Is it possible to change the shadow output? Tweet

[fivebythree]

Hi,

Wracking my head around this. I've tried specular material which gives a bit of an undesired result.

I'd like to assign an rgb value to the output shadow of a single object, but not the rest of the scene.

See the attached video as a primer to better understand what I'm after...
https://www.youtube.com/watch?v=EN_xB9Fkw9M&t=24s


Any help would be greatly appreciated.

thanks,
Dom

[funk]

You could mix 2 materials with a ray switch node in a similar way to the blender video.

Just tweak the specular material to get the look you want (I set IOR to 0, enabled fake shadows and made refraction blue)

See attached scene.

[fivebythree]

Wow, I was doing this wrong! I was using the mix texture node and not the Mix Material. Thanks for you help! It's exactly the result I was in need of.

[fivebythree]

I have a bit of a follow up to this question.

Shadows are passing through the mix material. Is it possible to prevent this? The diffuse material seemingly does this, but the specular material seems to allow the shadow from another object to pass right through. Here's an image to illustrate the issue.....

Thanks again,

Domenic

[frankmci]

I think what you are seeing is the logically correct shadow. It's like stacking filters; the blue building has already blocked the red light, so there's none left to go through the pink building. Where the shadows overlap, you'll get only what frequencies can pass through both buildings. You may need to do separate shadow passes and color them in post to make the pink building cast a pink shadow after being blocked by a blue shadow.

But don't give up yet. There are people here far cleverer than me who might have an elegant in-camera solution.

[fivebythree]

I think what you are seeing is the logically correct shadow. It's like stacking filters; the blue building has already blocked the red light, so there's none left to go through the pink building. Where the shadows overlap, you'll get only what frequencies can pass through both buildings. You may need to do separate shadow passes and color them in post to make the pink building cast a pink shadow after being blocked by a blue shadow.

But don't give up yet. There are people here far cleverer than me who might have an elegant in-camera solution.

Appreciate your tips. I figure its going to either be a really difficult set of steps or something blatantly easy. I think I'm not entirely understanding the ray-switch node. The documentation is rather limited on the standalone manual. Perhaps there's deeper documentation on C4D or Blender's manuals.

[funk]

I'm not seeing an obvious way to do what you want in a single render. I think you'd need to do this with separate passes.

Someone smarter than me may have other ideas.