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[4.7.1] Deferred Decals not working from certain normals

Hi there!

I was just taking part of the March Unreal Game Jam and noticed that our bullet hole decals were only being applied to some surfaces based on their normal. After about an hour we had to abandon trying to fix this.

After the Jam, I downloaded the 4.7 Content Examples project and loaded the Decals level to hope and see what I was doing wrong, but to my surprise it appears that this might be an engine bug. alt text

Repro steps:

  1. Download 4.7 content examples

  2. Create project from content examples

  3. Launch Content Examples in 4.7.3.

  4. Load Decals level.

  5. Bring in a BSP cube and a Cube mesh near one of the decals.

  6. Copy or add a decal to the scene, apply a decal material and rotate and translate the decal near the new actors.

  7. Notice how it's not applying on certain surfaces anymore.

Product Version: Not Selected
decalsbroken.png (1.1 MB)
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asked Mar 23 '15 at 06:55 AM in Rendering

avatar image

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avatar image KamiUE Jul 16 '15 at 05:48 AM

i have same problem,decal shows on two side of a wall correctly ,and completely stretched on two other sides.i ve set those settings mentioned above but still the same result.any help??

avatar image AndrewHurley Jul 16 '15 at 02:14 PM

I am assuming you are seeing something like this?

Decal Actor Applied alt text

This is not a bug, but just how decals function. Think of a decal like a sticker in which you can only apply it to a single flat surface and does not wrap around objects.

Decal Arrow Direction alt text

The arrow connected to the sprite of the decal indicates forward facing direction in which the decal will be applied.

Let me know if this is the issue you are experiencing, or if it is something else. A screenshot of the issue would help me visualize your issue and determine the troubleshooting steps to take.

Thank you,

Andrew Hurley

avatar image tanyongdahaoren Oct 14 '16 at 07:58 AM

Thanks,but I don't want circled part,is there anyway?

avatar image tanyongdahaoren Oct 14 '16 at 08:11 AM

Another question,In decal material,"PixelNormalWS node" is not work correctly,Why? alt text

avatar image AndrewHurley Oct 14 '16 at 03:48 PM

Hey tanyongdahaoren,

Thanks for the bug report. I was able to confirm what you are reporting and have gone ahead and entered a bug report for the issue. You can track the issue following the link below on our public issues tracker.


Once the issue has been addressed by our engineers either myself or another staff member will return with an update.

Let me know if you have further questions or need additional assistance.


Andrew Hurley

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1 answer: sort voted first

Hello GD09Scott,

What you are reporting is actually not a bug, and is working as intended. In order to get your decals to display properly you will need to edit a few settings. Firstly, the reason it is not showing on that particular face is because it is not receiving direct light as a 'Translucent' decal. By translucent I mean the 'Decal Blend Mode' is set to 'Translucent.' Use the directions and images to get your decals to render correctly.

Project Settings

alt text

Go into your 'Project Settings' and within the 'Rendering' section scroll down to the 'Lighting' and 'Optimizations' options and check 'Dbuffer Decals', 'Movables in early Z-pass', and 'Early Z-pass' to 'Opaque and Masked Meshes.'

Decal Material Properties

alt text

After making these changes, close and restart the editor. Rebuild your scene and you should now be able to see the decal on the face of the BSP.

Let me know if you are still having difficulties, or if you have further questions.


Andrew Hurley

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answered Mar 23 '15 at 03:26 PM

avatar image LordMorin Mar 23 '15 at 09:01 PM

Thanks Hurley, looking forward to testing this out when I get home!

avatar image CharlyCarrelet Jun 24 '15 at 04:02 PM

Thanks a lot, it works fine !

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