Material Attribute Opacity

Hi all, I’m trying to use a texture to drive Opacity in a Material Function and can’t seem to get it to work. The texture works on emissive and other channels(shown here in Normal) so it’s not the texture. The texture has a alpha channel to which I’ve tried with no success. Any tips?

- YouTube this is the effect I’m trying to make. I just need a gradient color to travel, while being masked out…shouldn’t be to hard…but it’s eluding me.

Hello walkinginspace,

From your description and your screenshot I was able to reproduce this issue on my end. It appears that the opacity channel never receives input from the texture sample. It also appears that when adding this function to a material it will the material will not allow the function to act as input.

After pooling more knowledge we have determined that this is a bug. I have entered a bug for this issue and it’s ticket number is UE-22344.

I will keep you up to date on this bugs progress.

Thanks . Would you have any other suggestions for achieving the effect from that youtube clip?

What you would need is a material where the emissive layer had a point of origin. Then perhaps add a panner. This of course would allow it to pan from one area and emanate outward in a direction. You may be able to then add a blueprint to call the event and have it tick once rather than a constant panning.

It will definitely take some research and trial and error. That’s the best guess I have off the top of my head.

Yea, sure will. It’s the masking of the area that is the problem. I need to be able to have a surface that then has a crawling/revealing texture grow over it…I’ll keep hacking away at it

Hi , any news on this?

Unfortunately, at this time, there are no updates for this issue. It is marked as “To-Do” and is currently unresolved.

Hi , just checking in to see if there was any progress with this…thanks!


I have looked into this bug report, and it is currently being investigated by our developers, but there is no timeline for a fix at this time.

Have a great day

Still doesn’t look like the bug has been fixed…nearly a year and a half and who knows how many builds…sigh…

Unreal Engine Issues and Bug Tracker (UE-22344) - it says resolved…guess I’ll look and see if it is:)

Any resolution?

I have the same issue. Opacity mask and opacity are not working inside of the material function build 4.16

Hey Malachi93,

If you’re still experiencing this issue in 4.17, do me a favor and open a new thread in the Bug Reports section. In the thread, please include a detailed list of repro steps that we can follow to reproduce the issue on our end, or a simplified test project so that we can get a ticket entered if necessary.


Opacity and opacity mask can’t preview in Material Function by Material Attributes,but in Material use the Material Attributes Opcity can work.I think its because when in Material Funcation you cant konw the Material Blend Mode,and the opacity and opacity mask cant preview.

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