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Get Opacity mask from material in C++?


Is there a way to get the opacity mask used by a material from C++? I'm rendering on UPanelCanvas and I need to hide all of the UImage objects that are underneath the zero opacity area.

circular opacity mask

So basically if I have a mask like the one illustrated above, everything within the white area shall be rendered and everything outside it, thus being in the black area shall not be rendered.

Am I missing something? Is there perhaps a better solution to it?

Thanks in advance.

P.S.: forum link

Product Version: UE 4.12
circularmask.png (143.1 kB)
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asked Oct 24 '16 at 04:29 PM in C++ Programming

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Hey Alisaxy-

The material class has an opacity mask variable that you can access publicly. If you have a material pointer, you can use this to get the opacity mask as necessary:

 UMaterial* MyMaterial;


Doug Wilson

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answered Oct 25 '16 at 01:47 PM

avatar image Alisaxy Oct 25 '16 at 05:26 PM

I've actually solved the problem without needing an opacity mask at all using UCanvasRenderTarget2D instead of UCanvasPanel. I imagine a need to mess around with FMaterialCompiler to get the data I need from the opacity mask and even then I wouldn't be able to partially hide the panel slots outside the mask as it's an all or nothing deal that way.

Nice to know still. :) Thanks!

avatar image Alisaxy Oct 25 '16 at 05:43 PM

Ah, found why I couldn't find it myself. :D I was confused by UMaterialInstanceDynamic & UMaterial, they're on different inheritance branches! I was always looking at the former, not the latter. Dang it! :) Well, the best experience is gained from making mistakes. Dully noted!

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