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Translucent Shadows and Vertex Color

I have a material that uses vertex color to switch between black and white to use in the opacity slot.

However, the transluscent shadows dont seem to take into account this. The shadows are the same no matter the vertex color (black or white) applied. My scene is fully static.


A1: Transluscent material with all white vertex color; A2: Transluscent material with all black vertex color; B: Near transparent Material; C: Opaque Material.

A1-S: Shadow of A1; A2-S: Shadow of A2; B-S: Shadow of B; C-S: Shadow of C.

You can see that the shadow of A1 and A2 are the same, even when the opacity is not.

Here's my material:


As you can see, I am using a Lerp to switch between my two opacities (and color).

Is this a bug or variable shadow transluscency is not working with vertex color?

Product Version: UE 4.15
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asked Apr 05 '17 at 05:46 PM in Bug Reports

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avatar image mngpssn Apr 05 '17 at 06:01 PM

If you have followed the tutorial for handling translucent shadows: TransShadow, be sure you already build the project.

Also, you can swith your lerp function with multiply function (as the tutorial) in order to know if the lerp function has to be modified.

avatar image Elggetto Apr 05 '17 at 07:49 PM

I did everything they told in this page. Still No luck.

I really think vertex painting and opacity dont go well together.

avatar image AndrewHurley Apr 26 '17 at 08:29 PM

Hey Elggetto,

I am going to run through a series of tests on my end to see what I can find. I'll return once I have completed my testing.


Andrew Hurley

avatar image Elggetto Apr 26 '17 at 11:40 PM

Okay thank you!

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So I was running some tests, and I am a bit thrown off by your own test case. What is it you expect to see, versus what you have presented?

Also, what happens if you switch your scene to be fully dynamic instead of static? i.e. Set your directional light to Movable.

I am seeing variable shadowed translucency when using a movable light, but not with static lighting which I believe is expected.


Andrew Hurley

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answered Apr 30 '17 at 09:48 PM

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