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Topic: Any way to easily change shadow color in AoI?

I have been messing with this by changing ambient color some and using lots of different lights, but I have problems like if diffuse is solid red on an object, and the light/ambient color is sort of green they cancel each other and make the shadow there black instead, just wondering if anyone knows a way in AoI 2.9.1 to do this better without tinting the entire picture.

May it be an evening star
Shines down upon you
May it be when darkness falls
Your heart will be true

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Re: Any way to easily change shadow color in AoI?

Ok, first let me make sure that I understand you correctly. You have:
    -A pure red cube.
    -A greenish ambient light.
    -One or more various other lights.

    -You are wondering why the shaded side of the cube (lit only with ambient) renders as black.

If I got it right, keep reading. If not, please explain where I went wrong.

What is happening here is that your red material cannot reflect green/blue light, so the cube appears black. You can see the same effect in real life. Take a green LED and a red apple into a dark room. The apple will appear black.

Of course, 'pure' colors are rare in real life. (a laser beam and a narrow range LED are a couple of the more common sources) So your apple will probably reflect a little green light. It is also probably a little shiny, and that has an effect.

There was a thread on this forum a while back that went into a lot more detail. The guy really pushed things to an extreme with very bright lights. It had pictures. But I can't find it right now. hmm

The short version: Don't use 'pure' colors.

Add a little green and blue to your red. (does not take much -  0.01 or less might do it. Experiment.)

Make sure there is a little red in your 'greenish' light. (again, just a little.)

Also, might try bumping your specularity up a hair - Very few objects are perfectly Matte. You might have to increase surface roughness if you do this, so that you do not get reflections where you do not want them.

Of course, there are exceptions to these suggestions. If your green was supposed to be from a laser, you would want to keep it pure, but then black shadowed areas would be expected.

Hope this helps. I'd like to hear how it turns out.

LJS

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Re: Any way to easily change shadow color in AoI?

I will keep you updated if I succeed, I knew how the light colors canceled with diffuse, what I was hoping for was something like a way to disable the diffuse part of the light (I think Blender has this but not sure), my current trend has moved a bit away from the lighting problem for now though, I am practicing modeling some "relief" type scenes, that aren't truly 3d, but have been given depth from the 3d capability of AoI, so basically I can quickly reproduce a single angle, like if I am tracing a movie poster, and take advantage of some of the lighting abilities by giving the 2d trace depth and curvature, so that it does fancy shading.

I have some pretty decent success with this method so far, am working on reproducing a movie poster in my own style, will post it in one of the stills areas when I am done big_smile

May it be an evening star
Shines down upon you
May it be when darkness falls
Your heart will be true

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Re: Any way to easily change shadow color in AoI?

Hi.

I'm bit late with my response, but did you have something of this kind in mind?

(click to enlarge)
http://www.kuukahvila.com/peteihis/AOI/howto/Colored_Shadows/Green_Shadows.jpg

The idea is to split the light source into to parts that added together make the white light (or the light of the color you wish to use). One of them emits the color of the shadows, and that color is subtracted from the color of the other one. Then the shadow colored light is tagged "shadowless" (which may sound is a bit of a paradox...). It may also be a good idea to reduce the ambient color closer to black.

The file

detective

Last edited by peteihis (September 16, 2012, 6:47 am)

...there's more to the picture than meets the eye...

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Re: Any way to easily change shadow color in AoI?

Hmm .... for the relief type of a thing you'd probably want the unlighted surfaces to have the coloured effect?

Sounds like you could play - not only with the ambien golor setting, but also with procedural textures. The View angle module maybe? And coming to think of it, also the procedural lights might have something useful to offer. I haven't done much with those, though, so can't really say.

Last edited by peteihis (September 16, 2012, 7:18 am)

...there's more to the picture than meets the eye...

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Re: Any way to easily change shadow color in AoI?

Ya petehis, that is what I am going for, my question though is, if you turn the background plane the shapes are on the anticolor of the shadow light, say, your light is green and your background plane is red, does it turn the shadows black?

If it stays green, that is exactly what I want, and wouldn't mind having that aoi file to examine big_smile

Also, I notice in the picture you put up that the object shades are still sort of black, I want the shades to be tinted as well in the region where the darkness is.

I have played around with the subtraction of lights, but I was using ambient instead, maybe the shadowless will work better.

May it be an evening star
Shines down upon you
May it be when darkness falls
Your heart will be true

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Re: Any way to easily change shadow color in AoI?

been a while since I attempted this, but I got it working the way I wanted it, your idea was perfect to have 2 lights adding to a regular one, with one being the shadow as ambient light and the other as normal point light to fulfill the rest of lighting, as you can see the shadows and darkness are basically the right color of red, the only exception being where the color cancels the light, so on the green surface it is opposite of red, which turns it black.  For the purpose of a mostly one color (likely gray or white) relief it wouldn't be a problem though.

Your original pic appears to have worked the way I wanted at least on the green cube and part of the yellow pyramid you can see a green shade on the backside from the white light also, was probably just a bit dim to show up on the other colored blocks.

In the pic below the truck is green and red with slightly darkened purple tires, and the cylinder underneath is a default white color.  With the only not tinted shadow on the green surface.

LJS had the problem from the start as well it seems.

Last edited by doomseer (January 24, 2017, 1:25 am)

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May it be an evening star
Shines down upon you
May it be when darkness falls
Your heart will be true

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