Question Changing received shadow color

I'm working on a shader and have reached a stumbling point. I'd like to be able to set the color of the shadow that an object receives. Is this possible? Any pointers?

 

hdrp or lwrp/urp? latter would be easy by writing a custom lighting function which splits attenuation into distance atten and shadow atten. then you take the shadow atten and lerp/multipy the lit result with your shadow color.

 

I'm using Lwrp/urp. I have no idea how to write that function but I'll look into it. For now, I'm setting the ambient light color in the scene, but that isn't really the effect I'm going for.

 

I was able to get all of this working. Thanks for the help. I was basically trying to create a shader that would meet the following requirements:

• Toon shading
• Casts and receives shadows with shadow colors being variable
• based color variable based on camera distance
• shadows and shading variable based on camera distance

I was able to get everything working. My last step is to add in rim lighting, also having intensity based on camera distance.

 

I'll add an answer here because this thread comes up in search queries, but there's no usable answer here.

As best I know, there really isn't a way to change the color of "cast shadows" because the color is generally "received". This means the shader coloring a model has to do the work to multiply a color value instead of just 0 (aka black).

The Custom Lighting in Shader Graph blog has a nice step-by-step solution on how to control the lighting / shadowing of a model using a Shader Graph generated shader. Once the example from the blog is working, the next step is fairly easy.

Instead of sending the dot product of the world-space normal and the direction of the light into saturate, to calculate NdotL, send the dot product result into a remap{[-1,1]=>[0,1]}, and then use the output value as the input into a gradient sampler. The gradient to be sampled should be the color of you shadow to white.

 

oh, yes. depends on what "shadows" means for you. i only thought about real time shadows

here i collect light color, intensity and distance attenuation separately from NdotL and shadow attenuation and finally take both to colorize the final pixel and blend between 2 texture sets.



more info about custom lighting and lwrp: https://medium.com/@larsbertram1/lwrp-and-custom-lighting-in-shader-graph-6a7c48008a1d

the entire toon shader is part of my Lux LWRP Essential package, currently at sales
https://assetstore.unity.com/packages/vfx/shaders/lux-lwrp-essentials-150355

 

Great write up. To address the issue at the end you cover about being forced to use emission instead of albedo, I create a custom Shader Graph Master Node and submitted it to Unity. They're in the middle of a Shader Graph re-write so they kindly rejected my submission, but you can still feel free to use it.

https://github.com/Unity-Technologies/ScriptableRenderPipeline/pull/4912

To try it...

1. Start Unity 2019.3b (beta 8 or later should work)
2. Copy the files from the pull-request into the PackageCache folder of your target project
3. Give Unity desktop focus (click on its Window) and it'll compile
4. Now create a new Shader Graph and you'll the option for `Surface Graph`

Best of luck!