Howto: wrong lighting :)

Why don't you just scale/remap the dot to whatever you want? so right now it's 1 to -1, just remap it to 1 to 0 or whatever you want. You could also look at doing a 1D texture look up to take the technique further.

What your after looks alot like the lighting model (they call it 'half-lambert') used in the Source engine (http://www.ati.com/developer/siggraph06/Mitchell-ShadingInValvesSourceEngine.pdf).

So instead of using:
NdotL
You could use:
((NdotL*0.5)+0.5)^2

Quote:

Original post by Grey_ Why don't you just scale/remap the dot to whatever you want? so right now it's 1 to -1, just remap it to 1 to 0 or whatever you want. You could also look at doing a 1D texture look up to take the technique further.

QFT. If you do a little scale/bias to bring the dot product result into the range 1 to -0.5 or whatever you want, that'll do exactly what you need.

Thank you.

It was the first thing I tried. But it wouldn't work for *me*. The reason it didn't worked: I forgot I always clamped the NdotL values (to [1.0...0.0]) [embarrass]

Quote:

What your after looks alot like the lighting model (they call it 'half-lambert') used in the Source engine (http://www.ati.com/developer/siggraph06/Mitchell-ShadingInValvesSourceEngine.pdf). So instead of using: NdotL You could use: ((NdotL*0.5)+0.5)^2

Very interesting and looks indeed quite nice! Thanks

I am wondering what is the point of such lighting. it doent seem like it can look natural.. is it used for some special effect?

It's a cheap way to fake a certain amount of subsurface scattering. On a human face for example a light shining from behind will scatter through the translucent layers of the skin and off fine hairs on the skin which will give a bit of a rim lighting type effect. Pushing the light a bit around the 'correct' cut off point for opaque lambertian diffuse lighting captures some of the visual look of the complex light transport that's going on for a translucent object. For skin shaders it's common to also tint the light that bleeds around the edges slightly red to approximate the effect of scattered light passing through blood vessels.

[edit]Here's an example of backlighting in a real photo, notice how light bleeds around the edges of the face:

Quote:

Original post by mattnewport It's a cheap way to fake a certain amount of subsurface scattering

And this I had in mind [smile]

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Original post by quasty Does anybody have an idea on how to do this?

NdotL*0.75+0.25 would give you the requested result, but to simulate subsurfacescattering it would be better to use the viewdirection instead of the lightdir, something like;

float SSS=pow(1.f-dot(N,ViewDir),8);

http://download.nvidia.com/developer/presentations/2004/Iron_Developer/English_CinematicEffectsII_Sept04.pdf#search=%22wrap%20lighting%20nvidia%22

sometimes refered to as wrap lighting, its the basis for main skin shaders
used in current games

Quote:

Here's an example of backlighting in a real photo, notice how light bleeds around the edges of the face:

this is true, so im being a prick :)
but here im sure its also due to the hair on the face / jumper (like the hair on the head but obviously much shorter)

Quote:

Original post by zedzeek this is true, so im being a prick :) but here im sure its also due to the hair on the face / jumper (like the hair on the head but obviously much shorter)

Which is why I said:

Quote:

On a human face for example a light shining from behind will scatter through the translucent layers of the skin and off fine hairs on the skin

[grin]

whoops didnt see that