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Material: control light on a object without Emissive

alt textHello,

I want to be able to control the light on a object, with the dot of a Light Direction and the vertex normal. But i can't find a way to overwrite the shadows on the model without using Emission.

I don't want to use Emission as i want shadows from other objects to land on the model.

Hope someone can help.

Best Regards Mads

Product Version: UE 4.10
lightmat.png (132.0 kB)
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asked Nov 27 '15 at 12:26 PM in Rendering

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avatar image AndrewHurley Nov 30 '15 at 08:57 PM

Hey Slasmir,

Could you provide me with a bit more context, as I am a little confused as to what you are using the emmissive input instead of the Base Color, given the control you are requesting?

In other words, what are you exactly trying to do with this material in your scene. You gave me a brief explanation, but I need a bit more to go off in order to assist you effectively.


Andrew H.

avatar image Slasmir Dec 02 '15 at 09:05 AM


Thanks for your answer.

I want to be able to have full control over the shadow and light sides of the material, if I use Base Color, the shadow side will be effected by the standard calculated light.

So all in all, I want to have the global calculations of shadows falling on the object (from other objects), but I want to control the local calculations in the vertex part of the shader where unreal uses "surface" calculations

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1 answer: sort voted first

In that case, you want to change your to material's Shading Model to 'Unlit' and the Blend Mode to 'Translucent' which will get you started in the right direction.

I believe a good example of this set up you are going for can be found within a particle system, like the impact of a bullet hitting a surface and creating the smoke effect. Below is an example of this material set up:

alt text

Hope this helps!

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answered Dec 02 '15 at 06:39 PM

avatar image Slasmir Dec 03 '15 at 08:33 AM

Hello, that is not working. This just makes the shader unlit for both World and local calculations.

alt text alt text

If you see in the play view, the material is not casting or receiving shadows from other objects.

But this allows me to calculate the Local vertex shader part. Just as i where able to in my first post.

material.png (125.1 kB)
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avatar image AndrewHurley Dec 03 '15 at 05:32 PM

Perhaps using a 'Masked' or 'Translucent' blend mode, with the 'Default Lit' 'Shading Model', and combining that with a high opacity value.

This way you can still receive shadows from other objects, but control the amount of self shadowing through the Translucent Self Shadowing settings as well.

avatar image Slasmir Dec 08 '15 at 07:46 AM

Still not the thing.

Masked still calculate self shadowing even with a high opacity Mask, and Translucent is not casting nor reseaving shadows from/to other objects.

avatar image AndrewHurley Dec 15 '15 at 07:53 PM

Hey Slasmir,

Were you able to get your approach working?

I found that what you are trying to do, is primarily used with particle effects so they can control the self shadowing as well as shadows from other objects. There currently is a bug in place with Translucent Self Shadowing which we are investigating.

From what I understand, you will want a 'Default Lit' and 'Translucent' material for your set up.


Andrew Hurley

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