First impressions:
– Illumination currently makes it look like it is over- or unevenly inflated. Something between this and the render in Gmic for animation - #13 by David_Tschumperle might be an improvement.
– The sharp edges and their illumination break the illusion of 3d-ness.
Source: Wikipedia
Source: My Little Day
When this is done, could we have I chocolate filter? 
Source: Wikipedia
(This might be a joke. Secretly, I am hoping for the illumination of not just empty shapes but ones with relief as well, like the ridges on the chocolate piece.)
http://dcgi.felk.cvut.cz/home/sykorad/ink-and-ray.html
It would like me that it was multilayer. Putting each inflammation in different “Z” levels
Looks impressive David; sort of like Bevel Reflect Logo. Maybe give option to add different types of textures to would be cool. 
So, here it is !
A first version of the filter Light & Shadows / Illuminate 2d shape has been published today, and should be available for users of the G’MIC plug-in for GIMP and Krita (requires version 2.2.2+).
Here is a video that shows what it can do.
https://www.youtube.com/watch?v=AUVTbrdGznw
Right now, I admit I’m quite enthusiastic by this filter, as it really allows shading complex shapes with a few clicks.
Remind also that this is a first version, so subject to changes.
Please let me know what you think about it !
Some before/after comparisons :
4 Likes
I love this! <3
The Effect could separate by layers and attain something like this:
Just select Output modes -> New layers and you will get the illumination layer alone, blended with your original image.
Then you can re-work on this illumination layer to create various effects or correct light locally if you want.
1 Like
I what thought was in slight variations for each level and something similar to colorize [interactive] for the levels.
Not planed like this sorry
I will have to automate it in a script 
2 Likes
That’s interesting.
Have you used the exact same parameters of the filter for all colors ?
yes. But no it apply it to him to line (black)
You can get the same effect by playing with blending modes and opacity…
I like mine better though.